[Libav-user] I'll ask in other words - how can I force input frame rate?

wl2776 wl2776 at gmail.com
Mon Oct 10 09:32:28 CEST 2011

Steffen Ebersbach-2 wrote:
>> wl2776 wrote:
>> So, it is possible to force input frame rate. How can I do it in my
>> application?
> Hello,
> in an own application you have to do this resampling by your self. If 
> you have 2fps input and 25fps output, it means that you have to write 
> each picture from the input 12,5 times to the output. In fact this is 
> not possible, so you have to do 12 and 13 pictures for each second. The 
> code should look like this
> - read input sample
> while < 12 (13)
>      - write to the output
>      - wait 40ms
> .. and so on

Sorry for repeating quotes, one more thing, which probably is not obvious.
You can specify "-r" switch (set frame rate) in the command line of ffmpeg
*before* "-i" switch. 
This makes ffmpeg to consider that *incoming* frame rate is given from
outside and it should not neither determine nor assign a default value.

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