Cut restatement and asides that only made sense against earlier, wrong versions
of the code, and prefer parentheses over paired dashes. Also fix two comments
left stale by the descriptor rework, and record the rule in AGENTS.md.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
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>
Four places were each computing the same sizes and 64-byte-aligned offsets:
the allocation, the recovery sceMpegbase uses, and the readers on both sides.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Decode looked its context up with operator[], so a game that never opened one
would still get an entry and a decoder, and only Delete ever removes those.
Require the context to exist instead.
The gathered PES payloads were likewise kept for the whole boot, so the first
decode of a movie could be handed the last packet of the previous one if the
address came round again. Hand each payload out once.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Same shape as the audio table: one row per open context, with its EDRAM block
and frame buffer allocation. Both are in ME memory, so the addresses shown are
in that space, not in PSP RAM.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Add flash0:/kd/mpeg.prx to the sceUtility module swap, hung off av_mpegbase,
so it loads when DisableHLEFlags::sceMpeg is set. Games that ship their own
sceMpeg_library on the disc never get here and just use theirs.
The piece that was missing to make it work: the access unit address mpeg.prx
passes to sceVideocodecDecode is in Media Engine space, which we can't read.
On hardware sceMpegBasePESpacketCopy DMA'd the payload there first. That copy
is ours, so it now gathers the blocks and sceVideocodec decodes from those,
falling back to main memory for any caller that points at it directly. The
gather is keyed by destination, because that call carries the audio payload
too - video to an ME address, audio to main memory - and handing an ATRAC
packet to the H.264 decoder gets you nothing.
With that, video/mpeg/basic gets a 144x80 frame out of real Sony code driving
our sceVideocodec through ffmpeg. The test still fails overall, as it did
before this branch - it is in tests_next.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
mpeg.prx copies only the four luma buffers into the descriptor it passes to
sceMpegBaseCscAvc, at +0x20, and keeps a stride where the chroma ones would
be - so the conversion had nothing to read. Both ends of this are ours, so the
full set is recovered from the allocation sceVideocodec handed out.
Death Jr. now runs the whole chain: 504 frames decoded by real mpeg.prx through
sceVideocodec, and 505 colour conversions into the game's display buffers at
480x272, no exceptions.
The picture is still black, and the cause is now upstream of all of this: the
decoder itself returns blank frames, so what we feed it isn't the video
elementary stream. The first access unit being 162 bytes was the early sign.
sceMpegBasePESpacketCopy gathers the LLI blocks it is given, and that is
evidently not the whole story - PES headers, or blocks it isn't counting.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
The last piece mpeg.prx needs from us. It decodes through AvcDecoder and writes
the result where sceMpegbase expects to read it: for type 0, the eight-buffer
tiled layout, produced here as the exact inverse of the reader added with the
colour conversion. Type 1 hands back plain planar YUV instead.
The descriptor mpeg.prx passes in is empty - on hardware the Media Engine owns
the frame buffers and reports back where it put them - so they are allocated
here and their addresses filled in, and sceMpegbase can recover the full set
from that allocation afterwards. The list is only read as addresses once it
holds addresses: a caller that leaves small integers there used to take us
straight into a memory exception.
Both those buffers and the block sceVideocodecGetEDRAM hands out live in a
model of the ME's own 2MB of embedded DRAM rather than in either PSP partition,
with a BlockAllocator carving it up. The CPU can't reach ME memory on hardware:
mpeg.prx keeps the EDRAM value and hands it back without ever dereferencing it,
and it has no way to say where the frame buffers should go - sceVideocodecSetMemory
is given a frame size and a buffer count, 480, 272 and 2 for a full-screen movie.
Taking either from the game would push its own allocations around or spend memory
a real PSP never spends, so sceMpegbase reads the frame through a host pointer
into that block instead of through Memory::.
A game can hold several contexts at once - Silent Hill Origins runs two, one
that owns the EDRAM and one that does every decode - so the decoder, the frame
buffers and the EDRAM address are per context, keyed by context address the way
sceAudiocodec keys its decoders. The EDRAM itself the firmware tracks in the
caller's context struct and nowhere else, including refusing a second request
rather than replacing the first, as videocodec_260.prx shows, so we do the same.
Registered at the end of RegisterAllModules, since a savestate stores the
syscall opcode encoding that order.
GetSEI, ScanHeader, GetFrameCrop and the two unnamed NIDs return 0 and log -
mpeg.prx calls them but nothing yet shows what they need to return, and
guessing seemed worse than being loud about it.
Untested: nothing calls this until mpeg.prx is loaded, which is the next step.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
