11Pinnacle Systems TARGA 3000
An example of how to calculate these numbers for uncompressed YUV (Y, B-Y, R-Y) is as
follows:
First calculate total bytes per frame for one second of uncompressed YUV (NTSC) video.
29.97 frames per second x 720 pixels wide x 486 pixels high x 2 bytes per pixel = 20,974,205 total bytes per second
Two bytes per pixel comes from the fact that TARGA 3000 supports a compression that
uses YUV 4:2:2 video. For every four pixels of video there is 4 bytes of Y, 2 bytes of U,
and 2 bytes of V which is a total of eight bytes for every four pixels, or two bytes per pixel.
Note: Some people calculate uncompressed NTSC video using RGB 4:4:4 video which yields three bytes
per pixel, but this is incorrect.
To these 20,974,205 bytes add audio at 48 kHz, 16 bit, stereo:
48,000 audio samples per second x 2 bytes per sample x 2 samples for stereo = 192,000 bytes
The total size for one second of uncompressed NTSC video and CD quality stereo audio is:
20,974,205 bytes per second + 192,000 bytes of audio per second = 21,166,205 bytes per second (roughly
~
21 MBytes)
To calculate the values in any row of the table, say the 6 MByte/sec row, do the following:
First, derive the compression ratio which is:
21 MByte ÷ 6 MByte = 3.5
Then, calculate the frame size for 30 frame/sec video:
6 MByte ÷ 30 frames = 200 KBytes per frame
To calculate “Minutes Per GByte,” first calculate the size for one minute of video at 6
MByte/sec:
6 MByte per second x 60 seconds per minute = 360 MByte per minute
Finally, divide one GByte by the file size of a minute of video to determine how many
minutes per GByte:
1 GByte ÷ 360 MByte = 2.78 minutes per GByte
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