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  The Return of the Blue Q
Subject:   Having trouble with frame grabbing (code from another article)
Date:   2004-07-21 09:02:10
From:   johnmangum

I was trying out the code grabbing a frame from a movie in your article here.


But I'm having trouble getting a good jpeg file from a movie. Here's the code:

QTFile qtFile = new QTFile("/Users/josh/kelley20.mp4");

OpenMovieFile movieFile = OpenMovieFile.asRead(qtFile);
Movie movie = Movie.fromFile(movieFile);
int j = 0;
int step = (movie.getDuration() - movie.getTime())/5;
for (int i = movie.getTime(); i < movie.getDuration(); i += step) {
Pict pict = movie.getPict(i); // frame number
File f = new File("/Users/josh/quicktime/test" + j +".jpeg");


It almost works. There is a file saved and I can open it in safari and it's the right picture. Unfortunately it won't open in camino ("this jpeg contains errors") or preview. It's not really a jpeg though. Graphics Converter says its file format is "QuickTime Importer (QuickDraw)".

Any idea how i can convert this into a jpeg? I've tried using GraphicsImporter,on the file like this:

GraphicsImporter gi = new GraphicsImporter(qtFile); // get a cantFindHandler error here
GraphicsImporterDrawer myDrawer = new GraphicsImporterDrawer
QTImageProducer qtProducer = new QTImageProducer (myDrawer,
Image image = Toolkit.getDefaultToolkit().createImage(qtProducer);

but I get the "Unsupported on Mac OS X and Java 1.4 and higher" error on the GraphicsImporterDrawer line. I'm using 10.2, could that be a problem? (I think i've updated quicktime java properly).

Could i use ibm's toolkit for this?

Thanks for your help and great articles, J.

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  • Chris Adamson photo Having trouble with frame grabbing (code from another article)
    2004-07-22 10:27:30  Chris Adamson | O'Reilly AuthorO'Reilly Blogger [View]

    This is coming in a soon-to-be-announced QTJ book from O'Reilly (pause for effect of thundering applause), which I'm just now able to talk about. I'm trying to get the example code posted on an open-source site (probably java.net) ASAP.

    Anyways, I did the QuickDraw chapter a few weeks ago. What you've done is shockingly close to something in the book.

    Two catches:

    • you don't need to write the Picts to disk. Copy a Pict's bytes to a buffer that's 512 bytes larger, so you have a 512-byte header pad. Point the GraphicsImporter to that memory with setDataReference().
    • there are two GraphicsImporterDrawers. You seem to be picking up the deprecated one from quicktime.app.image (all of which is gone). Check your imports to make sure you're getting the new one from quicktime.app.view.

    --Chris (invalidname)