psemek/libs/audio/source/track_mp3.cpp

143 lines
3.2 KiB
C++

#include <psemek/audio/track.hpp>
#include <psemek/audio/resampler.hpp>
#include <psemek/audio/constants.hpp>
#include <psemek/audio/minimp3/options.h>
#include <psemek/audio/minimp3/minimp3.h>
#include <atomic>
namespace psemek::audio
{
namespace
{
struct mp3_data_holder
{
std::vector<char> storage;
util::span<char const> data;
mp3_data_holder(std::vector<char> storage)
: storage(std::move(storage))
, data(this->storage)
{}
mp3_data_holder(util::span<char const> data)
: data(data)
{}
};
struct mp3_stream_impl
: stream
{
mp3_stream_impl(std::shared_ptr<mp3_data_holder> data)
: data_(std::move(data))
, source_buffer_(MINIMP3_MAX_SAMPLES_PER_FRAME)
{
mp3dec_init(&decoder_);
}
std::optional<std::size_t> length() const override
{
return std::nullopt;
}
std::size_t read(util::span<float> samples) override
{
auto input = reinterpret_cast<std::uint8_t const *>(data_->data.data());
std::size_t count = 0;
while (count < samples.size())
{
if (resampler_pos_ < resampler_.result().size())
{
std::size_t size = std::min(resampler_.result().size() - resampler_pos_, samples.size() - count);
std::copy(resampler_.result().data() + resampler_pos_, resampler_.result().data() + resampler_pos_ + size, samples.begin() + count);
resampler_pos_ += size;
count += size;
}
else
{
mp3dec_frame_info_t frame_info;
auto source_buffer_size = mp3dec_decode_frame(&decoder_, input + read_bytes_, data_->data.size() - read_bytes_, source_buffer_.data(), &frame_info);
resampler_pos_ = 0;
read_bytes_ += frame_info.frame_bytes;
if (frame_info.frame_bytes == 0)
break;
if (frame_info.channels == 1)
{
for (std::size_t i = source_buffer_size * 2; i > 0;)
{
i -= 2;
source_buffer_[i + 0] = source_buffer_[i / 2];
source_buffer_[i + 1] = source_buffer_[i / 2];
}
}
source_buffer_size *= 2;
resampler_.ratio(static_cast<float>(frequency) / frame_info.hz);
resampler_.feed({source_buffer_.data(), source_buffer_.data() + source_buffer_size});
}
}
played_.fetch_add(count);
return count;
}
std::size_t played() const override
{
return played_.load();
}
private:
std::shared_ptr<mp3_data_holder> data_;
std::size_t read_bytes_{0};
mp3dec_t decoder_;
std::vector<float> source_buffer_;
resampler resampler_;
std::size_t resampler_pos_{0};
std::atomic<std::size_t> played_{0};
};
struct mp3_track_impl
: track
{
mp3_track_impl(std::shared_ptr<mp3_data_holder> data)
: data_(std::move(data))
{}
stream_ptr stream() const override
{
return std::make_shared<mp3_stream_impl>(data_);
}
std::optional<std::size_t> length() const override
{
return std::nullopt;
}
private:
std::shared_ptr<mp3_data_holder> data_;
};
}
track_ptr load_mp3(util::span<char const> data)
{
return std::make_shared<mp3_track_impl>(std::make_shared<mp3_data_holder>(data));
}
track_ptr load_mp3(std::vector<char> data)
{
return std::make_shared<mp3_track_impl>(std::make_shared<mp3_data_holder>(std::move(data)));
}
}