Initial implementation for Oboe-based playback

1 files changed, 185 insertions, 4 deletions

diff --git a/alc/backends/oboe.cpp b/alc/backends/oboe.cpp
index 54fd0f1c..c999df6f 100644
--- a/alc/backends/oboe.cpp
+++ b/alc/backends/oboe.cpp
@@ -3,21 +3,202 @@
 
 #include "oboe.h"
 
+#include <cassert>
+#include <cstring>
+
+#include "alu.h"
+#include "logging.h"
+
 #include "oboe/Oboe.h"
 
 
+namespace {
+
+constexpr char device_name[] = "Oboe Default";
+
+
+struct OboePlayback final : public BackendBase, public oboe::AudioStreamCallback {
+    OboePlayback(ALCdevice *device) : BackendBase{device} { }
+
+    oboe::ManagedStream mStream;
+
+    oboe::DataCallbackResult onAudioReady(oboe::AudioStream *oboeStream, void *audioData,
+        int32_t numFrames) override;
+
+    void open(const ALCchar *name) override;
+    bool reset() override;
+    bool start() override;
+    void stop() override;
+};
+
+
+oboe::DataCallbackResult OboePlayback::onAudioReady(oboe::AudioStream *oboeStream, void *audioData,
+    int32_t numFrames)
+{
+    assert(numFrames > 0);
+    aluMixData(mDevice, audioData, static_cast<uint32_t>(numFrames),
+        static_cast<uint32_t>(oboeStream->getChannelCount()));
+    return oboe::DataCallbackResult::Continue;
+}
+
+
+void OboePlayback::open(const ALCchar *name)
+{
+    if(!name)
+        name = device_name;
+    else if(std::strcmp(name, device_name) != 0)
+        throw al::backend_exception{ALC_INVALID_VALUE, "Device name \"%s\" not found", name};
+
+    oboe::AudioStreamBuilder builder;
+    builder.setDirection(oboe::Direction::Output);
+    builder.setPerformanceMode(oboe::PerformanceMode::LowLatency);
+
+    oboe::Result result{builder.openManagedStream(mStream)};
+    if(result != oboe::Result::OK)
+        throw al::backend_exception{ALC_INVALID_VALUE, "Failed to create stream. Error: %s",
+            oboe::convertToText(result)};
+}
+
+bool OboePlayback::reset()
+{
+    mStream = nullptr;
+
+    oboe::AudioStreamBuilder builder;
+    builder.setDirection(oboe::Direction::Output);
+    builder.setPerformanceMode(oboe::PerformanceMode::LowLatency);
+    builder.setCallback(this);
+
+    if(mDevice->Flags.get<FrequencyRequest>())
+        builder.setSampleRate(static_cast<int32_t>(mDevice->Frequency));
+    if(mDevice->Flags.get<ChannelsRequest>())
+        builder.setChannelCount((mDevice->FmtChans==DevFmtMono) ? oboe::ChannelCount::Mono
+            : oboe::ChannelCount::Stereo);
+    if(mDevice->Flags.get<SampleTypeRequest>())
+    {
+        oboe::AudioFormat format{oboe::AudioFormat::Unspecified};
+        switch(mDevice->FmtType)
+        {
+        case DevFmtByte:
+        case DevFmtUByte:
+        case DevFmtShort:
+        case DevFmtUShort:
+            format = oboe::AudioFormat::I16;
+            break;
+        case DevFmtInt:
+        case DevFmtUInt:
+        case DevFmtFloat:
+            format = oboe::AudioFormat::Float;
+            break;
+        }
+        builder.setFormat(format);
+    }
+
+    oboe::Result result{builder.openManagedStream(mStream)};
+    if(result == oboe::Result::ErrorInvalidFormat)
+    {
+        builder.setSampleRate(oboe::kUnspecified);
+        builder.setChannelCount(oboe::ChannelCount::Stereo);
+        builder.setFormat(oboe::AudioFormat::Unspecified);
+        result = builder.openManagedStream(mStream);
+    }
