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FAQ: Glossary of Terms

Discussion in 'HDR-FOX T2 Freeview Recorder' started by Black Hole, Jul 29, 2011.

  1. Black Hole

    Black Hole Felonius Gru

    OK, same deal - anybody with something to add, post it up and I'll add it in.

    Encyclopedic Glossary of Terms

    Readers please note: while much of the following is general information, where relevant it is specific to the Humax HDR-FOX T2 and (to a lesser extent) the HD-FOX T2.

    BYTs
    Bright Young Things - Fittingly at the top of the list (even though I've thought of something to explain starting with "A"), BYTs is the term I've coined for the fantastic bunch with the youth and energy to figure out the hacks that comprise the CF (see CF) for the HD/HDR-FOX T2. Wind the clock back 20 or 30 years and it could have been me, but the brain now struggles to keep up. Don't worry, the rest of this glossary is serious (but not necessarily without tongue-in-cheek)!​

    Credit where credit is due: af123 is the driving force behind the creation of a customised firmware update (which provides the way in), and much of the code that subsequently gets installed to the hard drive as packages. raydon started the ball rolling by coming up with the Foxy process in the first place. Other contributors I count as BYTs are xyz321, Drutt, Tawny, Sam Widges, Ian Jukes, ChrisDaniels, philhdr, njm (anyone feeling left out: not intentional, ping me a PM and I'll add you in). A more extensive list of credits and attributions can be found HERE (click).​

    I don't count myself as a BYT, I follow in their footsteps as groupie and self-appointed archivist.​

    AD
    Audio Description - A service which provides commentary describing the inaudible aspects of a TV programme for the blind/partially sighted. Some users have been perplexed to find this turned on apparently randomly: there is a setting for it in the menus, and also the speaker button on the handset (to the right of "OPT+") cycles through the various modes - which might have been pressed accidentally.​

    AR
    Accurate Recording - See EPG.​

    Booting
    Booting is the jargon for the process of electronics hardware sorting itself out after it has been turned on, prior to being able to do something useful. The term comes from the phrase "pulled up by his own boot straps" - meaning making something of yourself from nothing - and was originally referred to as boot-strapping and then abbreviated to booting. Computer hardware doesn't know what to do until it has a program loaded into memory, so dedicated mechanisms are required to get the first (simple) program into memory which can then take over and load a more complex program... and so on. Dedicated hardware (which commonly has its program readily available and doesn't need loading) often needs to set up operating parameters under program instruction, and this is also considered part of the boot process. See also Firmware v. Software.​

    With regard to the Humax HD- or HDR-FOX T2, there are various ways they can be booted, with varying effects and consequences. To aid clear communication I encourage the use of standardised terms to describe them, as follows:​

    Cold Start / Cold Restart - We use "cold" to describe a state where no power is arriving at the unit at all. Thus a cold start is when the unit is booted by turning the power on. In the case of the HDR-FOX T2, there is a mains switch on the back. In the case of the HD-FOX T2, there is no switch so a cold start is when the unit is plugged in at the wall and the wall switch (if there is one) turned on. A cold restart is when the unit was powered, but power is removed and then restored.​

    Warm Start / Warm Restart - Converse to "cold", "warm" describes a state where the unit was powered but in stand-by, so a warm start is when the unit was turned on using the stand-by button or the remote control. I have noticed there is sometimes a difference between a button warm start and a remote control warm start (on the HD-FOX T2). A warm restart is when the unit is put into stand-by and then turned on again, but note that a proper warm restart does not happen unless some time is allowed between the off and the on for the shut-down processes to complete (approx 30 secs).​

    Hard Reset - The HD-FOX T2 is blessed with a reset button (located behind the front flap). Pressing this (while the unit is powered) performs a hard reset.​

    Soft Reset - Also known as a software reset, this is where software executes a restart command (as can be done from the custom firmware Web Interface when required after a remote recording schedule change). Same effect as a warm restart.​

    CF, CFW
    Custom (or Customised) Firmware. In very brief summary: a few small additions to the standard firmware in the Humax allow additional program code to be installed on the hard drive and executed as part of the day-to-day operational environment, creating a rich set of additional facilities (for example: web browser access to the files and EPG; ability to download StDef and HiDef recordings in the clear; external drives in NTFS format... etc). The additions to the standard firmware are applied by installing a customised firmware update file from a USB drive or stick, and removing them again is as simple as re-updating with the original Humax firmware. With the firmware additions in place, a minimal web interface becomes available and the full suite of software additions can be downloaded and installed from there, and after that the user can choose to install a selection of optional "packages". Thus the "CF" is actually mostly software rather than firmware. See Firmware v Software.

    Note that another common meaning of CF is "Compact Flash" (a type of memory card, particularly used in cameras), but this is unlikely to cause confusion in the context of the HDR-FOX T2.​

    Channel
    See LCN.​

    CMYK
    See Colour Space.​

    Colour Space
    There is a wide variety of methods for specifying the colour and brightness of a pixel, and which is best depends on the specific application. In the case of displays which generate their own light (rather than reflect light like a painting), the emitters which contribute to the appearance of each pixel are red, green, and blue - hence RGB. Typically each "colour channel" is given a brightness value between 0 and 255 (ie one byte of data), three bytes providing the data for one pixel where "0,0,0" represents black, and "255,255,255" represents white (the same amount of each of red, green, and blue produces neutral grey tones). The higher the colour channel values, the brighter the pixel will be.

    This is in contrast to printing on paper, where instead of being "additive", the inks are "subtractive". Light falling on the page is reflected by the white paper, and the pigments in the ink absorb some of the spectrum. The inks used for full-colour printing are CMYK: cyan, magenta, yellow, and "K" for black (not "B" which could be confused with blue) - black is used in addition to CMY because it would take an awful lot of CMY pigments to make a dot properly black. Cyan, magenta, and yellow are the "complimentary" colours to red, green, and blue. In this case, the higher the colour channel values, the darker the pixel will be.

    Before the digital era, video signals were sent as analogue waveforms which represented each row (then called a "line"). Methods were invented to encode the colour and brightness in the video signal which suited each particular transmission medium, hence we have Composite and Component video. Component video is an extension to monochrome video - where a single channel carries a luminance signal (ie just the brightnesses along a black&white line in the raster). Two "side" channels are added which carry colour difference signals, and combined with the luminance are used to calculate the RGB signals. The advantage (at the time) was that the luminance signal could still be used on its own by ignoring the colour difference signals. Component signals are variously called YCbCr, Y'CbCr, YPbPr, YUV ("Y" representing luminance) - the differences being in the precise way that the components are calculated from RGB or vice versa.

    Composite takes the component signals and combines them into a single analogue waveform by modulating the colour diffence signals onto a high-frequency carrier wave. The cleverness of this is that a monochrome receiver will not have been designed to detect the colour carrier, so will only see the luminance component. The manner in which the colour difference signals are modulated is the difference between the European PAL (Phase Alternating Line) system and the American NTSC (National Television System Committee) system (PAL was designed to correct the problems that NTSC had when using wireless broadcast transmission - it became known as "Never Twice the Same Colour").

    No colour system can represent every possible hue, intensity, and brightness. Apart from the granularity of the digital representation (eg 24-bit RGB has "only" 16 million different values), there are colours which cannot be reproduced just by adding elements of red, green, and blue light (in the case of RGB). The method of encoding the colour information is called the "colour space", and the range of colours that can be represented within it is the "gamut". In fact, the colour spaces in use are designed to be a close match to the human visual system - so although in theory not every colour can be reproduced, it is of little practical disadvantage (unless you are experimenting with colour perception in animals - including humans).

