[MPlayer-users] TV/video capture - 2 pass

Mike Holland myk at plug.linux.org.au
Fri Dec 6 05:10:02 CET 2002


To get better quality video capture, it seems logical to do 2 passes.
Compress to a reasonable size in realtime, and then do a second pass 
without realtime constraints.

  I tried the lavc/mpeg4 built-in 2-pass, but no luck. I'm assuming it
requires the original input for the second pass, so no good for video
capture?

  Whats the alternative? Is there a codec that gives less compression, but
better quality and lower CPU demand?  It would be good, but not essential,
if the intermediate format was playable. Then I can choose to watch, or
compress further for archiving.

ALSO: I have tried the lavc/mjpeg coder, but it doesnt produce the
requested bitrate,
 eg ask 1800, got [7023:63].  Tried vbitrate=9000 , got [5677:63]  No 
errors in log.

Does that codec not support vbitrate? The HTML docs show a similar
example.

Command line:  mencoder -tv
on:driver=v4l:width=768:height=576:device=/dev/video0:input=1:forcechan=2
-oac mp3lame -lameopts cbr:br=64:mode=3 -ovc lavc -lavcopts
vcodec=mjpeg:vbitrate=1800:keyint=100 -vop pp=lb,crop=752:562:4:2 -info
"..."

(Note: audio captured as stereo and converted to mono, due to limits of 
i810 sound driver.)

-- 
        The origin of Truth is Doubt - Socrates




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