On 6/4/06, Mathieu Bouchard matju@artengine.ca wrote:
On Sun, 4 Jun 2006, chris clepper wrote:
Can you go into more detail about the revisions to block~? My rough calculations put a 720x480 YCbCr image at about 64 times the data of a single 96khz audio signal. RGBA is double that.
How do you compute that?
DV-NTSC is 720 px * 480 px * 30 Hz * 2 samples/px^2 = 20736000 samples/s DV-PAL is 720 px * 576 px * 25 Hz * 2 samples/px^2 = 20736000 samples/s 96 kHz mono is 96000 Hz * 1 samples = 96000 samples/s
and 20736000/96000 = exactly 216 = 6*6*6 but closest powers of 2 are 2^7 = 128 and 2^8 = 256. (comparing with stereo sound doesn't change the relative closeness of powers of two)
I forgot to make the video signal 4 bytes per channel in my calculation. If you compare the 4 byte audio to single byte per channel video then it is 54 times the data. 64 is the next power of two.
Your numbers are the right ones to use.