nCine::AicaAudioDevice class
#include <nCine/Audio/Backends/AICA/AicaAudioDevice.h>

Dreamcast implementation of IAudioDevice on top of the AICA.

Talks to the sound processor through KallistiOS directly instead of going through an OpenAL port. The AICA is a 64-channel wavetable synthesizer with 2 MB of sound RAM of its own, which is what makes audio nearly free in main memory here: a fully loaded sound lives in that separate pool and the SH4 only ever touches it again to change a volume.

The two kinds of player map onto two different parts of the hardware:

A AudioBufferPlayer becomes one AICA channel (two for a stereo buffer, since a channel is mono) playing a sample out of sound RAM. Whether it has finished is read back from the hardware with snd_is_playing(), so nothing has to be predicted from timers.
A AudioStreamPlayer becomes one of KallistiOS's snd_stream handles, whose driver on the ARM keeps a ring buffer in sound RAM topped up from a callback. The callback is served out of the queue this class keeps, so the streaming players still see the queue interface they expect. There are only MaxStreams of these.

As with AsndAudioDevice the hardware has no notion of a listener, so panning and distance attenuation are computed here and folded into the channel volume and pan. The AICA does have a low-pass filter per channel, but the driver leaves it switched off and does not expose it, so setSourceLowPass() does nothing.

Base classes

class AudioDeviceBase: Backend-independent part of an audio device.

Constructors, destructors, conversion operators

AicaAudioDevice()
~AicaAudioDevice() override

Public functions

auto isValid() const -> bool override: Returns true if the device was initialized successfully.
auto name() const -> const char* override: Returns the name of the underlying device.
void setGain(float gain) override: Sets the listener gain (master volume).
void updateListener(const Vector3f& position, const Vector3f& velocity) override: Updates the position and velocity of the listener.
auto nativeFrequency() -> std::int32_t override: Returns the native sample rate of the device.
auto registerPlayer(IAudioPlayer* player) -> std::uint32_t override: Registers a player so it receives state and buffer queue updates, returning its source id.
void updatePlayers() override: Updates the state of every registered player, including the buffer queue of stream players.
auto createBuffer(BufferUsage usage) -> std::uint32_t override: Creates an empty backend buffer, returning its id or 0 on failure.
void deleteBuffer(std::uint32_t bufferId) override: Destroys a buffer previously returned by createBuffer().
auto uploadBuffer(std::uint32_t bufferId, BufferFormat format, const void* data, std::int32_t size, std::int32_t frequency) -> bool override: Replaces the contents of a buffer with the specified samples.
void setSourceBuffer(std::uint32_t sourceId, std::uint32_t bufferId) override: Attaches a buffer to a source for non-streamed playback, 0 detaches the current one.
void setSourceGain(std::uint32_t sourceId, float gain) override: Sets the gain of a source.
void setSourcePitch(std::uint32_t sourceId, float pitch) override: Sets the pitch of a source, as a multiplier of its natural playback rate.
void setSourceLooping(std::uint32_t sourceId, bool looping) override: Sets whether a source repeats its attached buffer.
void setSourceRelative(std::uint32_t sourceId, bool relative) override: Sets whether the position of a source is relative to the listener.
void setSourcePosition(std::uint32_t sourceId, const Vector3f& position) override: Sets the position of a source, in physical units.
void setSourceLowPass(std::uint32_t sourceId, float value) override: Sets the low-pass amount of a source, 1.0f disables the filter.
auto sourceSampleOffset(std::uint32_t sourceId) -> std::int32_t override: Returns the playback position of a source in samples.
void setSourceSampleOffset(std::uint32_t sourceId, std::int32_t offset) override: Sets the playback position of a source in samples.
void playSource(std::uint32_t sourceId) override: Starts or resumes a source.
void pauseSource(std::uint32_t sourceId) override: Pauses a source at its current position.
void stopSource(std::uint32_t sourceId) override: Stops a source.
auto isSourcePlaying(std::uint32_t sourceId) -> bool override: Returns true if a source is still producing sound.
void queueBuffer(std::uint32_t sourceId, std::uint32_t bufferId) override: Appends a buffer to the streaming queue of a source.
auto numProcessedBuffers(std::uint32_t sourceId) -> std::int32_t override: Returns the number of queued buffers a source has finished playing.
void unqueueBuffers(std::uint32_t sourceId, std::int32_t count, std::uint32_t* bufferIds) override: Removes the specified number of played buffers from the front of the queue.
void suspendDevice() override: Suspends the audio device.
void resumeDevice() override: Resumes the audio device.

Function documentation

void nCine::AicaAudioDevice::unqueueBuffers(std::uint32_t sourceId, std::int32_t count, std::uint32_t* bufferIds) override

Removes the specified number of played buffers from the front of the queue.