se.cherkasov
d94fbb894b
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Three audio bugs fixed: 1. DMC loop mode skipped the last byte of each sample iteration. provide_dmc_dma_byte() was immediately setting dmc_dma_request on loop restart while the sample buffer was still full, causing the while-loop in clock_cpu_cycles to service a second DMA immediately and overwrite the valid buffer. Per NES hardware spec, the reader only fills an empty buffer — the request is now left to clock_dmc when the output unit actually empties the buffer into the shift register. Fixes intermittent clicking/crackling in games that use looped DMC samples (BGM, SFX). 2. Missing DC blocker (high-pass filter) in AudioMixer. The NES APU has a capacitor-coupled output stage that blocks DC bias. Without it, abrupt channel state changes (length counter expiry, sweep mute, triangle period < 2) produce DC steps that manifest as audible clicks. Added a one-pole IIR high-pass filter at ~5 Hz applied after the existing low-pass filter. 3. cpal stream was opened at application startup with BufferSize::Fixed(256), forcing PipeWire/PulseAudio to run the entire audio graph at a 5.3 ms quantum. This disrupted other audio applications (browsers, media players) even when no ROM was loaded. Fixed by: (a) creating the stream lazily on the first push_samples call so no device is touched until a ROM is running, and (b) switching to BufferSize::Default so the audio server chooses the quantum instead of the emulator imposing one. Ring buffer capacity increased from 1536 to 4096 samples to absorb larger server quanta.