[vdr] Xine plugins and LATM AAC audio (was Re: vdr 1.7.15 & eHD & French HD DTV)

Jonas Bardino jonas at bardinosen.dk
Wed Jun 23 10:40:35 CEST 2010


Bjørnar Nilsen wrote:
> Den 22.06.2010 07:21, skrev ECLiPSE:
>> I know that is not directly related to vdr, as my problem should come
>> from the reel src and not vdr.
>> I know there is here a good community of developpers and perhaps
>> someone can look at the src of the hdplayer and see if it could be
>> possible to add the detection of e-ac3 audio format , (and perhaps
>> finding the way to decode it or at least enable the ac3 compatibility?).
> 
> I have this problem on norwegian terrestrial channels, getting no audio.
> I have just upgraded to vdr-1.7.15(yavdr 0.2.0). Im using xineliboutput.
> Have used this ppa https://launchpad.net/~yavdr/+archive/unstable-vdr .
> 
> Here are the stats:
>     -Audio through xineliboutput doesnt work
>     -Audio through streamdev to vlc(windows 7) works.
>     -Recording plays fine in vlc(windows 7), but not wiht xineliboutput.
>     -Femon 1.7.7 does not detect this audio codec.
> 
> I have made a recording, here is a sample http://www.nilux.com/2.ts .
> 
> Dunno if its xineliboutput or vdr.
> 
> Regards
> Bjørnar Nilsen

Hi Bjørnar

(I changed the subject as I do not think it is directly related to the
original issue).

I'm no expert when it comes to the audio formats, but I have the same
experience here in Denmark. AFAICT the problem is missing LATM AAC[1]
decoding support in xine/ffmpeg/libfaad itself.
Neither xineliboutput or xine plugins provide audio for our MPEG4
channels, but I can connect mplayer or vlc to xineliboutput on port
37890 and get audio, so the core VDR components are not to blame. My
ffmpeg says something about missing LATM support when playing your
recording and my own:
$ ffmpeg -i 2.ts
FFmpeg version SVN-r23019-4:0.6~svn20100505-2yavdr1, Copyright (c)
2000-2010 the FFmpeg developers
  built on Jun 14 2010 12:58:34 with gcc 4.4.3
  configuration: --extra-version='4:0.6~svn20100505-2yavdr1'
--prefix=/usr --enable-avfilter --enable-avfilter-lavf --enable-vdpau
--enable-bzlib --enable-libgsm --enable-libschroedinger
--enable-libspeex --enable-libtheora --enable-libvorbis
--enable-pthreads --enable-zlib --disable-stripping
--enable-runtime-cpudetect --enable-gpl --enable-postproc
--enable-x11grab --enable-libdc1394 --enable-shared --disable-static
  libavutil     50.15. 0 / 50.15. 0
  libavcodec    52.66. 0 / 52.66. 0
  libavformat   52.62. 0 / 52.62. 0
  libavdevice   52. 2. 0 / 52. 2. 0
  libavfilter    1.19. 0 /  1.19. 0
  libswscale     0.10. 0 /  0.10. 0
  libpostproc   51. 2. 0 / 51. 2. 0
[mpegts @ 0x14a7420]AAC LATM not currently supported, patch welcome
[h264 @ 0x14abae0]number of reference frames exceeds max (probably
corrupt input), discarding one
    Last message repeated 361 times
[mpegts @ 0x14a7420]max_analyze_duration reached
Input #0, mpegts, from '2.ts':
  Duration: 00:00:22.22, start: 14142.519600, bitrate: 7256 kb/s
  Program 132
    Stream #0.0[0x200]: Video: h264, yuv420p, 1280x720 [PAR 1:1 DAR
16:9], 50 fps, 50 tbr, 90k tbn, 100 tbc
    Stream #0.1[0x280](nor): Data: 0x0011
    Stream #0.2[0x258](nor): Subtitle: dvbsub
    Stream #0.3[0x259](nor): Subtitle: dvbsub
    Stream #0.4[0x240]: Data: 0x0006

If you run xine --verbose=2 on the recording or on the xineliboutput
stream you will similarly see libfaad errors from the failed audio decoding.

I have experimented with a Personal Package Archive at Launchpad[2] to
do some further testing but my conclusion so far is that no combination
of recent ffmpeg and xine versions support LATM. Other players like vlc,
xbmc, mythtv and mplayer apparently include their own LATM
parser/decoder before handing of the decoding of the raw AAC stream to
libfaad.

I also commented on the issue at the VDR portal[3], but with no solution
so far.
I anyone knows more about this issue I'm all ears!

Cheers, Jonas

[1] http://wiki.multimedia.cx/index.php?title=Understanding_AAC
[2] https://launchpad.net/~jonas-bardino
[3] http://www.vdr-portal.de/board/thread.php?postid=912115



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