• The forum software that supports hummy.tv has been upgraded to XenForo 2.3!

    Please bear with us as we continue to tweak things, and feel free to post any questions, issues or suggestions in the upgrade thread.

Interesting Items...

Black Hole said:
Because I, for one, have my Humii set to stereo output not multichannel.
Click to expand...

Had you said so, at least your post would have made some sort of sense, though I still can't see the point of it. Nobody ever said there was an issue pcm audio. Some of us have decent sound systems. Using a flat screen TV for audio is not usually a pleasant experience :oops:
 
Equally I don't understand the relevance of your comments. The article I have brought to everyone's attention is, I believe, interesting and material. My commentary explains that people with audio output setting as stereo (either because they need to sidestep the volume control problem, or because they don't care about multichannel) won't have observed the audio problem the article reports.

It matters nothing that you in particular don't use the stereo setting. All you've done is confuse the issue.
 
grahamlthompson said:
Pretty sure all Humax boxes convert aac to ac3 unless you turn off surround sound in the box TV setup.
Click to expand...
This implies the box is capable of transcoding an audio stream in real time, and with minimal latency, unless AC3 is just a repackaging of AAC. Really? It seems far more likely that it simply passes through whatever comes in. (PCM doesn't require re-encoding, just decoding.)
 
Black Hole said:
This implies the box is capable of transcoding an audio stream in real time, and with minimal latency, unless AC3 is just a repackaging of AAC. Really? It seems far more likely that it simply passes through whatever comes in. (PCM doesn't require re-encoding, just decoding.)
Click to expand...

Well recordings have AAC audio, AV receiver states ac3 (2,0 or 5,1) is being recieved from live or recording playback using HDMI audio. So it must be transcoding. AAC played back using a media player says it's AAC. HDR FOX T2 HD recordings copied to Foxsat-HDR have no audio , unless you replace the AAC with AC3 audio before using AV2HDR.

There is no PCM source to pass through. SD channels use the lossy mpeg 1 layer 2 codec, The box transcodes to pcm for digital audio output.

Back in the early days of Freeview-HD the late adoption of AAC audio caught out some box makers. As a result those using a TV or a AC receiver without a suitable decoder got no audio.
 
Last edited:
Black Hole said:
PCM is only uncoded data converted to serial, so I don't regard this as transcoding - only decoding. "Pulse Code Modulation" simply means serial data.
Click to expand...

PCM is a sampling of a complex waveform expressed as a digital number. The higher the sampling rate the closer to the original waveform when the digital data stream is converted back to a analogue waveform. A CD has this digital data, copying this data to a WAV file is a lossless conversion. Broadcast SD audio is entirely different. It is compressed in the same way as video using lossy mpeg compression, it has to be decoded and converted to a PCM stream. A recording of a SD programme has a MP2 compressed audio track multiplexed onto the data. It has to converted to pcm on playback or from the live programme so that it can be used with TV's and other kit.
 
PCM is a serialised decode of the broadcast/recorded audio stream, for sending over HDMI - not a transcode. To create AC3 from AAC requires a decode of the AAC and then a re-encode to AC3, ie a transcode - I'm not saying it's impossible, but I very much doubt the HD- or HDR-FOX has enough horsepower or hardware support to perform the encoding without introducing a noticeable delay in the audio (lip sync errors). There is of course hardware support for decoding, which is a much simpler process.

Your position seems to stem from your belief in what your audio kit is telling you: that the audio stream from the HDR-FOX over HDMI when receiving/playing HiDef with multi-channel audio selected is AC3. I suggest it is mistaken, unless the broadcast itself is AC3 (which it is for satellite).

Besides, it makes sense for the HDR-FOX to pass through AAC or decode to PCM - a TV capable of HiDef reception will be able to handle AAC for sure, and if it isn't HiDef-capable there's PCM to fall back on.
 
Last edited:
Black Hole said:
PCM is a serialised decode of the broadcast/recorded audio stream, for sending over HDMI - not a transcode. To create AC3 from AAC requires a decode of the AAC and then a re-encode to AC3, ie a transcode - I'm not saying it's impossible, but I very much doubt the HD- or HDR-FOX has enough horsepower or hardware support to perform the encoding without introducing a noticeable delay in the audio (lip sync errors). There is of course hardware support for decoding, which is a much simpler process.

Your position seems to stem from your belief in what your audio kit is telling you: that the audio stream from the HDR-FOX over HDMI when receiving/playing HiDef with multi-channel audio selected is AC3. I suggest it is mistaken, unless the broadcast itself is AC3 (which it is for satellite).

Besides, it makes sense for the HDR-FOX to pass through AAC or decode to PCM - a TV capable of HiDef reception will be able to handle AAC for sure, and if it isn't HiDef-capable there's PCM to fall back on.
Click to expand...

