psemek/libs/audio/source/mixer.cpp

118 lines
2.2 KiB
C++

#include <psemek/audio/mixer.hpp>
#include <memory>
#include <vector>
#include <atomic>
namespace psemek::audio
{
namespace
{
struct channel_impl final
: mixer::channel
{
stream_ptr stream;
void stop() override;
bool is_stopped() const override;
};
void channel_impl::stop()
{
std::atomic_store(&stream, stream_ptr());
}
bool channel_impl::is_stopped() const
{
return std::atomic_load(&stream) != nullptr;
}
struct mixer_impl final
: mixer
, std::enable_shared_from_this<mixer_impl>
{
channel_ptr add(stream_ptr stream) override;
std::size_t read(float * data, std::size_t sample_count) override;
private:
std::vector<std::shared_ptr<channel_impl>> channels_;
std::vector<std::shared_ptr<channel_impl>> alive_channels_;
std::vector<float> buffer_;
std::mutex new_channels_mutex_;
std::vector<std::shared_ptr<channel_impl>> new_channels_;
};
mixer::channel_ptr mixer_impl::add(stream_ptr stream)
{
auto result = std::make_shared<channel_impl>();
result->stream = std::move(stream);
{
std::lock_guard lock{new_channels_mutex_};
new_channels_.push_back(result);
}
return result;
}
std::size_t mixer_impl::read(float * data, std::size_t sample_count)
{
{
std::vector<std::shared_ptr<channel_impl>> new_channels;
{
std::lock_guard lock{new_channels_mutex_};
new_channels = std::move(new_channels_);
}
for (auto & ch : new_channels)
channels_.push_back(std::move(ch));
}
std::fill(data, data + sample_count, 0.f);
buffer_.resize(sample_count);
for (auto & ch : channels_)
{
auto stream = std::atomic_load(&(ch->stream));
if (!stream)
continue;
auto read = stream->read(buffer_.data(), sample_count);
{
auto begin = buffer_.data();
auto end = begin + read;
auto dst = data;
for (; begin < end; )
*dst++ += *begin++;
}
if (read < sample_count)
{
ch->stop();
continue;
}
alive_channels_.push_back(std::move(ch));
}
std::swap(channels_, alive_channels_);
alive_channels_.clear();
return sample_count;
}
}
mixer_ptr make_mixer()
{
return std::make_shared<mixer_impl>();
}
}