[MPlayer-users] Transcoding 18 fps mpeg4 to VCD-compliant mpeg

Heimdall Midgard heimdalle at gmail.com
Mon Nov 7 04:05:20 CET 2005


Is is it even possible to convert an 18 fps mpeg4 video to a
~23.97 or ~29.97 fps VCD-compliant mpeg stream *without*
losing audio-video sync?. As my system can't cope with
recording at a full 29.97 fps, I'm forced to record at 18
fps. Since the shows are mostly low-motion anime, I find the
resultant AVI files to be satisfactory.

This is the command I use to record my 18 fps TV capture (I
hope I prettified the line breaks correctly):

mencoder -tv \
driver=v4l2:device=/dev/video0:normid=1\
:chanlist=us-cable:width=352:height=240:fps=18\
:amode=1:forcechan=2:audiorate=48000:alsa:adevice=hw.0 \
-ovc lavc -oac lavc -lavcopts acodec=ac3:abitrate=96\
:vcodec=mpeg4:keyint=0:vqscale=1 \
-vf detc=dr=1,crop=336:224:8:8,pp=lb,denoise3d=8:6:12\
-ofps 18 -mc 1 -o tvcapture.avi -ffourcc DIVX \
tv://45 -endpos 35:00

This is the command I use to transcode the AVI to mpeg1
format:

mencoder -oac lavc -ovc lavc \
-lavcopts acodec=mp2:abitrate=224:vcodec=mpeg1video\
:vbitrate=1150000:vrc_buf_size=327 \
-of mpeg -mpegopts format=mpeg1 -noskip \
-vf scale=352:240,harddup -ofps 24000/1001 \
-o vcd.mpeg tvcapture.avi

The mpeg is recognized by VCDImager but when played back
there's a huge audio-video desync of several seconds. What
am I missing here?

--
Albert Einstein: Phantasie ist wichtiger als Wissen, denn Wissen ist begrenzt.




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