tangara-fw/src/codecs/include/mad.hpp

/*
 * Copyright 2023 jacqueline <me@jacqueline.id.au>
 *
 * SPDX-License-Identifier: GPL-3.0-only
 */

#pragma once

#include <cstddef>
#include <cstdint>
#include <optional>
#include <string>
#include <utility>

#include "mad.h"
#include "span.hpp"

#include "codec.hpp"

namespace codecs {

class MadMp3Decoder : public ICodec {
 public:
  MadMp3Decoder();
  ~MadMp3Decoder();

  /*
   * Returns the output format for the next frame in the stream. MP3 streams
   * may represent multiple distinct tracks, with different bitrates, and so we
   * handle the stream only on a frame-by-frame basis.
   */
  auto BeginStream(cpp::span<const std::byte>) -> Result<OutputFormat> override;

  /*
   * Writes samples for the current frame.
   */
  auto ContinueStream(cpp::span<const std::byte> input,
                      cpp::span<std::byte> output)
      -> Result<OutputInfo> override;

  auto SeekStream(cpp::span<const std::byte> input, std::size_t target_sample)
      -> Result<void> override;

 private:
  auto GetVbrLength(const mad_header& header) -> std::optional<uint32_t>;

  mad_stream stream_;
  mad_frame frame_;
  mad_synth synth_;

  int current_sample_;

  auto GetBytesUsed(std::size_t) -> std::size_t;
};

}  // namespace codecs