diff --git a/app/streaming/audio/renderers/slaud.cpp b/app/streaming/audio/renderers/slaud.cpp index b876fcf8..e478101c 100644 --- a/app/streaming/audio/renderers/slaud.cpp +++ b/app/streaming/audio/renderers/slaud.cpp @@ -2,9 +2,16 @@ #include +// To reduce CPU load on the Steam Link, we need to accumulate several frames +// before submitting for playback. Higher frames per submission saves more CPU +// but increases audio latency. +#define FRAMES_PER_SUBMISSION 4 + SLAudioRenderer::SLAudioRenderer() : m_AudioContext(nullptr), - m_AudioStream(nullptr) + m_AudioStream(nullptr), + m_AudioBuffer(nullptr), + m_AudioBufferBytesFilled(0) { SLAudio_SetLogFunction(SLAudioRenderer::slLogCallback, nullptr); } @@ -18,10 +25,11 @@ bool SLAudioRenderer::prepareForPlayback(const OPUS_MULTISTREAM_CONFIGURATION* o return false; } + m_AudioBufferSize = SAMPLES_PER_FRAME * sizeof(short) * opusConfig->channelCount * FRAMES_PER_SUBMISSION; m_AudioStream = SLAudio_CreateStream(m_AudioContext, opusConfig->sampleRate, opusConfig->channelCount, - SAMPLES_PER_FRAME * sizeof(short) * opusConfig->channelCount, + m_AudioBufferSize, 1); if (m_AudioStream == nullptr) { SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, @@ -37,6 +45,14 @@ bool SLAudioRenderer::prepareForPlayback(const OPUS_MULTISTREAM_CONFIGURATION* o SLAudioRenderer::~SLAudioRenderer() { + if (m_AudioBufferBytesFilled != 0) { + // We had a buffer in flight when we quit. Just in case + // SLAudio doesn't handle this properly, we'll zero and submit + // it just to be safe. + memset(m_AudioBuffer, 0, m_AudioBufferSize); + SLAudio_SubmitFrame(m_AudioStream); + } + if (m_AudioStream != nullptr) { SLAudio_FreeStream(m_AudioStream); } @@ -48,11 +64,24 @@ SLAudioRenderer::~SLAudioRenderer() bool SLAudioRenderer::submitAudio(short* audioBuffer, int audioSize) { - void* outputBuffer = SLAudio_BeginFrame(m_AudioStream); + if (m_AudioBufferBytesFilled == 0) { + // Get a new audio buffer from SLAudio + m_AudioBuffer = (char*)SLAudio_BeginFrame(m_AudioStream); + if (m_AudioBuffer == nullptr) { + SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "SLAudio_BeginFrame() failed"); + return true; + } + } - if (outputBuffer != nullptr) { - memcpy(outputBuffer, audioBuffer, audioSize); + // Accumulate several frames of audio before submitting to reduce CPU load + SDL_assert(audioSize <= m_AudioBufferSize - m_AudioBufferBytesFilled); + memcpy(&m_AudioBuffer[m_AudioBufferBytesFilled], audioBuffer, audioSize); + m_AudioBufferBytesFilled += audioSize; + + // Submit the buffer when it's full + if (m_AudioBufferBytesFilled == m_AudioBufferSize) { SLAudio_SubmitFrame(m_AudioStream); + m_AudioBufferBytesFilled = 0; } return true; diff --git a/app/streaming/audio/renderers/slaud.h b/app/streaming/audio/renderers/slaud.h index 30715950..c6ac3709 100644 --- a/app/streaming/audio/renderers/slaud.h +++ b/app/streaming/audio/renderers/slaud.h @@ -19,4 +19,7 @@ private: CSLAudioContext* m_AudioContext; CSLAudioStream* m_AudioStream; + char* m_AudioBuffer; + int m_AudioBufferSize; + int m_AudioBufferBytesFilled; };