[FFmpeg-user] fps in March 13 git: -r 29.97 = 2997 tbn ???

[Baptiste Coudurier]

Hi,

On 04/02/2011 04:50 AM, Mike Scheutzow wrote:
> sean darcy wrote:
>> Converting to an android playable file, I can't seem to set the fps.
>> The input is 29.97. I tried setting -r to 29.97:
>>
>> ...
>>
>> Output #0, ipod, to 'OUTPUT1.m4v':
>>   Metadata:
>>     encoder         : Lavf52.102.0
>>     Stream #0.0: Video: libx264, yuv420p, 720x480 [PAR 8:9 DAR 4:3],
>> q=0-69, pass 1, 10000 kb/s, 30k tbn, 29.97 tbc
>>
>> tbn is the framerate for the AVStream of the container, as I gather
>> from google. It seems that -r affects tbn of the output. But really
>> oddly.
>>
>> How do I set fps of the output?
>>
> 
> You misunderstand the meaning of tbn. tbn is not the "framerate" of the
> container, it is the timebase.
> 
> A timebase is like a clock, and indicates ticks per second. Generally,
> higher values are better.
> 
> Both values of tbn you saw should work fine for your file. You got
> different values because 29.97 is not *exactly* equal to 30000/1001.
> 
> Also, be careful believing the tbn / tbc "Output #0" stats - they have
> been broken for months. Use 'ffmpeg -i infile' to get accurate values.

No, the values are correct and accurate, you can trust them.

-- 
Baptiste COUDURIER
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