sprit
20th January 2003, 20:46
I'm making a simple debugview output summariser(sp?), a little (or rather a lot :) like xda). While trying to clean it up I ran into a couple of spots where I don't know how to interpret the output from xvid.
[list=1] Quantizer for B-frames
Is the quantizer output correct or should I feed the program the used B-frame quant ratio and offset and calculate the quantizer from that?
Switching quantization type
To calculate AVI overhead I just add '24 * number of frames' bytes. I read that the overhead per qt switch is 140 bytes. Is this correct? I assume that that's in the mpeg bitstream, is it the same in the AVI? Is the overhead already included in the framesize?
Delayed frame
Where do the real frame, in particular the info about it, go?
Packed bitstream
Is the indicated 'padded' frames the [empty] frames? If so, should they (and their size) be ignored? Also, where do I find the info re. the BP-pair and how do I split it into info about the B and the P separately?
[/list=1]Right now I'm ignoring both delayed and padded frames. The first seems wrong (when encoding with f.ex. 3 B-frames I get the total number of frames three less than it should be) but the second right (results in the currect number of total frames). Anyone know how these things actually work and can give some info?
[list=1] Quantizer for B-frames
Is the quantizer output correct or should I feed the program the used B-frame quant ratio and offset and calculate the quantizer from that?
Switching quantization type
To calculate AVI overhead I just add '24 * number of frames' bytes. I read that the overhead per qt switch is 140 bytes. Is this correct? I assume that that's in the mpeg bitstream, is it the same in the AVI? Is the overhead already included in the framesize?
Delayed frame
Where do the real frame, in particular the info about it, go?
Packed bitstream
Is the indicated 'padded' frames the [empty] frames? If so, should they (and their size) be ignored? Also, where do I find the info re. the BP-pair and how do I split it into info about the B and the P separately?
[/list=1]Right now I'm ignoring both delayed and padded frames. The first seems wrong (when encoding with f.ex. 3 B-frames I get the total number of frames three less than it should be) but the second right (results in the currect number of total frames). Anyone know how these things actually work and can give some info?