[FFmpeg-user] h264 timebase question

Stuart Bruce stuartrbruce at gmail.com
Wed Jan 1 21:05:23 CET 2014

On 31/12/2013 15:15, Carl Eugen Hoyos wrote:
> Stuart Bruce <stuartrbruce <at> gmail.com> writes:
>> time_base (which has become 1/12288 even though the source
>> is 1/24000),
> I believe you can set this with -video_track_timescale 24000
That's great, thank you for pointing that out. That works, and the 
resulting MOV has the correct time_base and also, as a result, the same 
duration_ts value as I expected.

Crucially, this seems to now mean that the thumbnail generation through 
seeking now appears to be frame-accurate, when it wasn't before. I need 
to test it thoroughly, but it looks like it's all sorted.

There's still one mystery, which is why the codec_time_base when 
exported from Media Composer is given as 1/48000 whereas the 
codec_time_base from an FFmpeg export is 1/48, but it doesn't seem to be 
affecting the results I'm getting so I'm happy to let that one just be a 
mystery if need be!

Thanks again


Stuart Bruce
stuart at stuartbruce.co.uk

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