[Ffmpeg-devel] [Bug] m2p -> mpg hangs on audio

[Matthijs Douze]

Hi

On a x86-64 linux box, I am trying to transcode a mpeg 2 video to mpg with

---------------------> snip

cpl_x64 $ ./ffmpeg_g -i ../begin.m2p -y -ar 32000  o.mpg
FFmpeg version SVN-r7868, Copyright (c) 2000-2006 Fabrice Bellard, et al.
   configuration: 
--prefix=/scratch2/cornwall/douze/compil/ffmpeg/cpl_x64/installed
   libavutil version: 49.3.0
   libavcodec version: 51.32.0
   libavformat version: 51.8.0
   built on Feb  7 2007 12:39:35, gcc: 4.1.1 20060724 (prerelease) 
(4.1.1-3mdk)
Input #0, mpeg, from '../begin.m2p':
   Duration: 00:00:00.8, start: 0.294367, bitrate: 9986 kb/s
   Stream #0.0[0x1e0]: Video: mpeg2video, yuv420p, 720x576, 6000 kb/s, 
25.00 fps(r)
   Stream #0.1[0xa0]: Audio: pcm_s16be, 48000 Hz, stereo, 1536 kb/s
Output #0, mpeg, to 'o.mpg':
   Stream #0.0: Video: mpeg1video, yuv420p, 720x576, q=2-31, 200 kb/s, 
25.00 fps(c)
   Stream #0.1: Audio: mp2, 32000 Hz, stereo, 64 kb/s
Stream mapping:
   Stream #0.0 -> #0.0
   Stream #0.1 -> #0.1
Press [q] to stop encoding

<------------------ snap

It hangs. Specifying -an works. Removing -ar hangs. It hangs also on 
32-bit boxes (where I also get "Compiler did not align stack variables." 
messages, as both gcc 3.4.1 and 3.4.3 seem to ignore __attribute__ 
((aligned (16)), but this is another problem).

With gdb:

---------------------> snip

(gdb) bt
#0  pcm_decode_frame (avctx=0xa123c0, data=0x2b7cc38ad010,
     data_size=0x7fffe7b3749c, buf=0xa11f8a "", buf_size=1)
     at /scratch2/cornwall/douze/compil/ffmpeg/libavcodec/pcm.c:404
#1  0x000000000046cb62 in avcodec_decode_audio2 (avctx=0xa123c0, 
samples=Variable "samples" is not available.
)
     at /scratch2/cornwall/douze/compil/ffmpeg/libavcodec/utils.c:945
#2  0x0000000000414445 in output_packet (ist=0x9fcc50, ist_index=1,
     ost_table=0x9fe810, nb_ostreams=2, pkt=0x7fffe7b37600)
     at /scratch2/cornwall/douze/compil/ffmpeg/ffmpeg.c:1072
#3  0x0000000000417b39 in av_encode (output_files=0x987dc0, 
nb_output_files=1,
     input_files=0x987c80, nb_input_files=1, stream_maps=0x987e60,
     nb_stream_maps=0) at 
/scratch2/cornwall/douze/compil/ffmpeg/ffmpeg.c:1941
#4  0x000000000041d014 in main (argc=7, argv=0x7fffe7b37c58)
     at /scratch2/cornwall/douze/compil/ffmpeg/ffmpeg.c:3936

<------------------ snap

pcm_decode_frame is called with

buf_size=1992
buf_size=1995
buf_size=1
buf_size=1
buf_size=1
...

it loops with this unusable buf_size. The example file is available here:

http://lear.inrialpes.fr/~douze/ffmpeg_bug/begin.m2p

Any idea ?

Thanks

Matthijs