Audio and Media

Audio and Media

Audio and video are layered compatibility problems. A decoder producing samples does not establish that PSP API, scheduling, buffering, and host-device contracts are all correct.

Audio path

flowchart LR
    A["Guest API<br/>returns + ownership"] --> B["Stream state<br/>logical + ring offsets"]
    B --> C["Decode / SAS<br/>frames + mixing"]
    C --> D["Scheduler<br/>timing + wakeups"]
    D --> E["Host queue<br/>SDL3 device output"]

Loading

Layer	Questions to preserve
Guest API	Return values, error paths, buffer ownership, and observable state.
Stream state	Logical position versus physical ring-buffer location.
Codec/mixer	Priming, frame boundaries, SAS behavior, and sample format.
Timing	Delay, release, preemption, callback, and queue deadlines.
Host device	Output routing, queued audio, and device state.

Code map

Path	Role
src/rt/audio.c	PSP audio services mapped to SDL3 host audio.
src/rt/atrac3p/ and src/rt/atrac3p_bridge.c	ATRAC3+ decoder and HLE bridge.
src/rt/mpeg.c	MPEG/SAS/ATRAC-adjacent runtime behavior.
src/rt/h264_mf.c and src/rt/h264_null.c	Windows Media Foundation path and host-neutral/test alternative.

Warning

Sustained smooth HST audio is not accepted. SAS/mixing, ATRAC3+, and output paths exist in the fuller runtime profile, but rough/stuttering audio remains open in issue #67.

A codec fixture can validate a decoder. Production dispatch or a qualified title route is still needed to establish PSP-visible API behavior. Proprietary streams and derived bytes remain local.

Research: PSP audio and media architecture · ATRAC streaming and ring buffers · Nakagawa case study

Next: Verification and Testing → Debugging