No audio in VLC, plays just fine in mplayer

About encoding, codec settings, muxers and filter usage
ph0t0n
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No audio in VLC, plays just fine in mplayer

Postby ph0t0n » 11 Apr 2008 11:38

Referring to my earlier post 'Transcoding from MPEG4/AAC to Theora/Vorbis'
at viewtopic.php?f=4&t=45705 ...

Why does VLC not recognize audio from the output file of the following script, while mplayer can play both audio and video just fine?
Quicktime also fails to play audio, but like VLC reports embedded audio to be AAC mono (from iSight).

./vlc -vvv --access live555 --codec faad --sout-transcode-channels 1 --sout file/mp4:lab_out.mp4 rtsp://localhost:554/lab.sdp

Adding the following flags makes no difference:

--audio-track 1 --audio-track 1 --audiofile-format s16 --audiofile-channels 1 --sout-transcode-channels 1

*** grep of warnings (no errors given) from VLC output below ***

[00000307] mux_mp4 private warning: i_length <= 0
[00000303] main input warning: clock gap, unexpected stream discontinuity
[00000303] main input warning: feeding synchro with a new reference point trying to recover from clock gap
[00000307] mux_mp4 private warning: i_length <= 0
[00000307] mux_mp4 private warning: i_length <= 0
[00000307] main private warning: no more input streams for this mux

*** Partial mplayer output below ***

MPlayer dev-CVS-051126-18:35-3.3 (C) 2000-2005 MPlayer Team
Mac OSX static build for ffmpegX
AltiVec found
CPU: PowerPC

Playing Movies/lab_out.mp4.
Quicktime/MOV file format detected.
--------------
MOV track #0: 412 chunks, 716 samples
Audio bits: 16 chans: 1 rate: 44100
MOV: Found MPEG4 audio Elementary Stream Descriptor atom (40)!
Fourcc: a4pm
--------------
MOV track #1: 413 chunks, 416 samples
MOV: Found MPEG4 movie Elementary Stream Descriptor atom (70)!
Image size: 320 x 240 (24 bpp)
Display size: 320 x 240
Fourcc: v4pm Codec: ''
--------------
MOV: longest streams: A: #0 (716 samples) V: #1 (416 samples)
VIDEO: [mp4v] 320x240 24bpp inf fps 0.0 kbps ( 0.0 kbyte/s)
==========================================================================
Opening audio decoder: [faad] AAC (MPEG2/4 Advanced Audio Coding)
AUDIO: 44100 Hz, 2 ch, s16be, 62.6 kbit/4.44% (ratio: 7825->176400)
Selected audio codec: [faad] afm: faad (FAAD AAC (MPEG-2/MPEG-4 Audio) decoder)
==========================================================================
==========================================================================
Opening video decoder: [ffmpeg] FFmpeg's libavcodec codec family
Selected video codec: [ffodivx] vfm: ffmpeg (FFmpeg MPEG-4)
==========================================================================
Building audio filter chain for 44100Hz/2ch/s16be -> 0Hz/0ch/s8...
AO: [macosx] 44100Hz 2ch s16be (2 bytes per sample)
Building audio filter chain for 44100Hz/2ch/s16be -> 44100Hz/2ch/s16be...
Starting playback...
VDec: vo config request - 320 x 240 (preferred colorspace: Planar YV12)
VDec: using Planar YV12 as output csp (no 0)
Movie-Aspect is 1.33:1 - prescaling to correct movie aspect.
VO: [quartz] 320x240 => 320x240 Planar YV12
[mpeg4 @ 0x6d311c]warning: first frame is no keyframe
A: 0.1 V: 0.0 A-V: 0.116 ct: 0.000 1/ 1 ??% ??% ??,?% 0 0
A: 0.1 V: 0.0 A-V: 0.139 ct: 0.000 2/ 2 ??% ??% ??,?% 0 0

etc. ...

Anybody?

Jean-Baptiste Kempf
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Re: No audio in VLC, plays just fine in mplayer

Postby Jean-Baptiste Kempf » 12 Apr 2008 09:13

samples somewhere?
VLC version?
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ph0t0n
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Re: No audio in VLC, plays just fine in mplayer

Postby ph0t0n » 12 Apr 2008 14:19

VLC version is 0.8.6f, running on Mac OS X 10.4.11 (mentioned only in original post, sorry).
More info about this and other problems regarding the project can be found there, at:

viewtopic.php?f=4&t=45705

You can find a copy of the DSS hosted source .mp4 file as a regular http download here:
http://www.ia-stud.hiof.no/~ingeteid/files/lab.mp4

(I have no running DSS server outside the school LAN and no admin access to set up port redirection to replicate the RTSP feed)

A partial sample (no transcoding, just .mp4 over RTSP to .mp4 file) with audio in mplayer only (though audio *is* reported in VLC and QT):
http://www.ia-stud.hiof.no/~ingeteid/files/lab_out.mp4

A full -vvv log of the RTSP-to-file operation can be found here (Unicode UTF-8, Unix line endings):
http://www.ia-stud.hiof.no/~ingeteid/files/log.txt

The sdp information received when calling the playlist item(rtsp://localhost:554/lab.mp4):
http://www.ia-stud.hiof.no/~ingeteid/files/mp4.txt

The sdp information received when calling the playlist itself (rtsp://localhost:554/lab.sdp):
http://www.ia-stud.hiof.no/~ingeteid/files/sdp.txt

A fully functioning ogg sample resulting from local file-to-file conversion can be found here:
http://www.ia-stud.hiof.no/~ingeteid/files/working.ogg

The intended final destination of the ogg file is an Icecast2 server.

Thank you very much for taking the time to look into this! :-)

*** UPDATE 16.04.2008 ***

When looking closer at the file in QuickTime Player using Window > 'Show Movie Properties' (cmd+J on Mac), it appeared that the embedded audio part was tagged with a START time LATER than the actual clip END time. No wonder it did not play. However, mplayer still did, and in sync, too. I guess QuickTime Player must misinterpret data in some fashion.


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