[Ffmpeg-devel] frame accept question

Martin Boehme boehme
Thu Oct 6 18:09:11 CEST 2005

Bram Biesbrouck wrote:
> I used the output_example.c file as a framework for my program. In a loop of 
> (say) 50 iterations, I feed the encoder 50 screenshots (encoder-framerate=25 
> fps, images are 1024x710 px, depth 24 and 32 bpp). I timed the generation of 
> one image and it takes the generator about 10 ms, so that leaves 30 ms for 
> the encoder to encode the frame (right?) at a correct framerate.
> When I run the program, the loop (image-generation + encoding) takes about 2.5 
> sec and the video plays back too fast (because of frame dropping I suppose). 
> I tried to look up the length of the video but I couldn't find out how 
> (mplayer says it's 0:00). I guess it's around 2 sec, but in theory it should 
> be less, I think, because of the frame dropping.
> I don't really have a specific question, but can someone explain to me what's 
> happening in this encoding-process?

It simply sounds as if encoding is taking too long... for the resolution 
of video that you're encoding, that sounds plausible. That also explains 
why the video is playing too fast... 2.5 seconds worth of video is being 
played in 2 seconds.

The easiest solution to this is of course to just reduce the 
framerate... to maybe 15 fps.


Martin B?hme
Inst. f. Neuro- and Bioinformatics
Ratzeburger Allee 160, D-23538 Luebeck
Phone: +49 451 500 5514
Fax:   +49 451 500 5502
boehme at inb.uni-luebeck.de

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