folta@tove.umd.edu (Wayne Folta) (09/28/89)
A while back, several people asked about how MacVision actually grabs frames. Here is the scoop from their 2.0 manual: To allow for the processing time necessary to assemble the image information in memory, one sample is taken from a horizontal line in consecutive video fields. This makes the effective time for each sample 63.5 microseconds. The time required for MacVision to sample, transmit and assemble in memory the 310,000 samples in a 640 by 480 pixel image is 20 seconds. The output from the MacVision digitizer is a serial bit stream which represents consecutive vertical columns of samples. The data is sent to the Macintosh serial port at 230 kilobits per second... Wayne Folta (folta@tove.umd.edu 128.8.128.42)