Initial commit.

docs/AUDIO_ENGINE.md

@@ -0,0 +1,27 @@
+# Audio engine requirements
+
+## Real-time callback rules
+
+The callback must not allocate/free memory, lock blocking mutexes, perform
+filesystem/network/console I/O, log, load plugins or samples, call GUI APIs,
+or wait for another thread.
+
+Use preallocated buffers and bounded work. Publish parameter and graph changes
+through a documented real-time-safe mechanism. Verify atomics are lock-free
+where required on the target platform.
+
+## Processing model
+
+Process a bounded number of frames per block. Do not assume a fixed block size
+unless the backend guarantees it. Define maximum frame and event counts and
+safe behavior when those limits are reached.
+
+The initial milestone is offline processing, then a test oscillator -> gain ->
+meter/output graph, then a hardware backend.
+
+## Clock and transport
+
+Audio sample position is the authoritative playback clock. Use integer or
+rational timeline representations to avoid cumulative floating-point drift.
+Define tempo-map conversion and behavior at tempo changes before implementing
+tempo automation.