    The signal connections for analogue video depend on which colour system is in use. RGB requires three channels (typically a triple screened cable with RCA/phono connectors). Add stereo audio to that and there are five channels. Component similarly, three video and two audio. Composite plus stereo audio is the typical three-wire connection, with the video signal on the yellow connector and the stereo audio on red and white. SCART includes connections for composite and stereo audio, plus three channels that can be used as RGB or component according to the equipment (sometimes there is a selectable option in a settings menu - if given the choice use RGB).​

    CRID, P-CRID, S-CRID
    Content Reference IDentifier - The EPG provides unique reference codes to the programmes which are useful for machines to track the programmes (and potentially to retrieve additional information via the Internet). The Programme CRID (P-CRID - unofficial) identifies the programme individually and allows the Humax to ensure that repeats don't get recorded, the Series CRID (S-CRID - unofficial) allows it to identify programmes to be recorded by series link. The CRID codes can be seen on the Humax programme information screen (via the "i" button) by turning them on in the hidden service menu.

    (The use of abbreviations PRID and SRID is now deprecated.)​

    CRT
    Cathode-Ray Tube - the part which displays the picture in the old-fashioned bulky TVs, ie not plasma, LCD, or LED (or any other flat-panel technology).​

    DHCP
    Dynamic Host Configuration Protocol - For your devices to co-exist on your home network, they each need a unique "address" so that data meant for a particular device gets there and not somewhere else. This is the IP (Internet Protocol) Address, and typically for a home network the addresses will be 192.168.0.x or 192.168.1.x (where x is 0-255). It is possible to allocate these addresses manually, but it is a chore and you have to make sure you choose a valid address and don't allocate the same address to more than one device. DHCP is an automatic system which lets the device request an address from a manager device - often the router in your broadband connection - but it is dynamic which can result in problems with the allocated IP address changing (particularly if the router reboots). If you need to be sure what IP address is allocated to the Humax, use DHCP initially and then fix it by changing to manual in the settings (but this can lead to its own problems), or configure the router to always hand out the same address by DHCP, or do both: fix the address at the router (which prevents it being handed to any other device) and set the Humax manually (which avoids problems with HomePlugs being slow to wake up).​

    DLNA
    Digital Living Network Alliance - a set of standards which allow compatible devices to locate each other on the local Ethernet network, and access each other's content for streamed playback, without the user having to understand network configuration settings. If you want to use the Humax's media streaming capability to show its content elsewhere (firmware update 1.02.20 onwards), you will need a DLNA client - possibly a program running on a PC, or another Humax box - although it is possible to use non-DLNA media players if you can work out the correct network reference. The advantage of using another Humax is that it can access the HiDef content too (most other solutions will only access StDef recordings - see DTCP). You can also use a DLNA server to provide content to the Humax, again either running on a PC or using a NAS box with built-in DLNA capability (many do these days). See also UPnP.​

    Dolby
    Dolby Laboratories invented and patented a number of processes for deriving multichannel audio (surround sound) over the years. The original Dolby encoder used the relative phasing of signals in the stereo channels (essentially a difference signal) to create a rear channel - this only works properly if the left and right stereo channels are recorded deliberately with this in mind, and the technique for achieving this is the essence of the Dolby patents. Dolby Pro Logic is an updated surround-from-stereo decoder. Cinema film used Dolby sound tracks, but then added more sound tracks (particularly 70mm film) to achieve full multi-track surround sound without Dolby encoding (and licence fees). Dolby Labs then patented a way to re-organise the multiple sound tracks to use them more effectively, and so the arms race went on. Now we have digital audio streams with enough bandwidth to carry a full high-quality stereo signal in a lossless format or surround in an encoded format, Dolby TrueHD is a codec for transmitting up to 14-channel surround sound in a (reportedly) lossless format. See also Surround Sound. Founder Ray Dolby, who started out by developing filters to reduce the background hiss in recordings (and hence improve the perceived quality dramatically), died in September 2013 aged 80.​

    DRM
    Digital Rights Management - the means by which copyright holders attempt to protect their material by limiting its use, in particular securing it by means of encryption or other measures so that (for example) it can't be copied or it is only playable on a particular licenced device. The encryption of the recordings on the HD/HDR-FOX is a form of DRM, see also DTCP.​

    DSO
    Digital Switch-Over - The process of the UK converting from fully-analogue TV to fully-digital. The first main phase introduced digital transmissions alongside the analogue, region by region, but the digital channels have/had to be at reduced power to avoid interference. The second main phase involves turning off the analogue transmissions completely and boosting the digital power to achieve the required geographic coverage. There are various sub-phases where the transmission frequencies are juggled around. The London area will be almost the last to complete, the mandarins having decided to experiment on the rest of us first.​

    DTCP
    Digital Transmission Content Protection - a means of securing rights-restricted material transferred by any digital channel (in our case Ethernet). As a media server, the Humax protects HiDef recordings by DTCP, thus restricting your choice of clients to those which have paid the relevant licence fees (not unlike HDCP). Note that (by running the CF) DTCP can be effectively switched off. See also HDCP.​

    DTT
    Digital Terrestrial Television - See DVB.​

    DVB
    Digital Video Broadcasting - This is the replacement for the analogue method of TV transmission, the advantage being that a digital data stream occupying the same bandwidth in the frequency spectrum as one analogue service (and using modern data-compression techniques) can carry sufficient information for 4 HiDef video services or many StDef video plus music and text services. "DVB" encompasses DVB-T/DVB-S (terrestrial and satellite) and DVB-T2/DVB-S2 (second generation terrestrial and satellite) and many other standards. In particular: DVB-T2 uses an improved (more efficient) video compression technique that is used in the UK for HiDef TV services, while the StDef services are transmitted using DVB-T (if you are buying a TV tuner card or dongle for your PC and you want it to receive HiDef, make sure it is T2 capable). See also LCN.​

    Encryption
    Both HDR- and HD-FOX encrypt their recordings using keys unique to each individual machine and are undecypherable on any other machine. We have suspicions about the encryption method, but the keys are buried inside the hardware and unobtainable. As standard, the HDR-FOX decrypts StDef recordings when played to TV (obviously), copied to a USB drive, or streamed to a DLNA client. HiDef is not decrypted when copied, and is sent as a protected stream to DLNA. The HD-FOX only decrypts when playing back to TV.

    The CF was born out of the desire to eliminate these restrictions (but has since become much more). First we were gifted Foxy, which can be used to unlock HiDef recordings for decryption when copied to USB. Now we can unlock HiDef automatically in the background so that it can also be streamed unprotected, and then by a bit of trickery stream StDef or HiDef to a file capture on the same device, and thus replace an encrypted recording with a decrypted one - all without user intervention.

    Things are not so rosy for the HD-FOX, which lacks the DLNA server functionality used for auto-decryption on the HDR-FOX. However, by forcing it to run HDR code it is possible to decrypt StDef or HiDef using a virtual drive and the handset copy functions.

