Frame rate detection error?

Hi folks,

I think I'm having a frame rate detection error in the transcoding phase.

I have a TV show in a DVD, recorded in some DVR device. dvdrip
detected a 29.97 frame rate (I'm in Brazil, whe use Pal-M as the TV
system) - and I think it is right (have no idea how to check this
directly from the .vob file).

But when I transcode the ripped title, the audio runs great but the
video is always slower than the original - doing some rough math, it
appeared that he was encoding a 29.97 fps into a 23.976 fps movie. But
mplayer was telling me that the encoded movie had a 29.97 fps.

Inspecting my logs, I did the transcode part by hand playing around
with the parameters and notice that the parameter -f was causing my
headache.

dvdrip gives me the following ouput in the logs:
[...] transcode -H 10 -a 0 -x vob -i
\/windows\/g\/dvdrip\/vol6\/vob\/001\/ -w 273,50 -c 1-2000 -L 0 -A -N
0x2000 -f 30,4 -M 2 -Y 8,8,8,8 -B 12,26,8 -y xvid -o
/windows/g/dvdrip/vol6/avi/001/vol6-001.avi --print_status 25 [...]
(begining and ending removed for clarity)


Changing from "-f 30,4" to "-f 29.97" solved my audio/video sync
problems at all.

The transcode manpage is not clear at all, and made things even more
obscure to me. Can someone help me solve this problem?

And how could a 29.97 fps vob be converted to a 29.97 fps avi and
became a 'slow motion' version? It is really strange to me.


If you need more information, please ask anything - as a beginner, I
don't know what else will be useful here...



Thanks in advance,
Marcos