Yunus Shaikh
b3b6178347
The 28- and 32-byte M4AAC parameter blocks carry two fields at offsets 24 and 28 whose range errors fpPS4 names SCE_AUDIODEC_ERROR_M4AAC_INVALID_ENABLE_NONDELAY_OUTPUT (0x807F0305) and SCE_AUDIODEC_ERROR_M4AAC_INVALID_SURROUND_CHANNEL_INTERLEAVE_ORDER (0x807F0306). shadPS4's AJM AAC decoder outputs every decoded frame from the first one on when non-delay output is enabled, which is what the decoder here does, so a decoder created with non-delay output 1 is accepted and decodes as before. Surround channel interleave orders 1 and 2 still throw, now naming the order: no source says which order each value selects. Name both errors and test that every access unit yields its frame from the first one with non-delay output enabled.
2.8 KiB
libSceAudiodec technical debt
Unknown function info
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M4AAC extended parameters: 28-byte and 32-byte parameter variants add fields at offsets 24 and 28, named by their range errors (
0x807F0305SCE_AUDIODEC_ERROR_M4AAC_INVALID_ENABLE_NONDELAY_OUTPUT,0x807F0306SCE_AUDIODEC_ERROR_M4AAC_INVALID_SURROUND_CHANNEL_INTERLEAVE_ORDER, in fpPS4'sps4_libsceaudiodec.pas). Non-delay output 1 decodes every access unit to its own PCM from the first one on, as shadPS4's AJM AAC decoder does withEnableNondelayOutput; without that flag shadPS4 holds back the first 2 frames. Non-delay output 0 still decodes the same way, with no frame held back: no measurement shows whether the console delays it. Surround channel interleave orders 1 and 2 throw: shadPS4 names two AJM orders (ExtlExtrLsRs,LsRsExtlExtr) but uses neither, and no source says which value selects which order or which order 0 is. -
sceAudiodecDecode (libSceAudiodec) - a raw M4AAC stream carries no channel configuration, so the decoder tries the mono/stereo configuration and then configurations 3 to 7 within
ui_max_channelsuntil one decodes the first access unit, and keeps that one. No reference documents how the library picks the layout (shadPS4 maps the channel count straight to the configuration; SharpProspero only describes the maximum). With the stereo configuration a mono raw stream decodes as 2 channels, so 2 is reported, not 1 -
sceAudiodecDecode (libSceAudiodec) - the HE-AAC handling follows one console measurement of an HE-AAC v2 ADTS stream: SBR output at 48 kHz in one channel with
ui_enable_heaac1, the 24 kHz mono core with 0. Not measured: whether the console, like FFmpeg, decodes a stream without SBR data in its first access unit as AAC-LC withui_enable_heaac1, and what it reports inui_sampling_freqandui_heaacwithui_enable_heaac0 (here the rate of the returned PCM and 0)
Functional
- sceAudiodecDecode (libSceAudiodec) - an ADTS stream with channel configuration 0 (layout in a program config element) is still parsed by FFmpeg, so
ui_enable_heaac0 does not remove its SBR and a mono one with Parametric Stereo comes out as stereo. - libSceAudiodec accepts only 16-bit PCM, and float PCM for ATRAC9 and M4AAC, as
sceAudiodecCreateDecoderdid in a payload process on a PS5 (firmware 13.60), which returnedERROR_INVALID_WORD_LENGTHforiBwPcm0, 3 and -1 with each codec and for float with MP3; other word sizes are assumed to fail the same way. ATRAC9 decoding is covered only by configuration and error tests, as no ATRAC9 encoder is available for a fixture.