    See also .ts, Foxy.​

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  2. Black Hole

    Black Hole Felonius Gru

    EPG
    Electronic Programme Guide - Along with the broadcast stations on Freeview comes a data channel containing information about the upcoming programmes (on all channels) for the next 8 days. This information is collected and organised for display when you press the "Guide" button. The content is broadcast continuously cyclically, with the more important information (programmes on the current channel; programmes on all channels today) repeated more often than less important (programmes other channels and later in the future) so that the whole download is complete in about 15 minutes. In addition to the programme guide is a status channel for the Now/Next display and programme change-over, so that (in theory) PVRs can start a recording automatically at the start of a programme, even if it has been delayed (or brought forward). This is known as AR (Accurate Recording), but doesn't always work because broadcasters are not reliable in transmitting this information (some worse than others). See also CRID.​

    Ext3
    This is a method for arranging data on a hard drive, used by Linux systems (including the Humax). Unlike FAT32, it can accommodate huge video files without being truncated. Unlike NTFS, the Humax can write to it (although the custom firmware developments have made NTFS writable). Unfortunately, Windows PCs can't access Ext3 without help in the form of a special driver. The Humax can format a drive up to 1TByte to Ext3 through its menus (which will wipe anything that's on the drive), but beware that the Humax format has compatibility issues with other Linux systems (and also possibly the Windows driver). If you are adding an external drive to the Humax that will be dedicated to the purpose - no problem (and you must format this way if you want to make recordings directly to the external drive), but if you might want to connect the drive to other systems and access the contents it would be as well to format it elsewhere. See also FAT32 and NTFS.​

    Note that the CF needs to be installed on an Ext3 drive (or at least an Ext2 drive - the forerunner of Ext3 and easier to accommodate on a UPD).​

    FAQ
    Frequently Asked Questions - the popular Internet abbreviation for the section of a web site that contains information which the authors are fed up with answering individually, or expect to be asked so they put it up as a pre-emptive measure. FAQ has since been adopted to mean any unchanging reference material. In a similar vein is RFC (Request For Clarification), which has become a banner for information bulletins and software standards even when there has been no request involved!​

    FAT / FAT32
    File Allocation Table - This is a method for arranging data on a hard drive, the other main one from the PC point of view being NTFS. The original FAT was only suitable for small drives, but in those days drives were only small. FAT32 drives can be much bigger (2TByte), but something to be very aware of when playing with video is the file size limit: each individual file on a FAT32 drive can be no greater than 4GBytes in size (that's a couple of hours of StDef, but less than an hour of HiDef). A Windows PC can access a FAT32 drive no problem, so can Linux and the Humax - but if the Humax tries to write a file that is larger than 4GBytes to a FAT32 drive, the file will be truncated and the Humax won't tell you there has been an error. See also NTFS and Ext3.​

    Firmware v. Software
    Hardware is the nuts and bolts and electronic components which physically make up the product. Software is what the software engineers (programmers) write to load and run on the hardware to make it do something useful, "soft" in that it evaporates if you turn the power off.

    That was the old days, when the first thing you had to do with a computer is feed in a loader program by hand using switches and lights to enter it into the program memory, so that it could then fetch the actual program in from punched paper tape. As technology developed, it became possible to store small amounts of program code in a way that did not disappear when the power went off, so the loader program became "fixed" and in the realms of the hardware engineers, and acquired the term "firmware" (being somewhere between hard and soft). Many aspects of complex modern electronics now have some elements of their operation defined by program code, embedded within their manufacture and untouchable by the end user (even the exact function of a logic chip). Because they are unchanging in the finished product (except sometimes in an update process), these too are regarded as firmware - whether written by a hardware team or software engineers.

    We are very lax when discussing the Humax when referring to software or firmware (even me). The operating system (which, on a PC, would be loaded from hard disk during boot-up and therefore definitely software) is stored in non-volatile memory and available as soon as the unit is switched on. It is therefore firmware, and the OTA or USB updates are firmware updates. The recordings on the internal or external drives are software (although not created by an intellectual design process), or more reasonably just data. The Modified Software Project is mostly downloaded to hard disk (avoiding space constraints in the non-volatile memory), so that aspect is software, but it must add hooks into the existing firmware in order to run, so there is a slight firmware addition but then it is software after that. In short, I think we are justified in referring to the standard Humax code as firmware, and the MSP as software (but see MSP).​

    Foxy
    Recordings made by the Humax are encrypted on the drive using a code unique to each individual box. Directly accessing the recording files (eg by FTP) sees only the encrypted files, so any files extracted are only any use for backup purposes and must be returned to that specific Humax to be decrypted for replay. Copying an StDef recording to USB using the Humax menus decrypts the file, but not so HiDef recordings - which remain encrypted to oblige the broadcasters. Foxy is a utility that runs on a Windows PC and is capable of clearing the Enc flag on a HiDef recording, and thus make it decryptable just like a StDef recording. See also .ts. Users of the modified software can clear the Enc flag automatically within the Humax, no need for Foxy.​

    FTP / FXP
    File Transfer Protocol - a simple (for computers) standard for two devices to communicate across a network for copying files about. Both ends have to understand FTP (and have it turned on) for it to work though! With FTP turned on in the menu settings, it is possible to access the Humax by FTP. Typically one runs an FTP client on a PC which then provides drag-and-drop file management (just like using Windows Explorer). File eXchange Protocol is similar, but allows for data to be moved between two remote devices without having to pass through the command console (so it only gets moved once, not twice).​

    Gamut
    See Colour Space.​

    GiB
    See KiB

    HD / HDD
    Hard (Disk) Drive (for completeness) - computer disk* drive, either bare for inclusion in a piece of equipment or housed in a case for connection by USB (external/portable hard drive).​

    Disambiguation: When referring to a hard drive, I recommend using the abbreviation 'HDD' to avoid confusion.​

    * In case any "traditional spellers" quibble at 'disk':- like 'program', 'disk' is an accepted spelling in computer terminology and has its roots in the abbreviation for 'diskette'. In normal English 'disc' remains correct for describing a flat circular object, and 'programme' is a planned series of events.​

    HD / HiDef
    High Definition - I use HiDef to disambiguate from other meanings of HD: eg Hard Drive, or HD-FOX T2. By HiDef we mean the content recorded from the "Freeview HD" channels eg BBC HD, BBC1 HD etc. See also StDef.​

    Disambiguation: When referring to High Definition, I recommend using the abbreviation 'HiDef' to avoid confusion.​

    HD Ready
    The HiDef TV services are transmitted by a method which is not compatible with early (or budget) TV tuners, and a TV with a screen able to display at least 1280x720 pixels but only a StDef tuner is described in the marketing blurb as HD Ready - ie it can display a HiDef picture if fed from and external source by HDMI (eg a blu-ray player), but it is not able to receive and decode HiDef broadcasts itself. See DVB.​

    HDCP
    High bandwidth Digital Content Protection - How do the big film companies publish HiDef Blu-ray video discs and stop them being instantly pirated? Well, there's not much chance of stopping determined pirates, but they can stop the ordinary public from making a copy to pass around the family (or a legitimate safety backup) by making sure the content never appears accessibly in the clear (code-speak for unencrypted). HDCP is enforced by licence - equipment makers have to sign up to it to be granted access to the technology, pay a lot for it, and they undertake not to let the datastream out. What it does is to negotiate the HDMI link. If the source is providing copy-protected material, it first negotiates with the destination that it requires a secure link (and only an HDCP-compliant device knows how to negotiate), the link is established, and then the video is sent until the link gets broken (and has to be re-negotiated). What is true of Blu-ray is also true of FreeviewHD - the broadcasters wish to keep control of it - so the Humax also negotiates a secure link with the TV. See also HDMI.​

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    Last edited: Sep 1, 2015
  3. Black Hole

    Black Hole Felonius Gru

    HD-FOX T2
    The version of the Humax FreeviewHD tuner/PVR which does not include an internal hard drive and therefore only records to an external drive. "HD" for FreeviewHD, "T2" is the modulation scheme for broadcast digital HD used in the UK (not in common with most of the rest of the world). The HD-FOX T2 is also one tuner short of a full set (deficient in the tuner division to the leg of one - click). The HD-FOX T2 is however useful as a fully-featured DLNA client for a HDR-FOX T2 on the same network, able to stream StDef and HiDef recordings from scratch.

