[MPlayer-advusers] mencoder reads wrong frame rate flag from Quicktime files

[Dominic Bird]

-----Original Message-----
From: mplayer-advusers-bounces at mplayerhq.hu
[mailto:mplayer-advusers-bounces at mplayerhq.hu] On Behalf Of compn
Sent: 06 July 2010 21:17
To: mplayer-advusers at mplayerhq.hu
Subject: Re: [MPlayer-advusers] mencoder reads wrong frame rate flag
from Quicktime files

On Tue, 6 Jul 2010 17:13:56 +0100, Dominic Bird wrote:
>thanks for response! -demuxer lavf gives correct frame rate but cannot
>use lavf as im decoding prores so i need to use QTMLClient.dll for
>decoding. Mencoder version is r31372 win32 from

binary codecs dont work with lavf :(

>http://oss.netfarm.it/mplayer-win32.php. The file is not actually VFR,

are you able to use mplayer to play the video? here i only get
black screen. it does work in mencoder for me.

prores only works in windows xp for me. on win2k i get
DecompressSequenceFrameS result=0x-8961 and decoding fails. 8961 points
to 'noCodecErr' in the apple quicktime api. i'm not sure where to look
to fix this on win2k.

>but Final Cut flags it that way for some reason (as it seems to all
>captured HD files). Apparently the way you work out the frame rate is
>from the is like this...

argh, what an annoying fcp problem.

>It looks like ffmpeg's .MOV parser sets the video stream frame rate
>solely based on the time scale, which doesn't work for FCP's .MOV
>files. Instead it must divide the time scale by the duration of one
>video sample (as found in the 'stts' atom).
> 
>http://lists.mplayerhq.hu/pipermail/ffmpeg-devel/2006-February/006914.h
t
>ml
>
>Is there some way I can use the frame rate extracted by lavf and insert
>it in the command? Like -fps lavf? That would solve all my issues!!! If
>not then the -demuxer mov has a bug and needs to calculate the fps
>differently.

unfortunately no. you can only get lavf's fps information if you use
-demuxer lavf and that doesnt work with the binary codecs.

mplayer made -demuxer lavf default because -demuxer mov was
unmaintained. patches welcome to fix this fps bug , but i dont think
any of the devs are interested in fixing it.

this looks like the same bug in our bug tracker:
http://bugzilla.mplayerhq.hu/show_bug.cgi?id=1065

anyways, you can use the mplayer -demuxer lavf -identify -frames 1 to
get the correct fps, then script it to use that in your mencoder line.
it doesnt seem like a very efficient method, but at least it works.

-compn
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I agree with all your points but is there no way of getting a fix
submitted into the mov demuxer? Surely the way it works out the frame
rate just needs to be taken from the lavf demuxer. Its probably more
complicated than that but im not a coder undortunately!