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To calculate the size in kilobytes (K) of one frame of uncompressed video, use the following formula:
Frame size K = ([Pixel Width x Pixel Height x Bit Depth] / 8) / 1024
Where 8 represents an 8-bit byte, and 1024 equals the number of bytes per kilobytes. For example, the size in kilobytes of an uncompressed frame of full-size (640 x 480), 24-bit video is:
Frame size K = ([640 x 480 x 24] / 8) / 1024 = 900K
To determine the file size of one second of uncompressed video, multiply the image size by the number of frames per second (fps). For example, one second of uncompressed, full-size, full-speed (30 fps), 24-bit video is:
900K x 30 = 27 MB
To determine how compression affects file size, divide the file size by the compression ratio. For example, a 10:1 compression ratio will make a 27 MB file 2.7 MB.
The following information compares the disk space requirements for NTSC video (640 x 480 and 29.97fps) compressed using various date rates. The data rate information is shown for each of the standard data rate calculation methods: by frames and by seconds:
60 KB/Frame: 1.8 MB/sec 9.25 min/GB
80 KB/Frame: 2.4 MB/sec 6.94 min/GB
100 KB/Frame: 3.0 MB/sec 5.56 min/GB
120 KB/Frame: 3.6 MB/sec 4.63 min/GB
140 KB/Frame: 4.2 MB/sec 3.97 min/GB
160 KB/Frame: 4.8 MB/sec 3.47 min/GB
180 KB/Frame: 5.4 MB/sec 3.08 min/GB
200 KB/Frame: 6.0 MB/sec 2.78 min/GB
The DV standard of 720 x 480 video with 5:1 compression requires 3.6 MB/sec and 4.63 min/GB.
-courtesy of Adobe
Ergo, your 2GB = 4.63min/GB * 2
This message has been edited since posting. Last time this message was edited on 20. January 2003 @ 23:33
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