    Limitations of the HD-FOX T2 (compared with HDR-FOX T2):
    • No internal hard drive, record to external Humax-formatted drive only;
    • Only one USB port (at the rear, under the Ethernet port);
    • No mains on/off switch;
    • One tuner, no simultaneous recording/viewing of two channels;
    • No facility to decrypt recordings except by playback to HDMI TV output (note 2);
    • No DLNA (streaming) media server (note 1);
    • No FTP server (note 1).
    Unlike the HDR-FOX T2, the HD-FOX T2 boasts a reset button!

    HD-FOX T2 owners wishing to install the CF should note the following: Because the HD-FOX T2 does not have an internal HDD and internal Flash storage is at a premium, an external HDD or UPD is required to load the CF. However, the CF assumes file system facilities that are available to the HDR-FOX T2 from its internal Ext3 HDD, the consequence being that using a FAT32 HDD or UPD will result in incompatibilities. Mostly, people using the HD-FOX T2 as their only device will have an Ext3 HDD connected for making recordings, so that is no problem. Otherwise, there is a work-around to format a UPD as Ext2 (Ext3 is not happy on a UPD).

    Further details HERE (click - HD-FOX forum) or HERE (click - MSP forum).​

    Note 1: These functions can be added by installing the CF (but are of little use without decrypted recordings).
    Note 2: Decryption can be achieved by temporarily running code from the HDR-FOX T2. There is an "HDR Mode" package in the CF for this.​

    HDMI
    High Definition Multimedia Interface - Unless you have a steam telly and are using the SCART interface, HDMI will be the type of connection you are using to send the video/sound to your TV (at the time of writing I still had a couple of tellies that didn't even have SCART). In essence: SCART is an analogue interface, in other words the picture information is sent as continuous voltage levels; whereas HDMI is a digital interface and every single pixel on the screen is defined precisely by (typically) three bytes of data, 25 times a second. Add it up - that's a lot of data! SCART is okay for traditional 625-line pre-digital TV, but the analogue waveforms cannot keep up with the detail in HiDef video. The digital data in HDMI means that at each binary bit of every pixel, the transmission scheme only has to successfully communicate the difference between a "1" and a "0" - and even that is tricky at up to 340 million bits per second over a few metres of cheap cable. See also SCART, HDCP.​

    Footnote regarding the HDMI cable rip-off: All too often (it has been reported) the TV showrooms try to sell you a "high quality" HDMI cable for anything up to £50 or more. This is utter rubbish and a £5 cable will do just as well (or even one from Poundland costing - guess how much)... as long as it only has to be 6 feet long (1.8m). The problem starts when/if you want to send the signal further than that, and then quality really does matter.

    The maximum design length of cable is 10m, for which you need a high quality cable, but still need not be too expensive: I have a 10m cable which works perfectly, sourced from Amazon for less than a tenner in 2013 - compare that with the price of a short "audiophile quality" cable. I'll give the fanatics a clue: HDMI is digital, so there cannot be any nuances in the quality of video or sound induced by the transmission medium whatsoever - it either works or it doesn't (I would love to run a blind test on an audiophile who claims the cable makes a difference). 15m cables are also available, and may work, but buyer beware: the 10m design limit means the HDMI spec has an allowance for the timing delays and voltage drops incurred over 10m of cable maximum, and anything beyond that is pushing your luck rather than certainty (although you may well get away with it, like overclocking a PC processor).​

    HDR
    High Dynamic Range - This is a new standard for TV which, instead of (or as well as) increasing the display resolution beyond 1920x1080 pixels ("2K") to "4K" (3480x2160) or even "8K" (7680x4320), increases the number of bits used to define the colour and brightness of each pixel. Prior to this, practically all consumer digital imaging (cameras, scanners, printers, monitors, TVs) used 8 bits (one byte) to represent each of the three primary colours red, green, and blue (ie 24 bits per pixel), representing white as the maximum value in each colour channel (255,255,255) and black as the minimum value (0,0,0). HDR requires at least 10 bits per channel, so that instead of having "only" 256 graduations of tone in each of red, green, and blue, there are 1024 graduations (or more - 4096 with 12 bits per channel).

    The 24-bit standard works fine for "busy" images, but when an image contains a large area of a single colour, and that colour has subtle variations, one can sometimes see a "steppiness" in the reproduction - particularly noticeable on areas of sky or close-ups of skin tone. The reason is that the human eye has a greater sensitivity to variations in colour than can be represented by changing the least significant bit in one colour channel in the 24-bit system, but this is normally masked by gross changes in colour in adjacent areas or by rapidly changing images. Using a 30-bit system makes the individual steps one quarter the difference, and a 36-bit system is a quarter of that again, practically eliminating the difference between the sensitivity of the eye and the capability of the system.

    Increasing the number of bits also permits the brightness of "white" and the darkness of "black" to be increased (contrast). The black displayed by a TV is never completely black, and naturally the brightest white is limited by the amount of light the screen can produce, but even so if the difference between black and white is made too great the size of the steps represented by one bit is also increased (there only being 255 steps between fully off and fully on, in the 24-bit system). With 30 or 36 bits it becomes practical to expand the contrast without impacting the colour resolution, and this is where the "High Dynamic Range" name comes from. HDR photography keeps detail in over-exposed or under-exposed areas of a picture where conventional 24-bit imaging would just clip it (and no amount of image processing can reclaim it). HDR is thought to be a better enhancement to general viewing than UHD.

    Of course, it's no good having an HDR TV unless there is content to view on it. There are various proposed upgrades to the TV transmission system which may eventually result in an HDR TV service, and it is anyone's guess whether TVs purchased now will be compatible with whatever system eventually enters service. Meanwhile you can expect Internet TV services (such as Netflix) to stream HDR content, and content to be playable from Blu-Ray etc.

    See also UHD.

    Note: in the context of posts on this forum, "HDR" is more likely to refer to "HDR-FOX", or occasionally "Foxsat-HDR". See HDR-FOX T2.​

    HDR-FOX T2
    The version of the Humax FreeviewHD tuner/PVR which does include an internal hard drive. "HDR" for FreeviewHD Recorder, "T2" is the modulation scheme for broadcast digital HD used in the UK (not in common with most of the rest of the world). See also HD-FOX T2. The "R" in "HDR-FOX" is presumably supposed to stand for "recorder", but the HD-FOX is also capable of recording - just not without providing an external HDD.​

    Humax / Hummy
    Abbreviated / jocular reference to a box made by Humax (the company). In the HDR-FOX T2 section of the Hummy.tv forum it would be natural to presume the author is referring to the HDR-FOX T2 unless otherwise stated. Much of the discussion also applies to the HD-FOX T2, as indeed most of the discussion in the HD-FOX T2 section also applies to the HDR-FOX T2 (I imagine).​

    .hdf
    Humax Download Format - Firmware updates for the Humax are distributed as .hdf files. If a USB memory stick is plugged into the Humax at boot-up, and it contains a .hdf file (precisely named "hdr_fox_t2_upgrade.hdf" in the case of the HDR-FOX T2) in the top directory, the Humax will start a firmware update from the file (even if that version or a more recent version of firmware is already installed). The firmware component of the CF is also distributed as .hdf files. Updating by downloading a .hdf to a USB stick is an alternative to the OTA (Over The Air) update service that happens automatically in areas able to receive FreeviewHD.​

    HomePlug
    This is a method for extending a wired Ethernet network over the domestic mains wiring. It requires two or more compatible units (called HomePlugs) plugged into the mains sockets, and these units then create a network between each other through the mains - which the user can then connect to through the Ethernet sockets on each. This means proper wired Ethernet connections to network devices, without trailing wires around the house and as an alternative to WiFi. Normally one would install the first HomePlug connected to your router, and then subsequent HomePlugs will link to that.

