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Re: reading 10 bit uncompressed 4:2:2 QuickTimes?

Andreas Wittenstein wrote: 
Paul,

How are you creating the 64-bit GWorld? 'QTNewGWorld()' with 'k64ARGBPixelFormat' works on both Mac and Windows.

Thanks Andreas! I was just using "64" instead of k64ARGBPixelFormat. Also, I was using NewGWorld instead of QTNewGWorld. Go figure.

How are you testing the bit depth? By convention, for all direct- color representations, regardless of the actual precision, the 'depth' field of the 'ImageDescription' is always set to 32 if there's alpha, 24 if there isn't. The 'cmpSize' field of the 'PixMap' will give you the

That is what I am discovering. I was using GetMediaSampleDescription to return that weird SampleDescriptiongHandle that needs to be casted to an ImageDescriptiongHandle. Not the best designed API I have seen. Regardless, as you mention, the "depth" field of that struct is lying, and reporting 24 bits.

correct component precision, but note that, by convention, the 'cmpCount' field of the 'PixMap' specifies the logical, not physical, number of components, and you may need to set it to 4 yourself if you want to see the alpha channel. To determine the actual precision of a pixel, use 'ICMGetPixelFormatInfo()' and look at the 'bitsPerPixel' field of the 'ICMPixelFormatInfo'.

Currently I am not using any of the ICM functions. Do you have any pointers to sample code on how to call ICMGetPixelFormatInfo?

Many thanks!

-Paul


Andreas Wittenstein
BitJazz Inc.
http://www.bitjazz.com/sheervideo/


On 16 Aug, 2005, at 06:25, Paul Miller wrote:

How is it possible to read QT movies compressed with 10 bit and 16 bit (PER CHANNEL) codecs?

I have working code to read QT movies uses 32-bit GWorlds (and GetMoviePict). I tried creating a 64-bit GWorld (on QT for Windows) and it failed.

I also have a 10 bit 4:2:2 uncompressed sample movie, and when I query its sample description (again using Apple sample code), I see the bit depth is 24 bits. It should at least be 30 bits, and I would expect to "render" it to RGB using a 64-bit GWorld.

Can someone help me make sense of this?

Many thanks!

--
Paul Miller | email@hidden | www.fxtech.com | Got Tivo?







--
Paul Miller | email@hidden | www.fxtech.com | Got Tivo?

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References: 
 >reading 10 bit uncompressed 4:2:2 QuickTimes? (From: Paul Miller <email@hidden>)
 >Re: reading 10 bit uncompressed 4:2:2 QuickTimes? (From: Andreas Wittenstein <email@hidden>)



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