[MEncoder-users] Encoding iPhone MOV into MPEG-2 -- Video framerate is super fast!?

[Jarred Nicholls]

Hi everyone,

Firstly I appreciate you all taking the time to help with this issue.  Maybe
it will stand out as an obvious or simple solution to someone.

I am encoding a video taken from an iPhone 3GS (h.264 video, MOV container
at 90 degree rotation/transformation matrix in the tkhd header). I have had
troubles encoding this type of video into DVD compliant MPEG-2 video using
mencoder (no issues with ffmpeg), but for this type of video I need mencoder
strictly for the expand and rotate filters.  The resulting MPEG-2 video is
super fast (every 2 out of 5 frames are dropped/skipped when encoding) and
the audio after muxed with the video is at its original speed.  It's almost
like the frame rate is super fast (~50+ fps), but definitely has something
to do with the frames being dropped.  MediaInfo reports the average fps is
19 (the video is variable fps).

Here is the command I run:

mencoder -oac lavc -ovc lavc -of mpeg -mpegopts format=dvd:tsaf -vf
rotate=1,expand=720:480,harddup -srate 44100 -af lavcresample=44100
-lavcopts
vcodec=mpeg2video:vrc_buf_size=1835:vrc_maxrate=9800:vbitrate=5000:keyint=18:vstrict=0:acodec=ac3:abitrate=192:aspect=4/3
-ofps 30000/1001 -o test2.mpg IMG_0018.MOV

Here is a link to the source video and the result video respectively:

http://www.bcam.org/tmp/IMG_0018.MOV
http://www.bcam.org/tmp/test2.mpg

I have tried several alterations to the command above.  One in particular
was to simply remove the explicit -ofps setting to see if it would simply
keep the original video's framerate...and it errored out saying "MPEG1/2
does not support 617/12 fps" which is approximately 51.41fps.  This would
explain the skipped frames and the video speed up, but why is it reading
51.41fps when the original video is (on average) only 19fps?

Thanks for your help!!
Jarred Nicholls