Thank you for your response: it helps me a lot!
I had the solution right under my eyes but didn't saw it: instead of
saving one meta-data per image description extension (which must be
different to retrieve them in the codec), I save all of them in a big
array in the image description extension.
Et voila!
Regards
On Wed, 2006-09-06 at 19:41 +0300, George Birbilis wrote:
> > > > My problem is that I need to store additional data per-sample. My
> > > > first attempt was to use image description extensions to
> > store them
> > > > (one extension per-image-description) but I quickly noticed
> > > that the
> > > > image descriptions given in BeginBand() are always the same
> > > (only the
> > > > dataSize is changing). So I wrote and
> > > IsImageDescriptionEquivalent()
> > > > function for my codec which returns always false (since my
> > > extension
> > > > is always
> > > > different) but then, there is one codec instance created for each
> > > > frame!
> >
> > Search the list archive on this, there was a discussion on
> > storing per-frame custom data sometime ago, with Tim Monroe
> > replying with the way to do it I think. Let me know if you
> > can't find it to search my mail archives...
>
>
> I think the following discussion might help (I didn't remember well and
> thought Tim had replied to it). See the mention to
> AddImageDescriptionExtension and GetImageDescriptionExtension below. Please
> follow up here with confirmation in case it did the job (always useful for
> people searching list archives to know)
>
> Cheers,
> George
>
> -----------------------
>
>
> Hello Glenn,
>
> Thanks a lot for your suggestion.
> As a matter of fact, the format of the movie has already been changed so
> that our component can be called appropriately. To do that, I wrote a tool
> that converts the original movie (MPEG4 for example, and not necessarily a
> .mov file per se) into a new QuickTime movie in which each frame is "typed"
> as encoded with a proprietary codec, so I think there will be no objection
> if the tool adds the metadata in an image description extension. I will
> check that right now and modify my converter tool as needed if I'm allowed
> to do that.
> I'll let you know how it works.
>
> Thanks again!
>
> Olivier
>
>
> At 01:33 am + 1300 16/03/2006, Glenn Anderson wrote
> > At 11:48 am +0100 16/03/2006, Olivier wrote:
> >> Hello,
> >>
> >> I have a movie that contains some metadata that are needed to
> >> decode the frames. The proprietary metadata is unique but is
> >> needed for each frame. This metadata is in the movie file, *not*
> >> in the frames (it would not be efficient to repeat the same data
> >> in each frame, of course).
> >> I need to write a codec that decodes the movie frames, but I can't
> >> see a way to access the movie file from the codec to read the
> >> metadata. Is there any way to do that?
> >> Or should I write a media handler instead to access the movie
> >> metadata and from the media handler call the codec passing it the
> >> metadata that it needs? Or should I write a data handler? Or a
> >> combination of several components?
> >
> > Is it too late to change where the metadata has been put? If not,
> > put it in an image description extension instead. That way only one
> > copy of it will be stored in the movie, and it gets passed to your
> > codec. See the AddImageDescriptionExtension and
> > GetImageDescriptionExtension calls.
>
>
>
>
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