Duckstation/src/common/wav_writer.cpp

#include "wav_writer.h"
#include "file_system.h"
#include "log.h"
Log_SetChannel(WAVWriter);

#pragma pack(push, 1)
struct WAV_HEADER
{
  u32 chunk_id; // RIFF
  u32 chunk_size;
  u32 format; // WAVE

  struct FormatChunk
  {
    u32 chunk_id; // "fmt "
    u32 chunk_size;
    u16 audio_format; // pcm = 1
    u16 num_channels;
    u32 sample_rate;
    u32 byte_rate;
    u16 block_align;
    u16 bits_per_sample;
  } fmt_chunk;

  struct DataChunkHeader
  {
    u32 chunk_id; // "data "
    u32 chunk_size;
  } data_chunk_header;
};
#pragma pack(pop)

namespace Common {

WAVWriter::WAVWriter() = default;

WAVWriter::~WAVWriter()
{
  if (IsOpen())
    Close();
}

bool WAVWriter::Open(const char* filename, u32 sample_rate, u32 num_channels)
{
  if (IsOpen())
    Close();

  m_file = FileSystem::OpenCFile(filename, "wb");
  if (!m_file)
    return false;

  m_sample_rate = sample_rate;
  m_num_channels = num_channels;

  if (!WriteHeader())
  {
    Log_ErrorPrintf("Failed to write header to file");
    m_sample_rate = 0;
    m_num_channels = 0;
    std::fclose(m_file);
    m_file = nullptr;
    return false;
  }

  return true;
}

void WAVWriter::Close()
{
  if (!IsOpen())
    return;

  if (std::fseek(m_file, 0, SEEK_SET) != 0 || !WriteHeader())
    Log_ErrorPrintf("Failed to re-write header on file, file may be unplayable");

  std::fclose(m_file);
  m_file = nullptr;
  m_sample_rate = 0;
  m_num_channels = 0;
  m_num_frames = 0;
}

void WAVWriter::WriteFrames(const s16* samples, u32 num_frames)
{
  const u32 num_frames_written =
    static_cast<u32>(std::fwrite(samples, sizeof(s16) * m_num_channels, num_frames, m_file));
  if (num_frames_written != num_frames)
    Log_ErrorPrintf("Only wrote %u of %u frames to output file", num_frames_written);

  m_num_frames += num_frames_written;
}

bool WAVWriter::WriteHeader()
{
  const u32 data_size = sizeof(SampleType) * m_num_channels * m_num_frames;

  WAV_HEADER header = {};
  header.chunk_id = 0x46464952; // 0x52494646
  header.chunk_size = sizeof(WAV_HEADER) - 8 + data_size;
  header.format = 0x45564157;             // 0x57415645
  header.fmt_chunk.chunk_id = 0x20746d66; // 0x666d7420
  header.fmt_chunk.chunk_size = sizeof(header.fmt_chunk) - 8;
  header.fmt_chunk.audio_format = 1;
  header.fmt_chunk.num_channels = static_cast<u16>(m_num_channels);
  header.fmt_chunk.sample_rate = m_sample_rate;
  header.fmt_chunk.byte_rate = m_sample_rate * m_num_channels * sizeof(SampleType);
  header.fmt_chunk.block_align = static_cast<u16>(m_num_channels * sizeof(SampleType));
  header.fmt_chunk.bits_per_sample = 16;
  header.data_chunk_header.chunk_id = 0x61746164; // 0x64617461
  header.data_chunk_header.chunk_size = data_size;

  return (std::fwrite(&header, sizeof(header), 1, m_file) == 1);
}

} // namespace Common