sceMpegBaseCscAvc is the top of a profile during video playback, so the loop
that does the work becomes MpegCscRange - a pure function with the HLE plumbing
left behind - and TestMpegCsc measures and checks it.
The measuring half reports megapixels per second for a 480x272 frame in each of
the four pixel formats. The checking half compares against the conversion
written out longhand, over whole frames and over partial ranges with odd offsets
and sizes, plus one-pixel, one-row and one-column ranges and one that reaches
the far edge of the frame. Those are the cases an optimized version gets wrong:
chroma is half resolution, so an odd left edge starts mid-sample, and anything
handling two pixels at a time has to deal with the leftover. The destination is
padded and prefilled, so writing outside the range fails too.
This is only the move - the loop is the same one, so the numbers it gives are
the baseline to improve on. On a Snapdragon X Elite it runs at about 300 MPix/s,
0.44ms for a frame.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
