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Re: Saving in-memory movie

I dispaired I wasn't going an answer to this, but help arrived
as I was just putting the finishing touches on my workaround. Derek Bass was
kind enough to point out his posting which he sent a couple of weeks earlier.
His research discovered that a solution to my problem is to use a different
magic data handle in my calls to NewTrackMedia, which is probably the one to
prefer if you're creating
in-memory movies - and want to save them without flattening.

The fine print is in these postings:

Derrick Bass, "Re: Saving movies with handle data references", QuickTime API
List, Sep 4 2002.
<http://lists.apple.com/archives/quicktime-api/2002/Sep/03/savingmovieswithhandleda.txt>
(if the link splits paste the bits together)

which in turn refer to:

Chris Flick, "Re: Adding track without modifying original file", QuickTime API
List, Feb 15 2000.
<http://lists.apple.com/archives/quicktime-api/2000/Feb/15/addingtrackwithoutmodify.001.txt>

Apple Computer Inc., Technical Note TN1195, Tagging Handle Data References in
QuickTime 4, Apr 3 2000.
<http://developer.apple.com/technotes/tn/tn1195.html>

There is a gotcha in all this - this technique causes data to be stored in the
movie resource - one of the postings warns against using the technique for
storing large amounts of data e.g. pictures and sounds. I don't understand the
significance of this, or whether it is of concern when using data fork only
files, but bear in mind the result of saving an in-memory movie using this
technique will be different than creating your movie in a file in the first
place (without magical data handles to NewTrackMedia) and updating the movie
resource in that file.

Regards,

Andrew

Andrew Friedman wrote:
>
> Hello,
>
> I wonder if someone can help me out on this. It's easy...
>
> I'm creating an in-memory movie adding effects and volume tween twacks to
> tracks containing references to orginal media.
> (See Scott Kuechle's mail of March 21 2000 for how to create an
> "in-memory movie". Thanks Scott, and thanks to Brian for asking the question.)
>
> It plays ok in my app.
>
> If I save it to a new file, (CreateMovieFile followed by UpdateMovieResource)
> and view/play it in QT Pro. The structure appears correct, i.e. the effects and
> tweens are listed as video and tween tracks respectively and the effects are
> correctly listed in the move info track), but ... tweens cause QT Player to
> crash, transitions do not show up, and filters cause content not to display.
>
> I presume the effects and tween are not being copied completely from the
> in-memory movie. I presume they are being copied by reference from the
> in-memory movie which is consistent with the way it works when an external
> movie file is used instead of the in-memory movie.
>
> Should QT be smart enough to do a value copy in this case and what's the way
> around it?
>
> The simplest thing (for me, albeit with some minor design grottiness) seems to
> just build my movie into the destination file in the first place and then
> UpdateMovieResource.
>
> But I wondering what the correct method is:
>
> I assume FlattenMove would get around this, but I don't want to copy the
> original media.
>
> I presume I could iterate through my in-memory movie making a copy of it being
> sure to value copy any tracks that reference media only existing in the
> in-memory movie, but that seems like too much effort to be right.
>
> This is on Windows, QT6, BTW, and the file is a data fork only one if its
> matters.
>
> Thanks,
>
> Andrew
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References: 
 >Saving in-memory movie (From: Andrew Friedman <email@hidden>)



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