[FFmpeg-user] Framerate Question

[Andrey Utkin]

2012/3/5 Jared McIntyre <jmcintyre at dfsoftware.com>:
> I'm re-encodeing broadcast video. The source was apparently 720 30fps, but is being broadcast 60fps where every frame appears twice. I thought I'd try to save some space by re-encoding and using 30fps to cut out every other frame. I used the following command:

I believe x264 encoder is able to compress efficiently in this case,
without such a hack.

> ffmpeg -i in.mpg -acodec libfaac -ab 160k -crf 23.1 -vcodec libx264 -tune animation -preset faster -profile baseline -f mp4 -r 29.97 out.mp4
>
> I was a bit surprised to find out that if I used -r 29.97 I would get a file with half the frames, but a larger size than if I hadn't done so. I'm sure I'm misunderstanding something, but is this the expected behavior? Here is the log data in case about the encodeing:

What's the intention of -tune animation flag?
To get video of desired bitrate, give that bitrate as a parameter.

I'd suggest to not change framerate, and just tune encoder options to
have satisfying output size or quality.
Start from simply transcoding it without any options, just setting
desired bitrate.

-- 
Andrey Utkin