#include "audio_engine.h" #include #include #include #define AUDIO_ENGINE_SOUND_BUFFERS 8 struct AudioEngineSoundBuffer { bool active; unsigned int size; int bitsPerSample; int channels; int rate; void* data; int volume; bool playing; bool looping; unsigned int pos; SDL_AudioStream* stream; std::recursive_mutex mutex; }; extern bool gProgramIsActive; static bool soundBufferIsValid(int soundBufferIndex); static void audioEngineMixin(void* userData, Uint8* stream, int length); static SDL_AudioSpec gAudioEngineSpec; static SDL_AudioDeviceID gAudioEngineDeviceId = -1; static AudioEngineSoundBuffer gAudioEngineSoundBuffers[AUDIO_ENGINE_SOUND_BUFFERS]; static bool soundBufferIsValid(int soundBufferIndex) { return soundBufferIndex >= 0 && soundBufferIndex < AUDIO_ENGINE_SOUND_BUFFERS; } static void audioEngineMixin(void* userData, Uint8* stream, int length) { memset(stream, gAudioEngineSpec.silence, length); if (!gProgramIsActive) { return; } for (int index = 0; index < AUDIO_ENGINE_SOUND_BUFFERS; index++) { AudioEngineSoundBuffer* soundBuffer = &(gAudioEngineSoundBuffers[index]); std::lock_guard lock(soundBuffer->mutex); if (soundBuffer->active && soundBuffer->playing) { int srcFrameSize = soundBuffer->bitsPerSample / 8 * soundBuffer->channels; unsigned char buffer[1024]; int pos = 0; while (pos < length) { int remaining = length - pos; if (remaining > sizeof(buffer)) { remaining = sizeof(buffer); } // TODO: Make something better than frame-by-frame convertion. SDL_AudioStreamPut(soundBuffer->stream, (unsigned char*)soundBuffer->data + soundBuffer->pos, srcFrameSize); soundBuffer->pos += srcFrameSize; int bytesRead = SDL_AudioStreamGet(soundBuffer->stream, buffer, remaining); if (bytesRead == -1) { break; } SDL_MixAudioFormat(stream + pos, buffer, gAudioEngineSpec.format, bytesRead, soundBuffer->volume); if (soundBuffer->pos >= soundBuffer->size) { if (soundBuffer->looping) { soundBuffer->pos %= soundBuffer->size; } else { soundBuffer->playing = false; break; } } pos += bytesRead; } } } } bool audioEngineInit() { if (SDL_InitSubSystem(SDL_INIT_AUDIO) == -1) { return false; } SDL_AudioSpec desiredSpec; desiredSpec.freq = 22050; desiredSpec.format = AUDIO_S16; desiredSpec.channels = 2; desiredSpec.samples = 1024; desiredSpec.callback = audioEngineMixin; gAudioEngineDeviceId = SDL_OpenAudioDevice(NULL, 0, &desiredSpec, &gAudioEngineSpec, SDL_AUDIO_ALLOW_ANY_CHANGE); if (gAudioEngineDeviceId == -1) { return false; } SDL_PauseAudioDevice(gAudioEngineDeviceId, 0); return true; } void audioEngineExit() { if (gAudioEngineDeviceId != -1) { SDL_CloseAudioDevice(gAudioEngineDeviceId); gAudioEngineDeviceId = -1; } SDL_QuitSubSystem(SDL_INIT_AUDIO); } void audioEnginePause() { if (gAudioEngineDeviceId != -1) { SDL_PauseAudioDevice(gAudioEngineDeviceId, 1); } } void audioEngineResume() { if (gAudioEngineDeviceId != -1) { SDL_PauseAudioDevice(gAudioEngineDeviceId, 0); } } int audioEngineCreateSoundBuffer(unsigned int size, int bitsPerSample, int channels, int rate) { for (int index = 0; index < AUDIO_ENGINE_SOUND_BUFFERS; index++) { AudioEngineSoundBuffer* soundBuffer = &(gAudioEngineSoundBuffers[index]); std::lock_guard lock(soundBuffer->mutex); if (!soundBuffer->active) { soundBuffer->active = true; soundBuffer->size = size; soundBuffer->bitsPerSample = bitsPerSample; soundBuffer->channels = channels; soundBuffer->rate = rate; soundBuffer->volume = SDL_MIX_MAXVOLUME; soundBuffer->playing = false; soundBuffer->looping = false; soundBuffer->pos = 0; soundBuffer->data = malloc(size); soundBuffer->stream = SDL_NewAudioStream(bitsPerSample == 16 ? AUDIO_S16 : AUDIO_S8, channels, rate, gAudioEngineSpec.format, gAudioEngineSpec.channels, gAudioEngineSpec.freq); return index; } } return -1; } bool audioEngineSoundBufferRelease(int soundBufferIndex) { if (!soundBufferIsValid(soundBufferIndex)) { return false; } AudioEngineSoundBuffer* soundBuffer = &(gAudioEngineSoundBuffers[soundBufferIndex]); std::lock_guard lock(soundBuffer->mutex); if (!soundBuffer->active) { return false; } soundBuffer->active = false; free(soundBuffer->data); soundBuffer->data = NULL; SDL_FreeAudioStream(soundBuffer->stream); soundBuffer->stream = NULL; return true; } bool audioEngineSoundBufferSetVolume(int soundBufferIndex, int volume) { if (!soundBufferIsValid(soundBufferIndex)) { return false; } AudioEngineSoundBuffer* soundBuffer = &(gAudioEngineSoundBuffers[soundBufferIndex]); std::lock_guard lock(soundBuffer->mutex); if (!soundBuffer->active) { return false; } soundBuffer->volume = volume; return true; } bool audioEngineSoundBufferGetVolume(int soundBufferIndex, int* volumePtr) { if (!soundBufferIsValid(soundBufferIndex)) { return false; } AudioEngineSoundBuffer* soundBuffer = &(gAudioEngineSoundBuffers[soundBufferIndex]); std::lock_guard lock(soundBuffer->mutex); if (!soundBuffer->active) { return false; } *volumePtr = soundBuffer->volume; return true; } bool audioEngineSoundBufferSetPan(int soundBufferIndex, int pan) { if (!soundBufferIsValid(soundBufferIndex)) { return false; } AudioEngineSoundBuffer* soundBuffer = &(gAudioEngineSoundBuffers[soundBufferIndex]); std::lock_guard lock(soundBuffer->mutex); if (!soundBuffer->active) { return false; } // NOTE: Audio engine does not support sound panning. I'm not sure it's // even needed. For now this value is silently ignored. return true; } bool audioEngineSoundBufferPlay(int soundBufferIndex, unsigned int flags) { if (!soundBufferIsValid(soundBufferIndex)) { return false; } AudioEngineSoundBuffer* soundBuffer = &(gAudioEngineSoundBuffers[soundBufferIndex]); std::lock_guard lock(soundBuffer->mutex); if (!soundBuffer->active) { return false; } soundBuffer->playing = true; if ((flags & AUDIO_ENGINE_SOUND_BUFFER_PLAY_LOOPING) != 0) { soundBuffer->looping = true; } return true; } bool audioEngineSoundBufferStop(int soundBufferIndex) { if (!soundBufferIsValid(soundBufferIndex)) { return false; } AudioEngineSoundBuffer* soundBuffer = &(gAudioEngineSoundBuffers[soundBufferIndex]); std::lock_guard lock(soundBuffer->mutex); if (!soundBuffer->active) { return false; } soundBuffer->playing = false; return true; } bool audioEngineSoundBufferGetCurrentPosition(int soundBufferIndex, unsigned int* readPosPtr, unsigned int* writePosPtr) { if (!soundBufferIsValid(soundBufferIndex)) { return false; } AudioEngineSoundBuffer* soundBuffer = &(gAudioEngineSoundBuffers[soundBufferIndex]); std::lock_guard lock(soundBuffer->mutex); if (!soundBuffer->active) { return false; } if (readPosPtr != NULL) { *readPosPtr = soundBuffer->pos; } if (writePosPtr != NULL) { *writePosPtr = soundBuffer->pos; if (soundBuffer->playing) { // 15 ms lead // See: https://docs.microsoft.com/en-us/previous-versions/windows/desktop/mt708925(v=vs.85)#remarks *writePosPtr += soundBuffer->rate / 150; *writePosPtr %= soundBuffer->size; } } return true; } bool audioEngineSoundBufferSetCurrentPosition(int soundBufferIndex, unsigned int pos) { if (!soundBufferIsValid(soundBufferIndex)) { return false; } AudioEngineSoundBuffer* soundBuffer = &(gAudioEngineSoundBuffers[soundBufferIndex]); std::lock_guard lock(soundBuffer->mutex); if (!soundBuffer->active) { return false; } soundBuffer->pos = pos % soundBuffer->size; return true; } bool audioEngineSoundBufferLock(int soundBufferIndex, unsigned int writePos, unsigned int writeBytes, void** audioPtr1, unsigned int* audioBytes1, void** audioPtr2, unsigned int* audioBytes2, unsigned int flags) { if (!soundBufferIsValid(soundBufferIndex)) { return false; } AudioEngineSoundBuffer* soundBuffer = &(gAudioEngineSoundBuffers[soundBufferIndex]); std::lock_guard lock(soundBuffer->mutex); if (!soundBuffer->active) { return false; } if (audioBytes1 == NULL) { return false; } if ((flags & AUDIO_ENGINE_SOUND_BUFFER_LOCK_FROM_WRITE_POS) != 0) { if (!audioEngineSoundBufferGetCurrentPosition(soundBufferIndex, NULL, &writePos)) { return false; } } if ((flags & AUDIO_ENGINE_SOUND_BUFFER_LOCK_ENTIRE_BUFFER) != 0) { writeBytes = soundBuffer->size; } if (writePos + writeBytes <= soundBuffer->size) { *(unsigned char**)audioPtr1 = (unsigned char*)soundBuffer->data + writePos; *audioBytes1 = writeBytes; if (audioPtr2 != NULL) { *audioPtr2 = NULL; } if (audioBytes2 != NULL) { *audioBytes2 = 0; } } else { unsigned int remainder = writePos + writeBytes - soundBuffer->size; *(unsigned char**)audioPtr1 = (unsigned char*)soundBuffer->data + writePos; *audioBytes1 = soundBuffer->size - writePos; if (audioPtr2 != NULL) { *(unsigned char**)audioPtr2 = (unsigned char*)soundBuffer->data; } if (audioBytes2 != NULL) { *audioBytes2 = writeBytes - (soundBuffer->size - writePos); } } // TODO: Mark range as locked. return true; } bool audioEngineSoundBufferUnlock(int soundBufferIndex, void* audioPtr1, unsigned int audioBytes1, void* audioPtr2, unsigned int audioBytes2) { if (!soundBufferIsValid(soundBufferIndex)) { return false; } AudioEngineSoundBuffer* soundBuffer = &(gAudioEngineSoundBuffers[soundBufferIndex]); std::lock_guard lock(soundBuffer->mutex); if (!soundBuffer->active) { return false; } // TODO: Mark range as unlocked. return true; } bool audioEngineSoundBufferGetStatus(int soundBufferIndex, unsigned int* statusPtr) { if (!soundBufferIsValid(soundBufferIndex)) { return false; } AudioEngineSoundBuffer* soundBuffer = &(gAudioEngineSoundBuffers[soundBufferIndex]); std::lock_guard lock(soundBuffer->mutex); if (!soundBuffer->active) { return false; } if (statusPtr == NULL) { return false; } *statusPtr = 0; if (soundBuffer->playing) { *statusPtr |= AUDIO_ENGINE_SOUND_BUFFER_STATUS_PLAYING; if (soundBuffer->looping) { *statusPtr |= AUDIO_ENGINE_SOUND_BUFFER_STATUS_LOOPING; } } return true; }