HP SVA V2.0 Parallel Compositing Reference Guide

rowSpan = channel.size * channel.rowLength +
modulo( channel.size * channel.rowLength, channel.alignment )
address of (x,y) = channel.address + y * rowSpan + x * channel.size
A host may call pcFrameResultChannel one or more times, provided the PC_OUTPUT_WIDTH
and PC_OUTPUT_HEIGHT context properties are set to non-zero values. Each call may request
the same or a different channel. Setting either PC_OUTPUT_WIDTH or PC_OUTPUT_HEIGHT to
0 indicates that the host will not request a result.
The arrays retrieved by pcFrameResultChannel are managed by the Library. The calling
program may not modify them; it should extract any information from the arrays before the next
call to pcFrameBegin.
The PC_RETAIN_OUTPUT context property requires that the Library not reuse the arrays for an
additional number of frames as specified by the property. This extends the time the calling
program has to retrieve the information. For example, when set to 2, PC_RETAIN_OUTPUT
supports double buffering the output. (PC_RETAIN_OUTPUT_LIMIT is 2 for the HP
implementation.) The application can composite frame n + 1 while it is retrieving the pixels
for frame n.
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