Fw: CodecCanScale-DirectX/Video codec

Subject: Fw: CodecCanScale-DirectX/Video codec
From: "Alex Telitsine" <email@hidden>
Date: Wed, 26 Sep 2001 19:41:38 -0700

----- Original Message -----
From: "Alex Telitsine" <email@hidden>
To: <email@hidden>
Sent: Monday, September 17, 2001 1:34 AM
Subject: CodecCanScale-DirectX/Video codec

Hi,
I'm trying to implement "custom SCALING" in QuickTime/Win32
Image Compressor component (x2 scaling).

It seems to be working with RGB32 color mode, but with YUV/DirectX,
QuickTime has following strange behavior:

During playback, when codec can keep up decoding speed everything
seems to be fine, QT sends address of "DirectX" surface to the
DrawBand and I can scale and output correct video. But during "seek"
operation, or playback speed problem (dropped frames), QuickTime
sends PixMap allocated in memory. In this case, all parameters in PixMap
(bounds, row bytes) seem to be OK, but memory block allocated
(baseAddr) is 2 times smaller. I can check it with IsValidWritePtr.
Second part of memory block is invalid. And even if I re-allocate the
memory block with NewPtr, QuickTime works, but updates only
"top part of picture". Scaling is x2 in both directions.
This problem doesn't occur with DirectX disabled, or in RGB32
PixelFormat. So far I've tested kYUVSPixelFormat and
k2vuyPixelFormat modes. Same problem occurs with "BandDecompress".
I could be wrong, but it seems like problem in QT/DirectX with
"CodecCanScale" memory allocation and output functions.

I wonder if QT engineers are reading this list.
Thank you in advance,
Alex Telitsine, Streambox Inc.
email@hidden

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