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Sky HD Demo

Discussion in 'Sky Digital TV Forum' started by Muf, Sep 7, 2004.

  1. Muf

    Muf
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    Has anybody been able to tune in to this demo. I can only hear the audio but no picture (my vpid is showing 000). The audio track has a continuous commentary about HD technicalities and how Sky are ideally placed to take the lead as a HD provider and their customers have proven themselves to be early adopters of new technology. 2006 launch is mentioned.
    Two channels on 19E
    11436 V 22000 5/6
    11671 H 22000 5/6

    Jim
     
  2. Muf

    Muf
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    The transmission on 11671 was switched off just after mid day, it was the same sound track as the 11436 channel. The 11436 channel is still running. The Vid PID seems to be 1FFF with a 3MB/s data rate so it must be MPEG2 and perhaps encrypted because when I enter the Vid PID manually I loose the audio.

    Jim
     
  3. Chris Muriel

    Chris Muriel
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    Yes , it's an odd one.

    My Nokia D-Box (with DVB2000) reports :
    11436V, 22000, 5/6
    VPID=8191, APID=2291, PCRPID=8191. ID=test2

    TSReader (more correctly) shows PID info of :
    VPID=1291, APID=2291, PCRPID=1291

    Now 1291 has a datarate of 5.42 Mbps but
    PID 8191 (0x1fff hex) has 23 Mbps but with MPEG2 null packets.
    PID 1291 is listed as H.264 video (although I haven't been able to decode a binary dump of a recording I made against
    1291).

    That's my findings so far anyway.

    Chris Muriel, Manchester.
     
  4. Abstrakt

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    Please let us know if you find a solution, Chris. I've tried doing the same thing with an AVC/H.264 High Def broadcast I’ve dumped from 5°W, but had no success so far. All I could find out on 5°W was that the AVC/H.264 stream travels over a DVB-IP multicast.

    Cheers.
     
  5. sgauntlett

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    Just to clear this all up. Sky provided the HD demo material but it was encoded and transmitted for the DVB stand at IBC this year. The reason the 11671 service appeared to dissappear is because that transponder was switched to using DVB-S2 rather than DVB-S. The 11436 was a backup transponder using DVB-S in case the DVB-S2 didn't work.

    Basically, the demonstration consisted to two HD channels, both 720p50 material, one encoded in H.264 (the Sky material with audio) and the other encoded with VC-1 (some BBC R&D material shot and editied in 720p50 without audio). VC-1 is the advanced profile Windows Media video standard which is currently being standardized through SMPTE.

    Both 8Mbps channels were being delivered via DVB-S2 (with a total capacity of 54 Mbps per transponder) and received and decoded live in software with 3.2 GHz P4 machines running at 100% CPU!

    Although the video quality wasn't perfect (only using baseline profile H.264 and occaisionally dropping frames from the VC-1), this could allow 6 HD channels per satellite transponder once hardware settop boxes are available.

    Hopefully, those who saw the demonstration realised the potential of this to efficiently deliver HD in Europe.
     
  6. Jonny1973

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    Will Sky use 720p or 1080i ?????

    I know Fox in the states (Sky's American Network) use 720p (which i wouldn't really call Hi-Def). Meanwhile, the BBC have been testing 1080i.

    I hope Sky choose 1080i, since Hi-Def DVD (HD-DVD or Blu-Ray DVD) are both 1080i.
     
  7. Dutch

    Dutch
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    Jonny,

    HD DVD and Blu-ray will probably use 1080p24 to store film-based material, which takes up less space than 1080i60, and of course will give much superior picture quality. Why don't you consider 720p Hi Def?

    Steve
     
  8. beeblebrox12

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    You can't expect to have video without skipped frames if processor load is 100%. Probably the PC hasn't been tuned well for the WM9 test, it should normally do fine without going to 100%.
    I'm actually surprised to read that HD H.264 material has been played back on an HTPC. How was the quality? Or does "baseline profile" mean some kind of downconversion to SD?
     
  9. sgauntlett

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    I can assure you that the PC was tuned extremely well. You have to remember that this 720p was 50Hz and not the 24Hz that you get from WMV HD DVDs. Also it is advanced profile and not the standard encoder which supports 4:2:2 amongst other things, and the PC had to demultiplex the transport stream and this pushed the CPU over the limit. Playing back the wmv file using Media Player 10 (which supports playback of AP WMV) on the 3.2Ghz P4 plays back without frame dropping.

    As for the H.264, there are currently no chips available to do Progressive HD decoding live. I know of a couple that are in the pipeline and should appear before the end of the year but with no hardware decoders, we had to do it in software. Baseline Profile H.264 simply uses P frames (pridictive) whereas moving to Main Profile adds B frames (Bidirectional) and gives a significant improvement in quality. Unfortunately it also means more processing power.

    The demonstration was to show the concecpt of actually transmitting HD using VC-1, H.264 and DVB-S2 giving a chance for Europe to launch HD services using the latest technologies and jump any legacy issues.

    ;-)
     
  10. Abstrakt

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    Thanks for participating in this thread, Sgauntlett! You’ve enlightened many of us on these new technologies, and their potential for delivering high def material. :smashin:

    Is there any chance you could give us more details on the software used to demultiplex the transport stream, as well as the software H.264 decoder you used for this demonstration? I’d also like to know how the DVB-S2 signal was fed into the PC in the first place. Were you using some kind of PCI DVB-S2 card?

    I realize that none of this software and hardware is available to us commoners, but I’d like to know the specifics nonetheless, assuming you are free to disclose such information.

    Cheers.
     
  11. Howard Pitfield

    Howard Pitfield
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    yes please - it's all knicker wetting stuff! Would love to hear more fromtechies behind the scenes....

    H :hiya:
     
  12. sgauntlett

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    The H.264 software encoder was from Moonlight and the demux and decoder was a filtergraph, again using Moonlight directshow filters. These filters were still being modified so may not be the same as are currently available for downloading.

    We did some tests using DVB-S PCI cards which worked but unfortunately there were no DVB-S2 cards available. We had to use a DVB-S2 demodulator with ASI transport stream out, then use ASI PCI input cards for get the data into the PCs for decoding. (sorry if that's too technical)
     
  13. Chris Muriel

    Chris Muriel
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    Thanks for letting us know how you were able to do it, SG.
    This explains why I couldn't get a sensible result with the equipment that I have and my own H264 s/ware solutions.

    DVB-S2 cards aren't available yet but I have been watching various announcements from IC manufacturers who will be supporting it.
    I bet that demodulator was quite expensive.
    As for ASI cards , they too are normally somewhat pricey.
    I know several fellow sat enthusiasts in the USA who do use ASI though (am a member/European correspondent of the USA MPEG2/DVB satforums and just returned from 2 weeks in the US).
    Incidentally TSReader does support ASI cards.

    Chris Muriel, Manchester.
     

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