    HomePlugs come in different speed capabilities (85, 200, 500 Mbps), but note that (rather like WIFi) this is a theoretical maximum rather than a guaranteed data rate. 200 and 500 Mbps units can be mix-and-matched on the same network, but the network will operate at the speed of the slowest device.

    HomePlugs from different manufacturers are supposed to be compatible with each other (but note that 85Mbps units are incompatible with 200/500Mbps units), but if for any reason they don't happen to work it can be nigh on impossible to work out which unit is to blame - so in my opinion it is best to stick with one brand and then there is no doubt who is at fault.

    Beyond the bog-standard "plug into a mains socket and get an Ethernet port" functionality, HomePlugs are available which:
    • Provide a pass-through for the mains socket, so the HomePlug doesn't eliminate a socket unnecessarily;
    • Provide multiple Ethernet sockets, eliminating an Ethernet switch if you need more than one connection in that location;
    • Provide a WiFi node so that the HomePlug network can be used to extend the coverage of your WiFi network.
    While 200Mbps is adequate for HiDef streaming, I recommend installing the best you can afford - it is a one-off purchase.​

    IP Address
    Internet Protocol Address - See DHCP.​

    KiB, MiB, GiB
    The traditional units for counting bytes of storage can result in confusion. It has long been a convention that the prefix "k" (kilo) denotes "multiply by 1000", and "K" denotes a multiplier of 1024 (2 to the power 10). However, the same trick does not work with the scientific multipliers for 1,000,000 ("M", mega) or 1,000,000,000 ("G", giga). In computerese we would normally regard "1 MB" (for example) as meaning 1,048,576 bytes (2 to the power 20), but disk drive manufacturers (etc) have been known to take advantage of the ambiguity and advertise a 93GB drive as 100GB (using the decimal version of "G") - this is frequently the cause of consternation when users run a disk check and find there is unaccounted "missing" capacity.​

    The solution is an unambiguous separation of decimal and binary prefixes. Kilo-binary becomes "kibi", prefix "Ki"; Mega-binary is "mebi", prefix "Mi"; etc. For reference:

    Ki - kibi - 1,024 (2^10)
    Mi - mebi - 1,048,576 (1,024Ki, 2^20)
    Gi - gibi - 1,073,741,824 (1,024Mi, 2^30)
    Ti - tebi - 1,099,511,627,776 (1,024Gi, 2^40)
    Pi - pebi - 1,125,899,906,842,624 (1,024Ti, 2^50)
    Ei - exbi - 1,152,921,504,606,846,976 (1,024Pi, 2^60)
    Zi - zebi - 1,180,591,620,717,411,303,424 (1,024Ei, 2^70)
    Yi - yobi - 1,208,925,819,614,629,174,706,176 (1,024Zi, 2^80)

    Incidentally, while I'm on the subject, "b" stands for "bit" and "B" stands for "byte" (a block of 8 bits).​

    LCN
    Logical Channel Number - These are the "channel numbers" that you find allocated to the services on your digital TV / set-top box (including the Humax) - for example: "1" gets you BBC1, "9" is BBC FOUR, "12" is Dave and so on.​

    In the days of UHF analogue TV, UK TV transmission frequencies were given channel numbers from 21 to 69 (each 8MHz apart starting from channel 21 = 471.25MHz), and the broadcast stations (from any one transmitter) had a whole channel each. To get universal coverage across the UK requires lots of transmitters, and because neighbouring transmitters would interfere with each other if they were on the same frequency (even if transmitting the same station on that frequency) different channels have to be allocated to the same station from different transmitters, so ultimately five TV stations were the most that could be fitted into the UK coverage (BBC1, BBC2, ITV, Channel 4, Five).​

    DVB (Digital Video Broadcasting) replaces the analogue one-station-per-broadcast-channel with a digital data stream on each broadcast channel, and similar conditions apply to interference from adjacent transmitters but now there are up to six "multiplexes" from each transmitter, broadcast on similar channel number allocations as before. However, inside each multiplex (or "mux") the data stream has sufficient capacity for about 10 StDef TV stations (more if they time-share) plus many audio-only and text services, or 4 HiDef TV stations.​

    This is where the LCN come in. Each service across all the multiplexes is allocated a unique LCN, and this is the position on the digital TV's "tuning dial" where the service will be found - regardless of what region you are in. The LCN information is embedded in the data stream, so when the TV or set-top box tunes itself in BBC1 is always on 1, Dave on 12, and so on.​

    Disambiguation: To avoid confusion, I recommend the following usages: 'Channel' should refer to the frequency used for the transmission; 'Station' or 'Service' should refer to an individual TV, radio, or text feed within the digital multiplex ('service' is the industry standard); and 'LCN' is the number you have to dial in to the TV/STB to receive a particular service.​

    LNB
    Low Noise Block - A piece of electronics fitted at the focus (or via a waveguide to the focus) of a satellite dish. It avoids the impracticality of carrying the satellite microwave signal to the receiver in the house by down-converting - that is it converts the microwave frequency signal into a UHF signal which can be transmitted along a standard co-axial cable. Power for the LNB is sent up the same cable from the receiver, as are various control signals such as frequency band and horizontal or vertical polarisation selection. This implies the dish doesn't only have to point at the satellite, it also has to be orientated correctly relative to the satellite's idea of "up", and the use of control signals means you can't split a satellite down-feed cable between multiple receivers (like you might a terrestrial TV feed) without taking special measures (such as a receiver specifically designed to provide signal daisy-chaining).

    Some LNB assemblies have multiple individual LNBs providing separate outputs for two or more co-ax connections to feed two or more receivers. Using a quad LNB with four downlinks feeding a special distribution amplifier module, it is possible to provide complete coverage of the satellite TV band to as many receivers as can be connected to the ports on the distribution amp (this is how communal satellite TV systems work).​

    Why is it called a "Low Noise Block"? 'Low Noise' refers to its electronic properties - the microwave satellite signal is extremely weak when received at the dish and its amplification before sending it down the co-ax to the receiver must not introduce additional electronic 'noise' that would swamp the signal - also known as 'static'. 'Block' is actually abbreviated from 'block down-converter', meaning an entire frequency band (block) is shifted rather than an individual tuned frequency, so the full description is "low-noise wide-band down-converter".​

    LPCM
    See PCM

    MAC

    Media Access Control - This refers to the "physical layer" of the Ethernet protocol, which is how the hardware intercommunicates and moves data around, and is hidden from the user by the protocol layers that come in between (just as you don't need to know how a telephone system works in order to use it). "MAC" is most frequently used to refer to the "MAC Address", which is a unique 48-bit identification code built into every network adapter module. In theory no device in the world has the same MAC address as any other, so every device can be identified individually, but at some point addresses will run out. See also TCP/IP.​

    MiB
    (No, not "Men in Black"!) See KiB

    MSP (deprecated)
    Modified Software Project - A term coined to encompass the beaverings of the BYTs (the custom firmware, software packages, and support resources). Fallen into disuse due to lack of support. See CF.​

    Multiplex, Mux
    The point about digital transmission, be it terrestrial or satellite, is that a number of services can be transmitted on one frequency (instead of the old days of analogue, when only one service occupied the whole of the frequency). The process of sharing multiple data streams over one transmission channel is called "multiplexing", and a transmission channel carrying multiple services is called a "multiplex" (abbreviated to "mux"). See also LCN.

