mpeg.prx reads the eight frame buffer addresses straight off the front of the
structure sceVideocodec publishes - `lw` at 0x00..0x1C, the same in Daxter's
disc copy (1.3, at 08805698) and in flash0:/kd/mpeg.prx (1.8, at 08805898) -
and takes the dimensions from its own context. We were writing the dimensions
at 0x00/0x04 and the buffers at 0x10, so slots 0 and 1 received 17 and 30 and
the four chroma addresses never arrived at all.
That survived in Daxter only by cancelling out: mpeg.prx hands the same words
back in the descriptor it builds for the colour conversion, which read them
with the same skew. It bites as soon as they are used as real addresses.
So also:
- sceMpegBaseYCrCbCopy moves the frame, rather than copying 48 bytes of
descriptor over the caller's table of destination pointers. mpegbase.prx
builds a DMA list over the eight buffers (080010f8 in mpegbase_260.prx):
flags bit 0 takes 0,1,4,5 and bit 1 takes 2,3,6,7. mpeg.prx always passes 3.
- The chroma buffers are paired like the luma ones, left/right then even/odd
rows, which is what that flag split assumes. Ours grouped them by half, so
the per-buffer sizes disagreed with the caller's.
- The conversion reads the descriptor as mpegbase.prx does, and takes the
buffers from wherever they are: still in the Media Engine, or already copied
into the game's memory.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
