1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

BBC iPlayer Quality

Discussion in 'Freeview' started by MontysEvilTwin, May 22, 2016.

  1. MontysEvilTwin

    MontysEvilTwin Well-Known Member

    I downloaded a programme earlier from iPlayer using a HDR-FOX T2. The quality was set to 'High Definition' - the 'HD' symbol was highlighted in the i-panel. Here is the media information:
    Code:
    Metadata:
        major_brand     : M4V
        minor_version   : 1
        compatible_brands: isomavc1mp42
        creation_time   : 2016-04-18 18:21:46
      Duration: 01:27:32.04, start: 0.001333, bitrate: 1821 kb/s
        Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p(tv, bt709), 960x540 [SAR 1:1 DAR 16:9], 1688 kb/s, 50 fps, 50 tbr, 50k tbn, 100 tbc (default)
        Metadata:
          creation_time   : 2016-04-18 18:21:46
          handler_name    : ETI ISO Video Media Handler
          encoder         : Elemental H.264
        Stream #0:1(eng): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 125 kb/s (default)
    Here is the media information from tbe previous episode of the same series downloaded a few weeks ago:
    Code:
    Metadata:
        major_brand     : M4V
        minor_version   : 1
        compatible_brands: isomavc1mp42
        creation_time   : 2016-04-11 17:42:38
      Duration: 00:58:36.00, start: 0.018667, bitrate: 2396 kb/s
        Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1280x720 [SAR 1:1 DAR 16:9], 2297 kb/s, 25 fps, 25 tbr, 25k tbn, 50 tbc (default)
        Metadata:
          creation_time   : 2016-04-11 17:42:38
          handler_name    : ETI ISO Video Media Handler
          encoder         : Elemental H.264
        Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 93 kb/s (default)
    The more recent download is of lower resolution and bitrate (960 x 540 at 1700 kb/s) vs (1280 x 720 at 2300 kb/s) but is 50 frames per second rather than 25. The audio of the recent download is 125 kb/s compared to 93 kb/s for the older recording. How do these changes affect the quality of the recording? Is the lower video resolution and bitrate mitigated by the higher frame rate?
     
  2. gomezz

    gomezz Well-Known Member

    Surely you can see for yourself what the differences are? If you can't then that means the technical differences are irrelevant to your viewing enjoyment.
     
  3. Black Hole

    Black Hole Felinos Guru

    Nonetheless it is strange that two programmes with presumably identical production chains end up stored on the server with different encoding characteristics.
     
  4. ian_j

    ian_j Member

    BBC cost cutting to save server space?

    I downloaded the "... Plays Prince" program in HD and that was nine hundred and something (now watched and deleted so can't check) instead of 1280 x something.
     
  5. MontysEvilTwin

    MontysEvilTwin Well-Known Member

    Was downloading them to watch on a tablet where both look fine. I'd imagine, since 960 x 540 is smaller than 1280 x 720, the difference will be greater the larger the screen. 960 x 540 is called qHD (quarter HD) and is mostly used for high-end smartphones and tablets. The iPlayer site on the HDR-FOX has been updated recently (mostly cosmetic changes to icons etc.) and I was wondering if the Humax servers are now selecting the wrong streams to download?
     
  6. prpr

    prpr Well-Known Member

    It's not even SD (1024x576 when converted to computery square pixels).
     
  7. Luke

    Luke Well-Known Member

    I doubt that.
    Just based on one sample though.

    The Hollow Crown Part 1 1280x720 93kbps 25fps 111.5 minutes = 1.87 GB
    The Hollow Crown Part 2 960x5440 125kbps 50fps 122.0 minutes = 2.18 GB

    That is a 6 1/2% increase per minute for two similar programmes

    But yet appears to take up as much space and bandwidth.
     
  8. Luke

    Luke Well-Known Member

    Content that is still available which was 1280x720 is now available as 960x540 instead.
    I've re-downloaded The Hollow Crown Part 1 to compare exactly the same programme:

    The Hollow Crown Part 1 - creation_time : 2016-04-28 23:39:46 - downloaded 8 May
    1280x720 93kbps 25fps 111.5 minutes, bitrate: 2395 kb/s = 1.87 GB

    The Hollow Crown Part 1 - creation_time : 2016-04-29 01:22:23 - downloaded 22 May
    960x540 125kbps 50fps 111.5 minutes, bitrate: 2298 kb/s = 1.83 GB

    No real saving in space and both versions were generated at about the same time.
     
  9. Black Hole

    Black Hole Felinos Guru

    I guess there's a similar amount of detail in the image, and therefore a similar data rate after encoding (and a similar result once interpolated to 720). Hard to see what the reason for the change might be if the sizes are so similar.
     
  10. grahamlthompson

    grahamlthompson Well-Known Member

  11. Black Hole

    Black Hole Felinos Guru

    This seems to be the relevant paragraph:
     
  12. MontysEvilTwin

    MontysEvilTwin Well-Known Member

    I have a 50 Mbit/s connection and from webif, I know that iPlayer typically downloads at rates between 20-30 Mbit/s on my units. Presumably as the iPlayer version on the HDR-FOX uses discrete profiles (HD, SD or lower quality) rather than an adaptive bit rate (best and normal quality options, e.g. on YouView and Roku boxes) the HD option defaults to the 960 x 540/ 50 fps stream rather than the 1280 x 720/ 50 fps stream.
     
  13. Luke

    Luke Well-Known Member

    Do you think that it is possible that the Youview boxes will still use 1280x720? I have a DTR-T4000 and a DTR-2100 which I could do a visual compare with an HDR- FOX T2, but I wonder which programme would best show up any difference?
     
  14. MontysEvilTwin

    MontysEvilTwin Well-Known Member

    I think that the YouView boxes should be able to access the above profile if set to best quality. I am not sure how to check this though. If you press the information button on your TV while an iPlayer stream is playing it may show the resolution but this is likely to just be '1080P' or whatever the output of your YouView box is set to.
     
  15. Owen Smith

    Owen Smith Active Member

    I had noticed a significant reduction in BBC iPlayer picture quality on the HDR Fox T2 recently. I assumed it was something at the BBC end, now I know what. Damn them and their "subjectively better".
     
  16. MontysEvilTwin

    MontysEvilTwin Well-Known Member

    I would check that the quality is still set to 'HD'. If I remember correctly, a recent update to iPlayer also reset the user settings to the default values.
     
  17. Owen Smith

    Owen Smith Active Member

    Quality is set to HD, you can see before you press Play that's selected the HD version. This is how I noticed the above loss of defaults you mention.

    So is there a way to get the HDR Fox T2 to play the 1280 x 720 25fps iPlayer streams?
     
  18. prpr

    prpr Well-Known Member

    I downloaded something a couple of days ago using get-iplayer in the top quality HD mode and copied it over to the HDR. It plays back with the usual stupid "film-effect" flicker compared to proper telly which doesn't flicker on proper 50 fields/sec interlaced video.
    If this is the best the "future" can bring, then I'll stick with the "present" thanks.
     
  19. Owen Smith

    Owen Smith Active Member

    So when they say 25fps they really mean progressive scan? I assumed 25fps was a "don't confuse the viewing public" shortcut for 50i.
     
  20. prpr

    prpr Well-Known Member

    I don't know. Nobody really wants to define "f" do they? Is it fields or frames?