    .​
     
    Last edited: Oct 19, 2017 at 9:42 AM
    Daniel and 4291 like this.
  4. Black Hole

    Black Hole Felonius Gru

    NAS
    Network-Attached Storage - an external hard disk drive accessed by an Ethernet connection instead of a USB cable. This means its content can be accessed by anything on the network, not just the PC it happens to be plugged into, and doesn't rely on the PC being turned on. See also NFS and SMB.​

    Netiquette
    I'm not about to start a lecture on the thorny subject of the dos and don'ts of on-line behaviour, especially as the Hummy.tv forum is on the whole a very genteel place and everyone seems to know how to behave. Rather, this is about the common abbreviations (not specific to the subject of the HD/HDR-FOX) that slip in from time-to-time, even the most dogged of acronym-haters will write one occasionally, and will have to read them like them or not. Instead of scattering explanations through this technical glossary, I've gathered together a list here, which will no doubt expand with time.

    It is worth noting however, that to emphasise text by TYPING IN UPPER CASE, PARTICULARLY MORE THAN THE OCCASIONAL WORD OR ACRONYM, IS THE TEXT EQUIVALENT OF SHOUTING and seen as rude (see what I mean?). There are other ways of emphasising text, such as emboldening, italicising, and underlining (or combinations thereof). There are tools for these in the WYSIWYG post editor, or if you are working in plain text there is help available HERE (click).​

    AFAICR - as far as I can remember
    AFAIK - as far as I know - which is not the same as "to my (certain) knowledge"
    BICBW - but I could be wrong
    BTW - by the way
    FUD - fear, uncertainty, doubt
    FWIW - for what it's worth
    FYI - for your information
    HTH - hope this/that helps
    IIRC - if I remember correctly
    IMO/IMHO - in my (humble) opinion
    LOL - laugh out loud (has also meant "lots of love", but less so these days). Also ROFL (roll on floor laughing) and LMAO (laugh my arse off), and many ruder ones I don't expect to see in these parts.
    LMAO - see LOL
    OH - see SWMBO
    OP - original post/poster
    ROFL - see LOL
    SWMBO - she who must be obeyed (ie the boss of the house), this is a direct quote from John Mortimer's Rumpole series. Also OH (other half).
    TBH - to be honest
    YMMV - your mileage may vary (from the experience reported). For "mileage" read "results" (or "experience").
    See also Newbies' Guide to the Hummy.tv Forum (click).​

    NFS
    Network File System - a communications protocol for accessing file storage via a network, favoured by Linux and Apple. See also NAS and SMB.​

    NTFS
    New Technology File System - NT as in Windows NT, the basis of modern Windows (as opposed to the Win3.1 - Win98 - WinME product line). This is a method for arranging data on a hard drive, the other main one from the PC point of view being FAT32. NTFS does not suffer the file size limits of FAT32. A Windows PC can access a NTFS drive no problem, Linux can now but used to have trouble, but the Humax (without modified software) can only read from an NTFS drive - it can't write to it. The CF has now improved this, so that when plugged in an NTFS external drive is automatically detected and has full read/write access. See also FAT32 and Ext3.​

    OTA
    Over The Air - the automatic firmware update process which uses the digital TV channels (HD channels in the case of the HD/HDR-FOX T2) to send updates to suitably connected equipment without user intervention. This is a key aspect of the digital TV roll-out, and also gives the authorities a controlling hand (if they decide to use it) over how our TVs and set-top boxes behave. Note that a CF package exists to disable OTA updates.​

    PCM
    Pulse Code Modulation. This is a means to represent an analogue signal (eg an audio waveform) by a digital data stream.

    Pulses, in which the signal level is one of only two values (described as "0" and "1"), are at the heart of all digital transmission schemes. The advantage of digital over analogue (where the value can be anything between a minimum and a maximum) is that the receiver only has to discriminate between two values, so if the transmission medium is very "noisy" (ie imposes a lot of random fluctuations on the signal), as long as the difference between a 0 and a 1 remains greater than the noise, the receiver can still recreate a reasonable representation of the pulses that were transmitted, whereas an analogue signal sent in the same way would be overwhelmed by the noise.

    Any method which transforms a signal from one representation to another is described as a "modulation". Typically there is a modulator which converts the signal for transmission, and a demodulator which converts it back at the receiving end. For example: FM radio modulates the audio signal onto a radio wave by shifting the frequency of the radio wave in proportion to the instantaneous value of the audio signal - hence "frequency modulation" (FM), and the receiver picks up the radio wave and uses the frequency shifts to recreate the audio signal (ie the sound produced by the loudspeaker).

    The FM scheme is a linear modulation: the frequency shift is directly proportional to the analogue input level. There are (at least) two linear modulation schemes using pulses: Pulse Width Modulation (PWM) and Pulse Position Modulation (PPM). PWM uses a regular stream of pulses, but the duration of each pulse (ie its "width" when illustrated in a plot of signal voltage against time, as would be seen on an oscilloscope) represents the signal. PPM shifts the position of a constant-width pulse within the time period allocated to each pulse (little used). Radio controlled models use PWM to convey the joystick control signal to the servo motors in the model (and modulate the PWM onto a radio channel using FM).

    PCM is a modulation using pulses, but instead of being a linear modulation, uses the pattern of the pulses in each time period to represent a binary number - the number itself representing the signal level of the input waveform (ie digital). This is the simplest form of digital representation, and is the method used to encode the audio signal in .WAV files, on CDs, and over HDMI (also known as Linear Pulse Code Modulation - LPCM - because each increment in digital value represents the same change in signal level).

    In modern systems, PCM is most likely to be used for one or more individual channels within an overall multiplexing scheme for delivering multiple signals simultaneously - eg audio and video. Even a CD has to deliver two PCM channels - the left and right signals of stereo audio, so the multiplexing scheme has to be able to identify and separate the components for the left and right channels.

    PCM carries the direct binary representation of each instantaneous sample of the analogue waveform, and is invariably the start and end point of any digital transmission or storage of a real-world signal. Compression techniques can reduce the storage requirements (or transmission bandwidth) needed for any particular signal, by an encoder removing repetitive or irrelevant aspects of the data (in a way that still enables a reasonable facsimile of the original signal to be reconstructed by the decoder at the receiving end). Thus PCM representing an audio signal may be encoded to MP3 for storage or transmission, or video encoded to H.264. The fact that these have to be encoded from PCM at the input, and decoded to PCM at the output, tends to be ignored.

