Here are some factors that seem to affect the speed of the Picture XCMD:
* The amount of RAM allocated to HyperCard -- more memory may help.
* The size of the picture file.
* The type of compression used -- JPEG compression may be a lot slower
than Video compression. Note also that JPEG gives you a smaller file but
may take longer to decompress.
* The parameters you pass to the Picture XCMD -- Files may display
quicker if no parameter for bit-depth (fifth param) is passed. Pass a
fifth parameter only if memory conservation is important. If you try to
display a file at a lower bit depth, it takes time to convert. If you
pass 0 for the bit-depth parameter, then the XCMD does not set up an
offscreen buffer. Hence, the window will seem to appear immediately, but
the picture may take some time to get drawn into the window (it is drawn
as it is decompressed). This method will give you slower updates.
This article is adapted from the Claris Tech Info database.
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