PSP 9 video - suitable quantization matrix

[gabbon]

Hi
I am using PSP 9 video to encode videos into AVC for PSP. I experimented with Qscale settings but I cannot find optimal settings. Qscale=23 is really nice (for action and clear sharp scenes) until there is some dark scene (I am encoding anime) where there is visible lack of quality....so I have to use too high value of Qscale (17 works) but then its too much of a waste and it could be much more compact without real decrease in quality. I heard that there are some custom matrixes, is there some with more "flat" distribution of bitrate?
The problem could be that I heard that PSP 9 Video uses FFdshow as codec source....so even if I find matrix how do I export it so that PSP9 Video could use it.
Thanks

[Manao]

PSP9 doesn't support custom matrices. What you want is either the constant rate factor option, or simply a two passes encoding.

Anyway, matrices aren't related to the bitrate in the way you think, their effects is a lot more subtle and complicated to explain in a few words.

[celtic_druid]

ffdshow? Are you sure it isn't ffmpeg?
Doesn't look like ffmpeg supports CQM's with x264. ffdshow does. Can the PSP decode them anyway?

[gabbon]

you are right, I made a mistake its ffmpeg.
Whether PSP can decode x264 with CQMs is a question I would like to know answer to too....


to Manao: Could you (if you know) send me some link to article with description of what actually those matrices are doing....I was looking for it but I wasnt succesful, and I would like to know exactly how it works
thx

[Sharktooth]

PSP doesnt support High Profile... hence it CAN'T decode streams made with custom matrix quantization.
Custom matrices alter the standard codec way to quantize and the scaling is defined by the matrix.