SGSetCompressBuffer
Some video source data may contain unacceptable levels of visual noise or artifacts. One technique for removing this noise is to capture the image and then reduce it in size. During the size reduction process, the noise can be filtered out.The
SGSetCompressBufferfunction allows the sequence grabber component to direct your component to create a filter buffer for your video channel. Logically, this buffer sits between the source video buffer and the destination rectangle that the sequence grabber component sets with theSGSetChannelBoundsfunction, described on page 6-60. The filter buffer should be larger than the area enclosed by the destination rectangle.
pascal ComponentResult SGSetCompressBuffer (SGChannel c, short depth, const Rect *compressSize);
c- Identifies the channel connection for this operation.
depth- Specifies the pixel depth of the filter buffer. If the sequence grabber sets this parameter to 0, use the depth of the video buffer (which the sequence grabber sets with the
SGSetChannelBoundsfunction).compressSize- Contains a pointer to the dimensions of the filter buffer. This buffer should be larger than the destination buffer. The sequence grabber component sets this parameter to
nil, or it sets the coordinates of this rectangle to 0 (specifying an empty rectangle), to stop filtering the input source video data.DESCRIPTION
If the sequence grabber component establishes a filter buffer for a channel, your channel component should place its captured video image into the filter buffer and then copy the image into the destination buffer. This process may be too slow for some record operations, but it can be useful during controlled record operations (where the source video can be read on a frame-by-frame basis).RESULT CODE
cantDoThatInCurrentMode -9402 Request invalid in current mode
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