Don't you ever bother to do the slightest bit of research before posting ? :oops:

http://www.bbc.co.uk/blogs/bbcinternet/2010/06/questions_around_surround_soun.html

So the answer does lie in the need for the receiver to either transcode to a suitable format such as Dolby AC-3 or DTS or to output multi-channel linear PCM. Earlier versions of the UK D Book were only able to recommend the presence of transcoding. But now that transcoding solutions are becoming available the UK is no different from all other European standards. No doubt receiver manufacturers are working hard to incorporate these into their products.
Click to expand...

Your other assertion re TV's is also a fantasy.

From the spec of my twin Freesat twin Freeview Panasonic AS802B TV

External Equiment Valid Input Signals for HDMI.

2ch Linear PCM (Sampling 48kHz,44.1kHz, 32kHz).

No other audio input by HDMI is supported.
 
Last edited:
Out of interest I sorted out a 108op24 download with AAC 5.1 audio.

Played back from USB on HDR1000S, audio output was ac3 5.1 Video 1080p25 , on HDR FOX T2 audio multichannel pcm Video 1080p25 and LG Bluray player Audio multichannel pcm and video 1080p24.

Christmas recording of Doctor Who from HDR FOX T2 See attached image.
 

Attachments

  • DRWho.jpg
    DRWho.jpg
    143.5 KB · Views: 12
grahamlthompson said:
Don't you ever bother to do the slightest bit of research before posting ? :oops:

http://www.bbc.co.uk/blogs/bbcinternet/2010/06/questions_around_surround_soun.html
Click to expand...
Fair enough, but it's well buried.

grahamlthompson said:
From the spec of my twin Freesat twin Freeview Panasonic AS802B TV

External Equiment Valid Input Signals for HDMI.

2ch Linear PCM (Sampling 48kHz,44.1kHz, 32kHz).

No other audio input by HDMI is supported.
Click to expand...
Does that apply to all TVs or just yours? If only PCM is acceptable over HDMI then clearly no form of multi-channel audio would be practicable.

All I can say about audio transcoding in the HDR-FOX is that I haven't seen anything in it that would be capable of doing the job (although it could be buried in a DSP in the SoC)... but I am very surprised that it is possible without significant delays in the audio path. We can assume the encoding is frame based (not video frames), and each frame would have to be long enough to contain enough waveform data to compress. Therefore, to transcode, a whole frame needs to be accumulated, decoded, re-encoded, and sent on, and then the renderer has to accumulate the frame and decode it. Even if the decoding/encoding is instant (which it isn't), there's an extra two frame buffer times in the delay path.

If a frame is 1024 samples (which I think it is), that's 25ms of audio, and at least 50ms additional delay in the audio path compared with simply decoding the audio once at the renderer. The lip sync setting only delays the audio further - not speed it up.

Yes, I admit I am pontificating without any hard knowledge. However, the more I think about it the more problems I can see and the more amazing it is if anyone has cracked them. And all this started from an article about how somebody cocked it up.
 
Black Hole said:
Fair enough, but it's well buried.


Does that apply to all TVs or just yours? If only PCM is acceptable over HDMI then clearly no form of multi-channel audio would be practicable.

All I can say about audio transcoding in the HDR-FOX is that I haven't seen anything in it that would be capable of doing the job (although it could be buried in a DSP in the SoC)... but I am very surprised that it is possible without significant delays in the audio path. We can assume the encoding is frame based (not video frames), and each frame would have to be long enough to contain enough waveform data to compress. Therefore, to transcode, a whole frame needs to be accumulated, decoded, re-encoded, and sent on, and then the renderer has to accumulate the frame and decode it. Even if the decoding/encoding is instant (which it isn't), there's an extra two frame buffer times in the delay path.

If a frame is 1024 samples (which I think it is), that's 25ms of audio, and at least 50ms additional delay in the audio path compared with simply decoding the audio once at the renderer. The lip sync setting only delays the audio further - not speed it up.

Yes, I admit I am pontificating without any hard knowledge. However, the more I think about it the more problems I can see and the more amazing it is if anyone has cracked them. And all this started from an article about how somebody cocked it up.
Click to expand...

Obviously I can't speak for other TV's. except to say it's an advanced modern smart TV, the next one up in the same series is 4K. I imagine the TV simply tells any hdmi source to output stereo pcm. That could well be why most TV's will not output surround sound using arc, when it's input from an external source into a TV HDMI port, hence the reason for requiring S/Pdif connections to a sound bar if surround sound is required. Presumably the TV's that do have ac3 passthrough. The obvious answer to your sync issues is simply delay the video accordingly. 100% sure the HDR FOX T2 does output ac3 from both S/Pdif and HDMI outputs. If it did not there would be no output from my cordless headphones when set to DD decoding.
 
