citra/src/audio_core/stream.cpp

// Copyright 2018 yuzu Emulator Project
// Licensed under GPLv2 or any later version
// Refer to the license.txt file included.

#include <algorithm>
#include <cmath>

#include "audio_core/sink.h"
#include "audio_core/sink_details.h"
#include "audio_core/stream.h"
#include "common/assert.h"
#include "common/logging/log.h"
#include "core/core_timing.h"
#include "core/core_timing_util.h"
#include "core/settings.h"

namespace AudioCore {

constexpr size_t MaxAudioBufferCount{32};

u32 Stream::GetNumChannels() const {
    switch (format) {
    case Format::Mono16:
        return 1;
    case Format::Stereo16:
        return 2;
    case Format::Multi51Channel16:
        return 6;
    }
    LOG_CRITICAL(Audio, "Unimplemented format={}", static_cast<u32>(format));
    UNREACHABLE();
    return {};
}

u32 Stream::GetSampleSize() const {
    return GetNumChannels() * 2;
}

Stream::Stream(u32 sample_rate, Format format, ReleaseCallback&& release_callback,
               SinkStream& sink_stream)
    : sample_rate{sample_rate}, format{format}, release_callback{std::move(release_callback)},
      sink_stream{sink_stream} {

    release_event = CoreTiming::RegisterEvent(
        "Stream::Release", [this](u64 userdata, int cycles_late) { ReleaseActiveBuffer(); });
}

void Stream::Play() {
    state = State::Playing;
    PlayNextBuffer();
}

void Stream::Stop() {
    ASSERT_MSG(false, "Unimplemented");
}

s64 Stream::GetBufferReleaseCycles(const Buffer& buffer) const {
    const size_t num_samples{buffer.GetData().size() / GetSampleSize()};
    return CoreTiming::usToCycles((static_cast<u64>(num_samples) * 1000000) / sample_rate);
}

static std::vector<s16> GetVolumeAdjustedSamples(const std::vector<u8>& data) {
    std::vector<s16> samples(data.size() / sizeof(s16));
    std::memcpy(samples.data(), data.data(), data.size());
    const float volume{std::clamp(Settings::values.volume, 0.0f, 1.0f)};

    if (volume == 1.0f) {
        return samples;
    }

    // Implementation of a volume slider with a dynamic range of 60 dB
    const float volume_scale_factor{std::exp(6.90775f * volume) * 0.001f};
    for (auto& sample : samples) {
        sample = static_cast<s16>(sample * volume_scale_factor);
    }

    return samples;
}

void Stream::PlayNextBuffer() {
    if (!IsPlaying()) {
        // Ensure we are in playing state before playing the next buffer
        return;
    }

    if (active_buffer) {
        // Do not queue a new buffer if we are already playing a buffer
        return;
    }

    if (queued_buffers.empty()) {
        // No queued buffers - we are effectively paused
        return;
    }

    active_buffer = queued_buffers.front();
    queued_buffers.pop();

    const size_t sample_count{active_buffer->GetData().size() / GetSampleSize()};
    sink_stream.EnqueueSamples(
        GetNumChannels(), GetVolumeAdjustedSamples(active_buffer->GetData()).data(), sample_count);

    CoreTiming::ScheduleEventThreadsafe(GetBufferReleaseCycles(*active_buffer), release_event, {});
}

void Stream::ReleaseActiveBuffer() {
    released_buffers.push(std::move(active_buffer));
    release_callback();
    PlayNextBuffer();
}

bool Stream::QueueBuffer(BufferPtr&& buffer) {
    if (queued_buffers.size() < MaxAudioBufferCount) {
        queued_buffers.push(std::move(buffer));
        PlayNextBuffer();
        return true;
    }
    return false;
}

bool Stream::ContainsBuffer(Buffer::Tag tag) const {
    ASSERT_MSG(false, "Unimplemented");
    return {};
}

std::vector<Buffer::Tag> Stream::GetTagsAndReleaseBuffers(size_t max_count) {
    std::vector<Buffer::Tag> tags;
    for (size_t count = 0; count < max_count && !released_buffers.empty(); ++count) {
        tags.push_back(released_buffers.front()->GetTag());
        released_buffers.pop();
    }
    return tags;
}

} // namespace AudioCore