[Ffmpeg-devel] Re: getting the frame-rate

IOhannes M Zmoelnig zmoelnig
Thu Sep 1 15:01:20 CEST 2005

Rich Felker wrote:
> All formats have a time base, which may or may not correspond to
> framerate. This is the most you can know.
>>what happens if there are formats that do not have a constant image-size 
>>any more ? will you remove the dimension-information from the API ?? 
> No. If it were a real issue, the image dimension information would be
> generalized in such a way as to _handle_ changing dimensions. (In such
> a stupid hypothetical situation...) Similarly this is what happened
> with framerate. The concept of framerate was generalized to time base
> in order to handle video without a framerate while still providing
> maximal information when there is a framerate.

thanks for the information.
i have changed my code accordingly and it works quite well now.
of course i haven't tested it with a video that does something unusual 
like having varying framerates (don't know where i can find such a video).

>>(mpeg4 provides arbitrary shapes. whether it also provides a means to 
>>change this shape in time, i dunno)
> This is nonsense that's outside the video part of mpeg4.

just for my information (since i am really a "dunno" in this case): is 
the nonsense on my side (e.g. i misunderstood the specs which i haven't 
read. like arbitrary shapes are allowed, but not in the video-part of 
the spec), or is it just that mpeg4 has nonsense in its specs (i assume 
the non-sense is on my side, but i'd like to be sure)

> Rich

a last question:
i (think that i) know that the ffmpeg-developers suggest using the CVS 
version of FFMPEG and that applications using FFMPEG should ship their 
code with the ffmpeg-version they are compiled with (or at least a 
version, which is known to provide the used API)

would it totally break the development work-flow if a minor 
version-number would be changed if the API of the library changes ?
or do i have to use the build-number for this ?

thanks anyhow


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