    A good description of the technical detail of PCM (and the distinction between LPCM and non-linear forms of PCM) can be found here: https://wiki.multimedia.cx/index.php/PCM

    Pi

    See RPi

    Pixel
    Picture Element - one dot in a series of dots which build up the picture on a video display. Pixels are usually (but not always) square, arranged in rows and columns (for example: 1080 rows of 1920 pixels each makes a 1080i/p "Full HD" TV picture). The process of building up the picture is to send information defining the brightness and colour of each pixel to the display, row by row and column by column. The arrangement of rows to make up the display area is known as a "raster". In a video display (eg a TV) each pixel is made up of red, green, and blue sub-pixels. Knowledge of the exact way the sub-pixels are arranged can be used to increase the apparent resolution of the screen (eg Microsoft's ClearType technology). Some displays use a completely different arrangement: eg projectors based on the Texas Instruments DLP light modulator have a diagonal matrix of diamond-shaped pixels (squares rotated 45°), and use image processing to map the incoming signal (which expects a normal raster of square pixels) onto the actual display. See also Colour Space.​

    PRID / P-CRID
    Programme Reference IDentifier - Unofficial, see CRID.​

    PVR
    Personal Video Recorder - Traditionally, a broadcast video recorder that records programmes to an internal memory/hard drive rather than a removable disc (eg DVD-R) or tape cassette, therefore the recording is only available personally.​

    Raster
    See Pixel.​

    Repo
    Repository - Humax uses Linux as its operating system, the key property that makes the CF much easier than it might otherwise be. The Linux world uses "package management" to handle downloadable applications and their revision, and the CF has tapped into those facilities for the applets that make it up, installable via the web interface, mix-n-match according to what the user will find useful. The package management accesses an on-line repository, where the project packages are made available for download.​

    RGB
    See Colour Space.​

    RMA
    Contrary to common misunderstanding, RMA stands for Return of Materials Authorisation - the docket used to authorise the Goods Inwards department to receive a warranty return, not "Return to MAnufacturer". As an acronym (or for the pedantic: initialism) it's in wide circulation but should never have got into the wild, being an internal administrative process and not something to trouble the customer with. Typically, when you negotiate a warranty return with a company, the Customer Service people will log an RMA and issue you with a reference number to enclose with the item. Goods Inwards (where deliveries are received) have to check everything received against the respective paperwork: eg items ordered are checked against the purchase order; or in this case the RMA reference number against the RMA form that Customer Services registered. Goods received without any accompanying paperwork will get rejected (or at the very least will go into limbo).​

    RPi / Pi / Raspberry Pi
    A small, cheap, bare-bones computer developed to put computer programming back into the hands of the individual (primarily intended for education, but now appealing to hobbyists in general). Programming for main-stream commodity computers has become very sophisticated and too complex for novices; the RPi represents a modern-day version of the Sinclair ZX80/ZX81/Spectrum which can be hooked up to a TV and fiddled with, without fear of "breaking" the family computer. Using a relatively low power processor integrated with memory and video, the RPi can run several versions of Linux from a memory card, hook up to a keyboard and mouse via USB ports, and use a TV for output via HDMI. It is so cheap that an RPi can be used to provide the "brains" in a custom project, and the ready-made hardware and software environment it provides bypasses the need to design and build hardware and lets the development get straight down to the programming. When installed with a media player package such as XBMC, an RPi can be dedicated to being a streaming media client and used as a set-top box controlled with a IR remote.​

    Samba
    Windows PCs can share their drives over a network so that the PCs can access the files on a remote PC as if they were on the local PC. The Linux method for sharing drives (compatible with Windows shares) is Samba. With the CF installed on the Humax, Samba can also be installed and that makes the files on the Humax directly accessible from Windows PCs across the network, just like a local file. This means that any media player compatible with the .ts file format (once decrypted) can play the file regardless of DLNA, and fast-forward/rewind will work. In order to access a Windows file share from the Humax, you need the CIFS package. See also SMB.​

    SCART
    Radio and Television Receiver Manufacturers' Association (in French) - Basically the chunky 21-pin connector that was used to connect AV equipment before HDMI came along. The Humax simultaneously outputs video and audio digitally on the HDMI, and to conventional analogue TV standards on the SCART and the phono connectors (composite video or RGB, plus stereo audio). If you have an analogue DVD recorder, the SCART is probably the quickest way to copy a programme from the Humax to disc - the alternatives being a time-consuming process of decrypting and copying the content to a PC, then converting the file format to suit a DVD and burning it. See also HDMI.​

    SD / StDef
    Standard Definition - By StDef we mean the content recorded from the Freeview non-HD channels. See also HiDef.​

    SMB
    Server Message Block - a communications protocol for accessing file storage via a network, favoured by Windows. See also NAS, NFS and Samba.​

    Software
    See Firmware v. Software.​

    S/PDIF
    Sony/Philips Digital Interconnect Format - This is a means of sending high-quality audio (including surround sound) as digital data between (say) a Blu-ray player and a surround sound decoder/amplifier, and can be either coaxial cable or fibre optic. Fibre has the advantage of there being no possibility of setting up a ground loop and creating hum at the speakers. Coax connectors can be RCA (phono) or BNC (bayonet), fibre connectors are usually TOSLINK (Toshiba Link). Note that the bandwidth of S/PDIF is only sufficient for surround sound in a compressed data format; HDMI is capable of lossless surround sound (although whether anybody would notice is another matter). See also Surround Sound.​

    SRID / S-CRID
    Series Reference IDentifier - Unofficial, see CRID.​

    Station / Service
    See LCN.​

    STB
    Set-Top Box - an add-on piece of equipment, commonly used to provide cable, satellite, or Freeview reception to a TV not otherwise suitably equipped. Neither modern flat-panel TVs, nor to a lesser extent the last generation of blobby black or silver-grey CRT TVs, provide a convenient shelf (unlike the furniture-built TVs previously), but none-the-less it is still referred to as a set-top box!​

    SUI
    Standard User Interface - to distinguish from the custom firmware's web browser interface (WebIF), SUI refers to the normal remote control (or front-panel controls) and TV screen menus that are accessible with or without the custom firmware installed. See also WebIF.​

    Surround Sound
    Some Freeview TV programmes (on the HiDef services) are broadcast with multi-channel audio (meaning more than two - ie stereo - channels). DVD and Blu-ray are capable of six or eight audio channels. Traditional stereo provides limited spatial sound by placing the apparent audio source to the left or right of the sound field (or somewhere in between). By having loudspeakers placed to the left and right of the TV screen, the sound can appear to come from the same place as the object in the picture. Surround provides for more loudspeakers to be placed to the sides and the rear of the viewer, so that sound effects for things off-screen (eg an approaching vehicle) can be emitted from the appropriate direction and appear to move (the same technology is used in cinemas). One channel is reserved for low frequency audio to be sent to a specialist loudspeaker designed for the purpose of producing gut-shaking bass, and as the human auditory system cannot tell where these low frequencies come from one channel is sufficient. Thus we get "5.1" (front right, front left, front centre, rear right, and rear left, plus low frequency "sub") and "7.1" (as per 5.1, plus side right and side left). Typical scenarios are for a TV or DVD/Blu-ray player to be connected to a "home theatre" multichannel decoder/amplifier + loudspeakers by HDMI or S/PDIF; some players have multichannel loudspeaker outputs built in. The HD-FOX/HDR-FOX can be connected to the TV by HDMI and an amplifier by S/PDIF, or the TV can pass on the HDMI sound to the amplifier by S/PDIF, or the HD-FOX/HDR-FOX can be connected by HDMI to the multichannel amplifier, which taps off the sound data and passes on the HDMI to the TV. For surround sound output, the HD-FOX/HDR-FOX must be set to "Multi-channel" in the audio preferences (but this won't create surround sound for a programme broadcast in stereo). See also S/PDIF, Dolby.​

    TCP/IP
    Like building a house by placing a roof on top of walls on top of a foundation, digital communications are built by starting with something simple as a foundation and adding layers of sophistication on top. The actual wires (or wireless!) and electronics is the "physical layer", and there can be many types. The means to communicate between physical devices so that each device responds to data that is sent to it is defined by the MAC layer, and so on. Each layer adds specific functionality, and hides the details that are underneath from the layers that are above, so that the designer can actually have a completely different communications system in the lower layers without affecting how the upper layers operate (eg the difference between wired Ethernet and WiFi - obviously different and with different problems to overcome, but the user is unaffected). Transfer Control Protocol (TCP) is the top layer but one, and defines methods for sending a complete packet of data from one place to another, and defines how packets that arrive in the wrong order (having been routed over different paths) or gone missing on an unreliable transmission medium are dealt with (an alternative is UDP - User Datagram Protocol - which is faster when the link is a reliable medium, or sometimes it is more important to get the data quickly than reliably). Internet Protocol (IP) is the top layer, which handles the addressing and delivery. Combined, the right choice of protocols enable devices at each end of world-wide interconnected networks to find each other and communicate reliably, and the Internet as we know it is built on TCP/IP. See also MAC.​

