[MEncoder-users] wmv -> mpeg A-V Sync Loss/Jump

H.Edeler h.edeler at online.de
Sun Aug 27 19:12:42 CEST 2006

When converting some wmv to mpeg (for DVD) I run into A-V Sync problems. 

There is a little fault in the wmv. The wmv is playing with mplayer without sync
problems. At appr. 40sec there is something lost - a gap in the vid (maybe some
0,5sec) (not really a gap, it plays continousily, but you feel, there is
something lost). From there on it still plays in A-V sync to the end.

The mpeg is in A-V sync first. From the very moment, the wmv has its fault, the
mpeg is out of sync. The video may be 0,5sec leading to the audio from there on.

Mencoder reports at 42,5sec a duplicate frame, which is shortly after the fault
in the wmv.

I played with -noskip, -mc=0, harddup without success.

How can I manage to get the mpeg in sync? 

I don't understand why audiostream is reported to be longer than videostream.

What is the function of the audio-preload option? 
I wonder if vid and audio in the wmv might be more than 0.4sec in distance due
to the fault. So I thougt about increasing the audio-preload buffer size to e.g.
1.5. Strange thing MEncoder reports 0.4s independing on any change.

NB See log herewith. This is only one example of A-V sync loss. I run into this
thing very often when converting wmv's to mpg. So I should be lucky if you can
give any suggestions. 



E:\WMV test>mencoder.exe test.wmv -ovc lavc -ofps 25.000 -of mpeg -mpegopts form
at=dvd -vf scale=720:576,harddup -lavcopts vcodec=mpeg2video:vrc_buf_size=1835:v
rc_maxrate=3000:vbitrate=2000:keyint=15:acodec=ac3:abitrate=96:aspect=4/3 -oac l
avc -srate 48000 -af lavcresample=48000 -af resample=48000:1:0 -o test.mpg
MEncoder dev-CVS--3.4.5 (C) 2000-2006 MPlayer Team
CPU: Advanced Micro Devices Duron/Athlon 4/MP/XP Palomino (Family: 6, Stepping:
CPUflags: Type: 6 MMX: 1 MMX2: 1 3DNow: 1 3DNow2: 1 SSE: 0 SSE2: 0
Compiled with runtime CPU detection.
success: format: 0  data: 0x0 - 0x95b1c7
ASF file format detected.
VIDEO:  [WMV3]  720x576  24bpp  1000.000 fps    0.0 kbps ( 0.0 kbyte/s)
[V] filefmt:6  fourcc:0x33564D57  size:720x576  fps:1000.00  ftime:=0.0010
Opening audio decoder: [ffmpeg] FFmpeg/libavcodec audio decoders
AUDIO: 44100 Hz, 2 ch, s16le, 96.0 kbit/6.81% (ratio: 12005->176400)
Selected audio codec: [ffwmav2] afm: ffmpeg (DivX audio v2 (FFmpeg))
PACKET SIZE: 2048 bytes, deltascr: 43885
Opening video filter: [expand osd=1]
Expand: -1 x -1, -1 ; -1, osd: 1, aspect: 0.000000, round: 1
Opening video filter: [harddup]
Opening video filter: [scale w=720 h=576]
Opening video decoder: [dmo] DMO video codecs
DMO dll supports VO Optimizations 0 1
DMO dll might use previous sample when requested
GetOutput r=0x0   size:1244160  align:1
StreamCount r=0x0  1  1
Decoder supports the following formats: YV12 YUY2 UYVY YVYU RGB8 RGB555 RGB565 R
GB24 RGB32
Decoder is capable of YUV output (flags 0x1b)
VDec: vo config request - 720 x 576 (preferred colorspace: Packed YUY2)
VDec: using Planar YV12 as output csp (no 0)
Movie-Aspect is undefined - no prescaling applied.
SwScaler: using unscaled Planar YV12 -> Planar YV12 special converter
videocodec: libavcodec (720x576 fourcc=3267706d [mpg2])
Selected video codec: [wmv9dmo] vfm: dmo (Windows Media Video 9 DMO)
Limiting audio preload to 0.4s
Increasing audio density to 4
Writing header...
INITV: 0.200, 0.160, fps: 25.000
Pos:   0.8s     21f ( 2%)  0.00fps Trem:   0min   7mb  A-V:0.080 [0:96]
Skipping frame!
Pos:   1.2s     32f ( 2%)  0.00fps Trem:   0min  12mb  A-V:0.083 [2066:96]
Skipping frame!
Pos:   1.7s     44f ( 3%) 36.79fps Trem:   0min   9mb  A-V:0.082 [1857:96]
Skipping frame!
Pos:   2.5s     65f ( 4%) 35.40fps Trem:   0min  12mb  A-V:0.081 [1802:96]
Skipping frame!
Pos:   7.6s    194f (12%) 33.26fps Trem:   0min  13mb  A-V:0.083 [1720:96]
Skipping frame!
Pos:  42.5s   1067f (66%) 32.59fps Trem:   0min  15mb  A-V:-0.082 [1942:96]
1 duplicate frame(s)!
[mpeg2video @ 009DCCD8]Warning: AVFrame.pts=? trying to guess (1063)
Pos:  64.6s   1619f (100%) 32.64fps Trem:   0min  16mb  A-V:-0.082 [1969:95]
1 duplicate frame(s)!
[mpeg2video @ 009DCCD8]Warning: AVFrame.pts=? trying to guess (1616)
Pos:  64.7s   1621f (100%) 32.63fps Trem:   0min  16mb  A-V:-0.050 [1968:96]
Flushing video frames
Writing index...

Overhead: 3.199% (71741776503252796 / 128071251872120864)
Writing header...

Video stream: 1968.542 kbit/s  (246067 B/s)  size: 15925508 bytes  64.720 secs
1621 frames

Audio stream:   96.000 kbit/s  (11999 B/s)  size: 781824 bytes  65.152 secs

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