+    if(result != oboe::Result::OK)
+        throw al::backend_exception{ALC_INVALID_DEVICE, "Failed to create stream: %s",
+            oboe::convertToText(result)};
+
+    switch(mStream->getChannelCount())
+    {
+    case oboe::ChannelCount::Mono:
+        mDevice->FmtChans = DevFmtMono;
+        break;
+    case oboe::ChannelCount::Stereo:
+        mDevice->FmtChans = DevFmtStereo;
+        break;
+    /* Other potential configurations. Assume WFX channel order. */
+    case 4:
+        mDevice->FmtChans = DevFmtQuad;
+        break;
+    case 6:
+        mDevice->FmtChans = DevFmtX51Rear;
+        break;
+    case 7:
+        mDevice->FmtChans = DevFmtX61;
+        break;
+    case 8:
+        mDevice->FmtChans = DevFmtX71;
+        break;
+    default:
+        throw al::backend_exception{ALC_INVALID_DEVICE, "Got unhandled channel count: %d",
+            mStream->getChannelCount()};
+    }
+    SetDefaultWFXChannelOrder(mDevice);
+
+    switch(mStream->getFormat())
+    {
+    case oboe::AudioFormat::I16:
+        mDevice->FmtType = DevFmtShort;
+        break;
+    case oboe::AudioFormat::Float:
+        mDevice->FmtType = DevFmtFloat;
+        break;
+    case oboe::AudioFormat::Unspecified:
+    case oboe::AudioFormat::Invalid:
+        throw al::backend_exception{ALC_INVALID_DEVICE, "Got unhandled sample type: %d",
+            mStream->getFormat()};
+    }
+    mDevice->Frequency = static_cast<uint32_t>(mStream->getSampleRate());
+
+    /* Ensure the period size is no less than 10ms. It's possible for FramesPerBurst to be 0
+     * indicating variable updates, but OpenAL should have a reasonable minimum update size set.
+     */
+    mDevice->UpdateSize = maxu(mDevice->Frequency / 100,
+        static_cast<uint32_t>(mStream->getFramesPerBurst()));
+    mDevice->BufferSize = maxu(mDevice->UpdateSize * 2,
+        static_cast<uint32_t>(mStream->getBufferSizeInFrames()));
+
+    return true;
+}
+
+bool OboePlayback::start()
+{
+    oboe::Result result{mStream->start()};
+    if(result != oboe::Result::OK)
+        throw al::backend_exception{ALC_INVALID_DEVICE, "Failed to start stream: %s",
+            oboe::convertToText(result)};
+    return true;
+}
+
+void OboePlayback::stop()
+{
+    oboe::Result result{mStream->stop()};
+    if(result != oboe::Result::OK)
+        throw al::backend_exception{ALC_INVALID_DEVICE, "Failed to stop stream: %s",
+            oboe::convertToText(result)};
+}
+
+} // namespace
+
 bool OboeBackendFactory::init() { return true; }
 
-bool OboeBackendFactory::querySupport(BackendType /*type*/)
-{ return false; }
+bool OboeBackendFactory::querySupport(BackendType type)
+{ return type == BackendType::Playback; }
 
-std::string OboeBackendFactory::probe(BackendType /*type*/)
+std::string OboeBackendFactory::probe(BackendType type)
 {
+    switch(type)
+    {
+    case BackendType::Playback:
+        /* Includes null char. */
+        return std::string{device_name, sizeof(device_name)};
+    case BackendType::Capture:
+        break;
+    }
     return std::string{};
 }
 
-BackendPtr OboeBackendFactory::createBackend(ALCdevice* /*device*/, BackendType /*type*/)
+BackendPtr OboeBackendFactory::createBackend(ALCdevice *device, BackendType type)
 {
+    if(type == BackendType::Playback)
+        return BackendPtr{new OboePlayback{device}};
     return nullptr;
 }