audio_core: Implement a cubeb audio sink

CMakeLists.txt

@@ -18,6 +18,8 @@ CMAKE_DEPENDENT_OPTION(CITRA_USE_BUNDLED_QT "Download bundled Qt binaries" ON "E
 
 option(ENABLE_WEB_SERVICE "Enable web services (telemetry, etc.)" ON)
 
+option(ENABLE_CUBEB "Enables the cubeb audio backend" ON)
+
 if(NOT EXISTS ${CMAKE_SOURCE_DIR}/.git/hooks/pre-commit)
     message(STATUS "Copying pre-commit hook")
     file(COPY hooks/pre-commit

externals/CMakeLists.txt

@@ -77,3 +77,8 @@ if (ENABLE_WEB_SERVICE)
     add_library(json-headers INTERFACE)
     target_include_directories(json-headers INTERFACE ./json)
 endif()
+
+# Cubeb
+if(ENABLE_CUBEB)
+    add_subdirectory(cubeb)
+endif()

src/audio_core/CMakeLists.txt

@@ -24,6 +24,7 @@ add_library(audio_core STATIC
     time_stretch.h
 
     $<$<BOOL:${SDL2_FOUND}>:sdl2_sink.cpp sdl2_sink.h>
+    $<$<BOOL:${ENABLE_CUBEB}>:cubeb_sink.cpp cubeb_sink.h>
 )
 
 create_target_directory_groups(audio_core)
@@ -35,3 +36,7 @@ if(SDL2_FOUND)
     target_link_libraries(audio_core PRIVATE SDL2)
     target_compile_definitions(audio_core PRIVATE HAVE_SDL2)
 endif()
+
+if(ENABLE_CUBEB)
+    target_link_libraries(audio_core PRIVATE cubeb)
+endif()