    Telnet
    This is a means to log-in to a command console in Linux (similar to the DOS command window in Windows; Linux is the operating system running on the Humax) from a remote network connection. To do so requires a Telnet client running on the local machine (typically PuTTY running on a Windows PC, although Win7 and possibly others have a built-in Telnet client that can be enabled and used).​

    TOSLINK
    Toshiba Link - See S/PDIF.​

    TS, .ts
    Transport Stream - this is the "file type" of a video file recorded on the Humax, and each recording comprises a set of four files (three in the case of a radio recording) - all with the same name but having different file types, the important one being the .ts. Pressing the "Media" button on the handset lists the file sets, but to see the individual files requires exploring the Humax drive by FTP. Note that the .ts files as recorded by the Humax are encrypted, and if copied by FTP they remain encrypted. Decrypting the files requires a copy to be performed by the Humax menus onto an external drive (or a virtual drive if using the modified software, network drives in the future), and in the case of HiDef .ts files only after first clearing the Enc flag in the recording's file set (see Foxy). Files are also decrypted on-the-fly when being streamed to a DLNA client. HD-FOX T2 owners should note this only applies to the HDR-, or the HD- if running the HDR firmware - the unmodified HD-FOX T2 has no means to decrypt the files.​

    TV
    Television or Television Set (for completeness).​

    UHD
    Ultra-High Definition - This is a new standard for TV which increases the display resolution beyond 1920x1080 pixels ("2K") to "4K" (3480x2160) or even "8K" (7680x4320). This results in the possibility of much larger TVs (viewed from a normal distance) without the pixellation in the image becoming obvious, and/or finer detail in the image.

    Upgrades to the TV transmission system may eventually result in a UHD TV service, but it is anyone's guess whether TVs purchased now will be compatible with it. Meanwhile you can expect Internet TV services (such as Netflix) to stream UHD content, and content to be playable from Blu-Ray etc. However, artificial image upscaling performed by the TV itself on StDef or (normal) HiDef can result in a better viewing experience on large (60" upwards) TVs.

    See also HDR.​

    UHF
    Ultra-High Frequency - the waveband in the electromagnetic radio spectrum from 300MHz to 3GHz. UK TV transmissions are in the UHF band from about 450MHz to 900MHz. Down-converted satellite signals are in the region of 1-2GHz. The satellite signals themselves (unconverted) are around 10GHz (in the microwave band).​

    UPD
    In the absence of a universal term for these things, "UPD" is coined as a contraction of USB Pen Drive. Variously known as a "USB stick", "pen drive", "thumb drive" (etc, as many different euphemistic terms as a remote control handset), these are the solid-state non-volatile mass-storage devices that plug into a PC's (or the Humax's) USB socket to provide off-line data storage. Some prominent members of this forum criticise its use however.​

    UPnP
    Universal Plug-and-Play - A set of standards which provide the self-configuration we enjoy with our computer equipment these days. Remember when it used to be necessary to install and configure some kind of driver before anything would work at all? No?? You don't know you're born! These days, plug in a UPD or a printer, chances are the operating system will think for a little while and then the device is ready for use. USB UPnP standards are responsible for this, the hardware in the device is able to identify itself on request, then the operating system configures built-in drivers to deal with it. DLNA provides UPnP across a network, so for example a media streaming client is able to locate a server on the network without human intervention. See DLNA.​

    USB
    Universal Serial Bus - the (currently) ubiquitous socket for connecting peripherals to PCs, or in our case for connecting an external storage device (memory stick or portable hard drive) or a WiFi dongle to the Humax. The HDR-FOX T2 has two USB sockets: one on the front under a flap, and one on the rear immediately below the Ethernet socket. A keyboard can be connected too, although the functionality is severely limited.​

    VFD
    Vacuum Fluorescent Display - the display technology used for the front panel information display of the HDR-FOX T2. It has the advantage over LCD (Liquid Crystal Display) of generating its own light (LCD needs ambient light or to be provided with rear illumination), and over LED (Light Emitting Diode) of being able to have pre-defined icons and also be predominantly white (with a green tinge). In the HDR-FOX the VFD is covered by an orange filter to produce a dim orange display, presumably with the intention of being fairly subtle in dim lighting. Some people have removed the filter (reported to be easy to do once the box is opened up) and prefer the brighter greenish display. The display on the HD-FOX T2 is LED.​

    WebIF
    Web InterFace - this is the control panel for the CF, accessed using a web browser on your favourite PC or other computing device across your home network (in order to use the WebIF, it is necessary that your Humax is connected to your network). See also SUI.​

    YCbCr, YPbPr, YUV
    See Colour Space.​

    .
     
    Last edited: Oct 19, 2017 at 10:16 AM
    4291 likes this.
  5. Black Hole

    Black Hole Felonius Gru

    (reserved space)
     
  6. Black Hole

    Black Hole Felonius Gru

    (reserved space)
     
  7. PH22

    PH22 New Member

    Extremely helpful thread/post - many thanks Black Hole. Just one question arising regarding transfer of files: Can you transfer complete FOLDERS to a FAT/FAT32 external Hard Drive from the HDR, providing each FILE within the FOLDER is less than 4GB, even though the total FOLDER size itself may be more than 4GB?

    Thanks

    Regards
     
  8. Black Hole

    Black Hole Felonius Gru

    I don't see why it shouldn't work. Copying a folder is a recursive process made up of a series of individual file copies.
     
  9. af123

    af123 Administrator Staff Member

    As far as I know (although I can't remember where I found this), HDF is Humax Download Format
     
  10. Black Hole

    Black Hole Felonius Gru

  11. ChrisDaniels

    ChrisDaniels Well-Known Member

    Yep I remember it was in a German document we found before the hacking got started.
     
  12. fenlander

    fenlander Active Member

    You might want to remove the note about the 4GB bug in Samba as the latest update has fixed this.
     
  13. Black Hole

    Black Hole Felonius Gru

    Verified?
     
  14. fenlander

    fenlander Active Member

    It certainly works for me, and others have also confirmed.
     
  15. Black Hole

    Black Hole Felonius Gru

    Right-ho.
     
  16. af123

    af123 Administrator Staff Member

    I just copied and pasted this over to the Wiki (http://hummypkg.org.uk/wiki/Glossary_Of_Terms) to see how it looks, hope you don't mind. It looks pretty good :) Not sure what to do about attribution though, particularly if you wish to maintain it there rather than here. I've added a link back at the top of the page for now. Of course anyone can edit it once it is on the Wiki. Although it is possible to protect certain pages, it isn't usually recommended.
     
  17. Black Hole

    Black Hole Felonius Gru

    I was wondering about duplicating it on the Wiki, but I'm not keen on keeping both updated. Mind you, it is pretty much complete. Ish.

    I can see I'm going to have to reinstate some formatting.
     
  18. Black Hole

    Black Hole Felonius Gru

    I have made a few additions / corrections lately, anybody who hasn't looked at the Glossary lately might want to have a browse.
     
  19. Black Hole

    Black Hole Felonius Gru

    DVB and LCN added.
     
  20. trellis

    trellis New Member

    In answer to the query: Yes, RGB is available on the SCART.

    HTH