MarkZ
2nd March 2011, 19:45
I've been experimenting with some settings in the hope that I can find a good compromise between quality, file size, and decoding CPU usage. Ultimately, I want the encodes to be compatible with the original xbox.
I can get it to work at full res (720x480) if I turn off deblocking and cabac, and use a vbv buffer:rate setting of 1500:2500. Problem solved.
I'd like to get my file sizes down a little bit (perhaps by implementing CABAC), but no matter what setting combination I use, it seems the only way I can do this is by decreasing bitrate, which I don't want to do because it leads to obvious decreases in quality. At present, my mean bitrates are hovering around 1400. When I flip on CABAC, I drop frames.
Question:
Are there any obvious CPU *playback* optimizations I'm overlooking? Yes, I know, decreasing res could solve it too, but I don't want that either.
The relevant settings look like this:
CRF=21-23.5 (depending on the source, etc)
b-frames = 3 (increasing this didn't seem to have much effect on file size)
adaptive b-frames = 2
ref frames = 8 (reducing this didn't seem to reduce CPU decoding)
Max/Min GOP = 250/25 (not sure what this would do)
qcomp=0.5 (I like a lower qcomp value for vbv-limited encodes when trying to reduce file size)
rc-lookahead=100
mb-tree=1
VAQ=1
me=umh, range=24 (changing range didn't do much, neither did switching to esa, surprisingly)
subme=9 (would this have an effect on cpu playback?)
trellis=1
I can get it to work at full res (720x480) if I turn off deblocking and cabac, and use a vbv buffer:rate setting of 1500:2500. Problem solved.
I'd like to get my file sizes down a little bit (perhaps by implementing CABAC), but no matter what setting combination I use, it seems the only way I can do this is by decreasing bitrate, which I don't want to do because it leads to obvious decreases in quality. At present, my mean bitrates are hovering around 1400. When I flip on CABAC, I drop frames.
Question:
Are there any obvious CPU *playback* optimizations I'm overlooking? Yes, I know, decreasing res could solve it too, but I don't want that either.
The relevant settings look like this:
CRF=21-23.5 (depending on the source, etc)
b-frames = 3 (increasing this didn't seem to have much effect on file size)
adaptive b-frames = 2
ref frames = 8 (reducing this didn't seem to reduce CPU decoding)
Max/Min GOP = 250/25 (not sure what this would do)
qcomp=0.5 (I like a lower qcomp value for vbv-limited encodes when trying to reduce file size)
rc-lookahead=100
mb-tree=1
VAQ=1
me=umh, range=24 (changing range didn't do much, neither did switching to esa, surprisingly)
subme=9 (would this have an effect on cpu playback?)
trellis=1