feat(media): add bounded PCM capture, owned snapshots and A/V streaming

packages/audio/src/io/native_capture.zigadded+41-0

Changes to packages/audio/src/io/native_capture.zig

		@@ -0,0 +1,41 @@
	1	+//! Home opaque, header-checked ALSA capture. Build C boundary and link libasound.
	2	+//! Calls serialize; close only after read returns. S16LE mono/stereo, BOOTTIME ns.
	3	+const Handle = opaque {};
	4	+pub const Config = extern struct { sample_rate: u32, channels: u32, block_frames: u32 };
	5	+extern fn home_audio_open(*const Config, [*:0]const u8, *?*Handle) c_int;
	6	+extern fn home_audio_read(*Handle, [*]u8, u32, u32, *u32, *u64, *i64) c_int;
	7	+extern fn home_audio_close(*Handle) void;
	8	+pub const Block = struct { frames: u32, timestamp_ns: u64, clock_error_ns: i64 };
	9	+pub const Capture = struct {
	10	+ handle: *Handle,
	11	+ config: Config,
	12	+ failed: bool = false,
	13	+ pub fn init(cfg: Config, device: [:0]const u8) !Capture {
	14	+ var out: ?*Handle = null;
	15	+ try check(home_audio_open(&cfg, device.ptr, &out));
	16	+ return .{ .handle = out.?, .config = cfg };
	17	+ }
	18	+ pub fn deinit(s: *Capture) void {
	19	+ home_audio_close(s.handle);
	20	+ }
	21	+ pub fn read(s: *Capture, data: []u8, timeout_ms: u32) !?Block {
	22	+ if (s.failed) return error.CaptureFailed;
	23	+ if (data.len < @as(u64, s.config.block_frames) * s.config.channels * 2 or timeout_ms > 1000) return error.InvalidConfiguration;
	24	+ var block: Block = undefined;
	25	+ const rc = home_audio_read(s.handle, data.ptr, @intCast(s.config.block_frames), timeout_ms, &block.frames, &block.timestamp_ns, &block.clock_error_ns);
	26	+ if (rc == 1) return null;
	27	+ check(rc) catch |err| {
	28	+ s.failed = true;
	29	+ return err;
	30	+ };
	31	+ return block;
	32	+ }
	33	+};
	34	+fn check(rc: c_int) !void {
	35	+ return switch (rc) {
	36	+ 0 => {},
	37	+ -1 => error.InvalidConfiguration,
	38	+ -2 => error.OutOfMemory,
	39	+ else => error.CaptureFailed,
	40	+ };
	41	+}