[FFmpeg-user] Issues with framerate read for wmv2 file

[Carl Eugen Hoyos]

2016-11-04 15:27 GMT+01:00 Mark Huang <mmhmmh at gmail.com>:
> Hi Carl,
>
> Thanks for answering my question. I tried using a forced frame rate using
> option "-r 30" and it seems to fix the issue. Out of curiosity, ffmpeg
> outputs the framerate as:
>
>     Stream #0:1(eng): Video: wmv2 (WMV2 / 0x32564D57), yuv420p, 640x480,
>> 800 kb/s, SAR 1:1 DAR 4:3, 1k tbr, 1k tbn, 1k tbc
>
>
> I assume that means 1000 fps?

No, it means the timebase of the video stream is 1/1000, asf files do
not specify a framerate.

> Is it that for the variable framerate wmv2 case ffmpeg doesn't use that
> field for doing the forced framerate conversion?

I don't understand the question.

If your question was "Why does it work for asf and mkv output but
not mov?", the answer is that FFmpeg's mov muxer does not support
variable frame rate and therefore the input file's framerate has to
be used, in absence the timebase (which indicates the maximum
framerate).

> Also I am not familiar with the asf container/format, is that the
> technical term for wmv2?

There is a video codec / video format "wmv2" and a marketing name -
among others - of "wmv" for the "asf" format.

Carl Eugen