Hello,
I'm using Cinelerra 2.1CV for a video, which includes many short inserts
from another video ("footage"). The latter video is pretty long (some 21
minutes).
The story (feel free to skip when you had enough)
=======
Initially, I transcoded the footage to MPEG-2 using mencoder, which
worked well, until I started to take pieces after its 8th minute of
footage. The A/V sync at that point was worse than 400 ms on the
rendered result. After trying to tweak anything possible, I reached the
(possibly wrong) conclusion, that the MPEG container should be blamed.
Yes, I tried doing mpeg3toc or letting Cinelerra do that automatically.
So I went for AVI.
Since MJPEG has worked well in the past (and MPEG-2 under AVI doesn't
seem to be supported by Cinelerra), I transcoded the footage to MJPEG,
which turned out to be a file slightly larger than 1 GB (as opposed to
MPEG-2's 808 MB). That file wasn't accepted by Cinelerra at all
(creating black image on rendering and messy image on Viewer).
OK, I said, let's try high-quality DIVX. Setting the parameters
carefully, I created a 159 MB DIVX file. The good news were that the A/V
sync problem was solved. This slowed down rendering, but who cares.
Also, I got error messages from Cinelerra every now and then and crashes
pretty often (which I usually don't experience). But the real killer was
some unexplained MPEG-style boxes appearing on the rendered video
(regardless of output format) every now and then.
It's important to note, that in all cases, mplayer played the transcoded
video with perfect A/V sync.
My question
=========
Has anyone had some success with taking small pieces from a long video
into a Cinelerra project *without* correcting the A/V sync manually?
More specifically, does anyone have a magic mencoder command, which will
turn any long video into something Cinelerra eats without problems of
the type I mentioned above?
Or are we all doomed to either chopping the footage to pieces or correct
the sync all the time?
Thanks in advance,
Eli
------------------------
Bonus: The mencoder commands I used for transcoding, using mencoder
1.0rc1-3.4.4:
To MPEG-2 (among other attempts)
mencoder - -oac lavc -ovc lavc -of mpeg -vf harddup -mpegopts format=dvd
-lavcopts
vcodec=mpeg2video:vstrict=1:vrc_buf_size=1835:vrc_maxrate=9800:vbitrate=5000:keyint=18:acodec=ac3:abitrate=192:aspect=4/3
-o "transcoded.mpg"
To MJPEG
mencoder - -oac mp3lame -ovc lavc -vf harddup -lameopts abr:q=5
-lavcopts vcodec=mjpeg -ffourcc MJPG -o "transcoded.avi"
To DIVX:
mencoder - -oac mp3lame -ovc lavc -vf harddup -ffourcc DIVX -lameopts
abr:q=5:br=224 -lavcopts
vcodec=mpeg4:mbd=2:trell:v4mv:last_pred=2:dia=-1:vmax_b_frames=2:vb_strategy=1:cmp=3:subcmp=3:precmp=0:vqcomp=0.6:turbo
-o "transcoded.avi"
--
Web: http://www.billauer.co.il
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