[MPlayer-users] 3:2 pulldown SVCDs play too fast
Steven M. Schultz
sms at 2BSD.COM
Tue Jan 1 20:37:39 CET 2002
Happy New Year!
> From: Arpi <arpi at thot.banki.hu>
> mplayer always care of these flags. if you done pulldown conversion, you
> have to remove these flags as well, otherwise you'll break the file.
> also set the fps field properly.
The movie was not "converted". I hesitated to use the word
"transcoded" since that means different things to different people
it seems. What I did was use 'mpeg2dec' (the 0.7 version available
from mjpeg.sourceforge.net) to decode the video, yuvscaler to scale
to SVCD size, and mpeg2enc to encode (with 3:2) to mpeg-2 again.
Are you familiar with the mjpegtools programs? Perhaps you can point
out what I am doing wrong in the following "transcoding" sequence:
cat vts_01_2.vob | mpeg2dec -s -o YUV | yuvscaler -O SVCD | \
mpeg2enc -n n -h -f 4 -q 8 -V 200 -p -o foo.m2v
mplex -V -f 4 -b 200 -O 242 -o foo.mpg foo.m2v foo.mp2
(the audio was already extracted in earlier steps). The "-p" option
to mpeg2enc says to generate the 3:2 pulldown flags and they are indeed
set in the output file.
The playback rate is of course 29.97 but the 'repeat first field'
flags are set.
It might be of interest that my portable DVD/SVCD player plays
the SVCD correctly. MPlayer plays back 20% fast on the video.
> mplayer handles 3:2 if the header says to do so.
> if the header is broken, only -fps 23.976 helps.
The header says "repeat first field" so it is a mystery why the
SVCD file plays back at 29.97 instead of 23.97.
I have been corresponding with the author of the mpeg2enc program and
he is looking at the timestamp info, etc. The suggestion was made
to me by him to ask if MPlayer has special case code for VOB files
and somehow overlooked the SVCD case.
Thanks for the (quick) reply - I'm hoping to start the year off by
solving this puzzling problem ;)
sms at 2bsd.com
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