Electronics Weekly 24/08/2016 said:
The ringmaster of Seoul

The memory industry is becoming as exciting as it used to be in the 1980s when the US was fighting against the Japanese while the Koreans prepared a massive assault – simultaneously building fabs and products for the 64k, 256k and Mbit generations.

Thirty years on, and the leading-edge is no longer kbits, Mbits or even Gbits but a mighty Tbyte of non-volatile storage in a BGA package weighing one gram, which is promised for next year by Samsung, which seems to have taken the technology lead in 3D NAND.

Five hundred and twelve 256Gbit three-bit/cell (‘TLC’) 64-layer chips in a 16-layer stack will go into its tiny frame. It will read sequentially at 1,500Mbyte/s and write sequentially at 900Mbyte/s. Samsung will put 32 of its Tbyte gems into a single solid-state drive (SSD).

This is setting a high bar, which Intel, Toshiba/Western Digital and Micron seem some way below.

Toshiba/WD says it is in pilot production of 64-layer 256Gbit chips, but Intel and Micron have to up their game from their current 48-layer products by the end of next year if they’re to stay in the running.

Thirty years ago, as now, Intel was losing money in the memory business. Next year will be crunch-time, with much depending on whether the company can ramp 3D cross-point (‘3D XPoint’) production and whether this will find customer acceptance.

Hovering menacingly in the wings Yangtse River Storage Technology is gearing up to make 3D NAND – but at what density in terms of layers or storage capacity, with what levels of reliability, yield, performance or production capacity no one knows.

Meanwhile the Samsung ringmaster in Seoul cracks the whip and sets the pace. “We want 100Tbyte SSDs by 2020”, it says .
Click to expand...
 
Last edited:
"

SanDisk has a new memory card with more storage space than many computers. Parent company Western Digital announced a prototype one terabyte (TB) SDXC card at the Photokina trade fair in Cologne, Germany on Tuesday.

The spacious new card comes two years after SanDisk unveiled the first 512 GB SD card at Photokina 2014. It also represents the culmination of sixteen years of progressively more efficient storage dating back to the introduction of the first SanDisk 64 MB SD card at the turn of the century.

“Just a few short years ago the idea of a 1 TB capacity point in an SD card seemed so futuristic – it’s amazing that we’re now at the point where it’s becoming a reality. With the growing demand for applications like VR, we can certainly use 1 TB when we’re out shooting continuous high-quality video,” said Sam Nicholson, CEO of Stargate Studios and member of the American Society of Cinematographers, in a release from SanDisk.

The company says its new high capacity card will help in a data-intensive age of virtual reality, video surveillance, 360-degree video and resolutions up to 8K.

Exactly when the 1 TB card will be available and how much it will cost has not been announced. But to give some indication, when the 512 MB card was first unveiled two years ago the recommended retail price was originally US$799. It has since dropped to $599 and can easily be found elsewhere online today for $299 (10,500 baht)."

Source: SanDisk
 
I can't figure out how this works. Scanning the laser beam produces a 2D drawing the same as disco light shows, onto a projection surface. Somehow, these guys have found a way to create a projection surface in free air, and sweep the position of that surface through the volume - which, when coordinated with the laser scanning, provides addressable pixels in 3D space.

What is the form of this projection surface? It needs to interact with the laser beam in such a way that it disperses the laser light in all directions (or at least all viewable directions), and it seems to be transparent (or exists in a non-transparent form for only a short time, so you don't really notice it).

The array at the base is something to do with creating the projection surface, and blocking it disrupts the surface (as shown in the video). Is it an array of ultrasonic transducers? I'm not aware that an ultrasonic field in air can cause such a great change in refractive index to produce this effect - but the proof of the pudding is in the eating, as they say. Whatever it is, it has to appear and disappear very quickly, so I don't think it could be a mist of droplets or anything like that.

It's limited to wire-frame renders because the laser can't be scanned fast enough to draw a full 3D raster at a non-flickering frame rate (or would be too dim if it did), the same as early laser projectors couldn't be scanned fast enough to produce a 2D raster and were limited to line drawings.

However they've done it, it's really cool (but it isn't a hologram, whatever they say)!
 
I don't think the ultrasonic pattern has to come and go quickly, it just needs to produce a 3D screen of pixels with varying RI which can be static. The laser then does the 50× per second work.
At least that's my take on it.
 
Don't you think the "screen" needs to scan through space (z) as quickly as the laser can scan in x and y? I see no other way of defining where (along the laser beam) the bright dot appears.
 
You must log in or register to reply here.
Back
Top