[MEncoder-users] audio slew when enocding from TVtuner

SZABO Zsolt szazs at mm.bme.hu
Mon Mar 13 23:19:46 CET 2006


I have tried to encode from a Pinnacle PCTV USB tuner with the following

mencoder -endpos $endpos -o name.avi tv:// \
-tv amode=0:input=1:norm=PAL:width=720:height=576:driver=v4l2:\
-ovc lavc -lavcopts vcodec=mpeg4:vbitrate=1200 -vf pp=lb -ffourcc XVID \
-oac lavc -lavcopts acodec=mp2:abitrate=192

However, I have found that the audio volume (from snd_usb_audio driver)
is too low (dumping it to wav, sox -e stat suggested 5.xx volume

Then I have tried -af volnorm, and -vf crop=688:560:16:8,pp=lb and at
the end of a 6000 sec recording there was a 10 second desynch between
the audio and video stream. :-(

Then I tried to omit outfmt=...,  lower abitrate, omit -af volnorm,
crop=... and autoaspect, and test it with ~600 sec. recordings. But the
experienced desynch. has remained.

Now, finally, I omit -vf pp=lb, though it is a 25fps composit input and
formerly I obtained interlaced (striped) avi. However, now, it seems good:

mencoder -endpos $endpos -o name.avi tv:// \
-tv amode=0:input=1:norm=PAL:width=720:height=576:driver=v4l2:\
-ovc lavc -lavcopts vcodec=mpeg4:vbitrate=1200:autoaspect\
-vf crop=688:560:16:8 -ffourcc XVID\
-oac lavc -lavcopts acodec=mp2:abitrate=192 -af volnorm

Is it possible? What can cause the mentioned slew between A-V?

PS: the version of the first mencoder is not sure, but the version used
in the latest tests was: MEncoder dev-CVS-060307-23:29-3.3.5

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