src/audio_core/cubeb_sink.cpp

@@ -0,0 +1,146 @@
+// Copyright 2018 Citra Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#include <vector>
+#include <cubeb/cubeb.h>
+#include "audio_core/audio_types.h"
+#include "audio_core/cubeb_sink.h"
+#include "common/logging/log.h"
+#include "core/settings.h"
+
+namespace AudioCore {
+
+struct CubebSink::Impl {
+    unsigned int sample_rate = 0;
+
+    cubeb* ctx = nullptr;
+    cubeb_stream* stream = nullptr;
+
+    std::vector<s16> queue;
+
+    static long DataCallback(cubeb_stream* stream, void* user_data, const void* input_buffer,
+                             void* output_buffer, long num_frames);
+    static void StateCallback(cubeb_stream* stream, void* user_data, cubeb_state state);
+};
+
+CubebSink::CubebSink() : impl(std::make_unique<Impl>()) {
+    if (cubeb_init(&impl->ctx, "Citra", nullptr) != CUBEB_OK) {
+        NGLOG_CRITICAL(Audio_Sink, "cubeb_init failed");
+        return;
+    }
+
+    const char* target_device_name = nullptr;
+    cubeb_devid output_device = nullptr;
+
+    cubeb_stream_params params;
+    params.rate = native_sample_rate;
+    params.channels = 2;
+    params.format = CUBEB_SAMPLE_S16NE;
+    params.layout = CUBEB_LAYOUT_STEREO;
+
+    impl->sample_rate = native_sample_rate;
+
+    u32 minimum_latency = 0;
+    if (cubeb_get_min_latency(impl->ctx, &params, &minimum_latency) != CUBEB_OK)
+        NGLOG_CRITICAL(Audio_Sink, "Error getting minimum latency");
+
+    cubeb_device_collection collection;
+    if (cubeb_enumerate_devices(impl->ctx, CUBEB_DEVICE_TYPE_OUTPUT, &collection) != CUBEB_OK) {
+        NGLOG_WARNING(Audio_Sink, "Audio output device enumeration not supported");
+    } else {
+        if (collection.count >= 1 && Settings::values.audio_device_id != "auto" &&
+            !Settings::values.audio_device_id.empty()) {
+            target_device_name = Settings::values.audio_device_id.c_str();
+        }
+
+        for (size_t i = 0; i < collection.count; i++) {
+            const cubeb_device_info& device = collection.device[i];
+            device_list.emplace_back(device.friendly_name);
+
+            if (target_device_name && strcmp(target_device_name, device.friendly_name) == 0) {
+                output_device = device.devid;
+            }
+        }
+
+        cubeb_device_collection_destroy(impl->ctx, &collection);
+    }
+
+    if (cubeb_stream_init(impl->ctx, &impl->stream, "Citra Audio Output", nullptr, nullptr,
+                          output_device, &params, std::max(512u, minimum_latency),
+                          &Impl::DataCallback, &Impl::StateCallback, impl.get()) != CUBEB_OK) {
+        NGLOG_CRITICAL(Audio_Sink, "Error initializing cubeb stream");
+        return;
+    }
+
+    if (cubeb_stream_start(impl->stream) != CUBEB_OK) {
+        NGLOG_CRITICAL(Audio_Sink, "Error starting cubeb stream");
+        return;
+    }
+}
+
+CubebSink::~CubebSink() {
+    if (!impl->ctx)
+        return;
+
+    if (cubeb_stream_stop(impl->stream) != CUBEB_OK) {
+        NGLOG_CRITICAL(Audio_Sink, "Error stopping cubeb stream");
+    }
+
+    cubeb_stream_destroy(impl->stream);
+    cubeb_destroy(impl->ctx);
+}
+
+unsigned int CubebSink::GetNativeSampleRate() const {
+    if (!impl->ctx)
+        return native_sample_rate;
+
+    return impl->sample_rate;
+}
+
+std::vector<std::string> CubebSink::GetDeviceList() const {
+    return device_list;
+}
+
+void CubebSink::EnqueueSamples(const s16* samples, size_t sample_count) {
+    if (!impl->ctx)
+        return;
+
+    impl->queue.reserve(impl->queue.size() + sample_count * 2);
+    std::copy(samples, samples + sample_count * 2, std::back_inserter(impl->queue));
+}
+
+size_t CubebSink::SamplesInQueue() const {
+    if (!impl->ctx)
+        return 0;
+
+    return impl->queue.size() / 2;
+}
+
+void CubebSink::SetDevice(int device_id) {}
+
+long CubebSink::Impl::DataCallback(cubeb_stream* stream, void* user_data, const void* input_buffer,
+                                   void* output_buffer, long num_frames) {
+    Impl* impl = static_cast<Impl*>(user_data);
+    u8* buffer = reinterpret_cast<u8*>(output_buffer);
+
+    if (!impl)
+        return 0;
+
+    size_t frames_to_write = std::min(impl->queue.size() / 2, static_cast<size_t>(num_frames));
+
+    memcpy(buffer, impl->queue.data(), frames_to_write * sizeof(s16) * 2);
+    impl->queue.erase(impl->queue.begin(), impl->queue.begin() + frames_to_write * 2);
+
+    if (frames_to_write < num_frames) {
+        // Fill the rest of the frames with silence
+        memset(buffer + frames_to_write * sizeof(s16) * 2, 0,
+               (num_frames - frames_to_write) * sizeof(s16) * 2);
+    }
+
+    return num_frames;
+}
+
+void CubebSink::Impl::StateCallback(cubeb_stream* stream, void* user_data, cubeb_state state) {}
+
+} // namespace AudioCore

src/audio_core/cubeb_sink.h

@@ -0,0 +1,34 @@
+// Copyright 2018 Citra Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include <cstddef>
+#include <memory>
+#include "audio_core/sink.h"
+
+namespace AudioCore {
+
+class CubebSink final : public Sink {
+public:
+    CubebSink();
+    ~CubebSink() override;
+
+    unsigned int GetNativeSampleRate() const override;
+
+    void EnqueueSamples(const s16* samples, size_t sample_count) override;
+
+    size_t SamplesInQueue() const override;
+
+    std::vector<std::string> GetDeviceList() const override;
+    void SetDevice(int device_id) override;
+
+private:
+    struct Impl;
+    std::unique_ptr<Impl> impl;
+    int device_id;
+    std::vector<std::string> device_list;
+};
+
+} // namespace AudioCore

src/audio_core/sink_details.cpp

@@ -11,12 +11,14 @@
 #ifdef HAVE_SDL2
 #include "audio_core/sdl2_sink.h"
 #endif
+#include "audio_core/cubeb_sink.h"
 #include "common/logging/log.h"
 
 namespace AudioCore {
 
 // g_sink_details is ordered in terms of desirability, with the best choice at the top.
 const std::vector<SinkDetails> g_sink_details = {
+    {"cubeb", []() { return std::make_unique<CubebSink>(); }},
 #ifdef HAVE_SDL2
     {"sdl2", []() { return std::make_unique<SDL2Sink>(); }},
 #endif