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I am trying to encode several BMPs\JPEG into a movie file using:

ffmpeg -f image2 -i a%d.jpg output.mpg      

The thing is that I want the frame rate of the movie to be 10, and it seems to be 25 (as a default I guess). How can I tell it what framerate to use?

I am using Windows 7, 64-bit (DELL).

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up vote 1 down vote accepted

Please read the FFmpeg documentation. The framerate is specified with -r.

As an example for image-to-video conversion, they mention:

Use ffmpeg for creating a video from the images in the file sequence ‘img-001.jpeg’, ‘img-002.jpeg’, ..., assuming an input frame rate of 10 frames per second:

ffmpeg -i 'img-%03d.jpeg' -r 10 out.mkv

Note that normally, the usage of -f image2 isn't necessary. Also, the default settings used to convert to .mpg files may result in low quality. If you can afford it, try using x264 and MP4 container instead:

ffmpeg -i a%d.jpg -r 10 -c:v libx264 -preset slow -crf 21 output.mp4

Vary the -crf parameter for quality, where less means better quality and more means worse quality. Sane values could be anything from 18 to 26, with the default set at 23.

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Perhaps the documentation should be made more clear since by default images will have an input frame rate of 25. Adding -r 10 as an output option will cause ffmpeg to drop frames, but using it as an input option will use all frames. –  LordNeckbeard Oct 14 '12 at 18:06
    
Ah, interesting. So probably better specifying -r 10 -i … then for the above use case? –  slhck Oct 14 '12 at 18:21
    
For the OP's use case I think it would probably be best as an input option. Unfortunately, I doubt .mpg can support 10 fps (yet another reason for your MP4 recommendation). Different -r values can be used for input and output, but that will lead to dupes or drops which may be hardly noticeable or really ugly. –  LordNeckbeard Oct 14 '12 at 19:37
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