[MEncoder-users] A/V desync when joining two files

[luis jure]

[last night i sent this by mistake to the mplayer-users list, to which it
seems i'm not subscribed anymore... i hope it won't appear on both lists]


hello list,

i'm joining two avi files with the standard command:

mencoder -oac copy -ovc copy -o out.avi foo1.vi foo2.avi

both foo1.avi and foo2.avi have a correct A/V sync, but the output is
desynchronized after the point where the two files where joined.

i see the following when playing foo1.avi, right at the end:

a52: CRC check failed!  0.017 ct:  0.070 97491/97491  2%  0%  0.9% 0 0 
a52: error at resampling
A:4066.4 V:4066.4 A-V: -0.013 ct:  0.057 97498/97498  2%  0%  0.9% 0 0 
alsa-uninit: pcm closed

how can i possibly correct this and have a synchronized output when joining
the two files?

the output of "mplayer -identify foo1.avi" is:

MPlayer dev-CVS-060414-19:32-3.4.5 (C) 2000-2006 MPlayer Team
CPU: Advanced Micro Devices Athlon 64 Clawhammer; Athlon 64 X2 Toledo;
Turion Newark,Lancaster (Family: 15, Stepping: 10) CPUflags:  MMX: 1 MMX2:
1 3DNow: 1 3DNow2: 1 SSE: 1 SSE2: 1 Compiled for x86 CPU with extensions:
MMX MMX2 3DNow 3DNowEx SSE SSE2

91 audio & 208 video codecs
Playing foo1.avi
AVI file format detected.
ID_VIDEO_ID=0
ID_AUDIO_ID=1
VIDEO:  [DIV3]  640x272  24bpp  23.976 fps  976.1 kbps (119.2 kbyte/s)
Clip info:
 Software: transcode-1.0.2
 ID_CLIP_INFO_NAME0=Software
 ID_CLIP_INFO_VALUE0=transcode-1.0.2
 ID_CLIP_INFO_N=1
 File not found: '/home/lj/.mplayer/default.sub'
 Failed to open /home/lj/.mplayer/default.sub
 ==========================================================================
 Opening audio decoder: [liba52] AC3 decoding with liba52
 Using SSE optimized IMDCT transform
 AC3: 5.1 (3f+2r+lfe)  48000 Hz  448.0 kbit/s
 Using MMX optimized resampler
 AUDIO: 48000 Hz, 2 ch, s16le, 448.0 kbit/29.17% (ratio: 56000->192000)
 Selected audio codec: [a52] afm: liba52 (AC3-liba52)
 ==========================================================================
 ID_FILENAME=foo1.avi
 ID_DEMUXER=avi
 ID_VIDEO_FORMAT=DIV3
 ID_VIDEO_BITRATE=976088
 ID_VIDEO_WIDTH=640
 ID_VIDEO_HEIGHT=272
 ID_VIDEO_FPS=23.976
 ID_VIDEO_ASPECT=0.0000
 ID_AUDIO_CODEC=a52
 ID_AUDIO_FORMAT=8192
 ID_AUDIO_BITRATE=448000
 ID_AUDIO_RATE=48000
 ID_AUDIO_NCH=2
 ID_LENGTH=4066.48
 ==========================================================================
 Opening video decoder: [ffmpeg] FFmpeg's libavcodec codec family
 Selected video codec: [ffdivx] vfm: ffmpeg (FFmpeg DivX ;-) (MS MPEG-4 v3))
 ==========================================================================
 ID_VIDEO_CODEC=ffdivx
 alsa-init: using device default
 alsa: 48000 Hz/2 channels/4 bpf/65536 bytes buffer/Signed 16 bit Little
Endian
 AO: [alsa] 48000Hz 2ch s16le (2 bytes per sample)
 Starting playback...
 VDec: vo config request - 640 x 272 (preferred colorspace: Planar YV12)
 VDec: using Planar YV12 as output csp (no 0)
 Movie-Aspect is undefined - no prescaling applied.
 VO: [xv] 640x272 => 640x272 Planar YV12
a52: CRC check failed!  0.017 ct:  0.070 97491/97491  2%  0%  0.9% 0 0 
a52: error at resampling
A:4066.4 V:4066.4 A-V: -0.013 ct:  0.057 97498/97498  2%  0%  0.9% 0 0 
alsa-uninit: pcm closed
Exiting... (End of file)