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

sean darcy seandarcy2 at gmail.com
Sat Apr 2 21:28:36 CEST 2011


On 04/02/2011 07:50 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.
>
> Mike Scheutzow

Maybe more accurate, but much more confusing:

Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'OUTPUT1.m4v':
   Metadata:
     major_brand     : M4V
     minor_version   : 512
     compatible_brands: isomiso2avc1
     creation_time   : 2011-04-02 03:00:26
     encoder         : Lavf52.102.0
   Duration: 00:05:44.34, start: 0.000000, bitrate: 9920 kb/s
     Stream #0.0(und): Video: h264 (High), yuv420p, 720x480 [PAR 8:9 DAR 
4:3], 9916 kb/s, 29.97 fps, 29.97 tbr, 30k tbn, 59.94 tbc

This is not interlaced, why 59.94? And tbn, whatever it is, is 30,000???

sean



More information about the ffmpeg-user mailing list