[Pd] Finding frame rate for video

Chuckk Hubbard badmuthahubbard at gmail.com
Mon May 15 23:26:18 CEST 2006

On 5/15/06, chris clepper <cgc at humboldtblvd.com> wrote:
> On 5/11/06, Chuckk Hubbard <badmuthahubbard at gmail.com> wrote:
> > Wanting to automate opening videos in GEM.  Is there any library with
> > a function to check a movie header for fps?
> This really varies by platform and API.  For example, Quicktime doesn't
> really have the concept of a frame per second in the container format.  That
> might sound odd, but it allows for frames of different lengths in the same
> container and multiple frame rate tracks of media to work alongside each
> other.
> Right now with QT we sort of guess at the framerate because it helps to open
> the movie file faster.  It is not a very accurate number though and I would
> not use it for controlling playback.  The 'auto' and 'rate' messages do
> allow for accurate control of playback based on any media of any framerate.

But the speed of "auto" depends on the "frame" message sent to gemwin.
I want to score films with Pure Data.  The only way it will line up
correctly is if the fps is correct.  As of now I have to open the file
in Quicktime or Media Player to check, and manually change it in Pd.

I also have to be able to send specific frame messages, because I'm
not going to start at the beginning of a 15 minute movie file every
time I want to check a passage.
I'm still working out exactly how it's going to work; the tempo
control in my patch is exponential and so a little strange to
calculate beforehand.


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