Re: software for manipulating AVI files

[Marius Schamschula]

This general issue has been plaguing Matlab for quite some time. Many  
years ago I used Matlab's QuickTime import and export functions. I  
upgraded Mac OS and QuickTime, Mathworks didn't fix things, so the  
functionality was broken.

Instead of going back to a 1995 system configuration, my solution was  
to work with image sequences for both I/O. I still do this under Matlab  
7.1 since I found that I had much more control over building the  
resulting movie.

FWIW: I use QuickTime Pro to split sequences and GraphicConverter to  
build them.

On the open source side ImageMagick has its own sequence file format  
but can be built with mpeg2 support. ImageMagick is used as the  
graphics file I/O engine for OpenDX.

On Sep 29, 2005, at 3:19 PM, Brendan Drew wrote:

> That, I'm afraid, I couldn't tell you. I try to stay away from canned  
> sequences on principle (this way it's much harder to optimize  
> algorithms to work only with one particular sequence, which makes it a  
> bit easier to design for good general performance)
>
> I vaguely recall something about using Windows BMPs as the frame data  
> with the header data stripped and not being able to use   colors > 236  
> in any channel, but don't quite me on that -- I may be confusing  
> uncompressed AVI with CinePak.
>
> John W. Eaton wrote:
>
> > On 29-Sep-2005, Brendan Drew wrote:
> >
> > | Unfortunately, the AVI file format is not quite as simple as one  
> > would | want to believe. AVI is merely a container format, it makes  
> > no | statements about how things are compressed or decompressed.  
> > Depending on | the codecs you're using, things can become very  
> > complicated very quickly | (specifying which codec and then specific  
> > parameters for that codec, | followed by relevant sanity checking,  
> > correctly matching AVI streams to | codecs when you have multiple  
> > versions to choose between, etc.)
> >
> > OK, I see that now.  I suppose my question displayed my ignorance of
> > the situation.  I assumed that "AVI file" was well defined.
> >
> > OK, so suppose we don't care about handling anything more than being
> > able to read and write the kinds of AVI files that Matlab produces?
> > Would that be hard to write?  I'm looking at
> >
> > http://msdn.microsoft.com/archive/default.asp?url=/archive/en-us/ 
> > directx9_c/directx/htm/avirifffilereference.asp
> >
> > Given this, I think I can write code that will decode the file I have
> > (generated with avifile and addframe with no compression).  So the
> > question I have now is, how is the frame data stored for this kind of
> > file?
> >
> > jwe
Marius
--
Marius Schamschula,  Alabama A & M University, Department of Physics

    The Center for Hydrology Soil Climatology and Remote Sensing
   http://optics.physics.aamu.edu/ - http://www.physics.aamu.edu/
          http://wx.aamu.edu/ - http://www.aamu.edu/hscars/



-------------------------------------------------------------
Octave is freely available under the terms of the GNU GPL.

Octave's home on the web:  http://www.octave.org
How to fund new projects:  http://www.octave.org/funding.html
Subscription information:  http://www.octave.org/archive.html
-------------------------------------------------------------