Proposal: opt-in continuous camera capture API

[SolveSoul]

The current ps2cam API is caller-driven: applications read packets or assemble a frame when they need one.

That's useful for snapshots and intermittent capture. For real-time camera applications, it may also be useful to offer an opt-in continuous-capture mode where the IOP keeps receiving and assembling frames, while the EE retrieves the newest complete frame when ready.

I am experimenting with this in a homebrew project and would be happy to contribute an implementation, but I would like feedback on the API and architecture before preparing a PR. For the homebrew project, I needed local SDK patches to support continuous video capture. This could open up more EyeToy-style homebrew possibilities.

Initial shape:

int PS2CamStartFrameCapture(int handle);
int PS2CamReadLatestFrame(int handle, void *buffer, int buffer_size);
int PS2CamStopFrameCapture(int handle);

Key compatibility goals:

• Existing packet and single-frame APIs retain their current behaviour.
• Continuous capture is an additional opt-in mode. It is mutually exclusive with caller-driven reads on the same handle.
• Capture state and buffers are per handle.
• Stopping or closing a device cleanly terminates its capture worker.
• New RPC commands are version/capability-gated.

I’m also looking for input on implementation placement: should this be a small adjacent capture module, or remain in ps2cam.c?