soundloader_wav.cpp

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/*
 * This file is part of OpenTTD.
 * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
 * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
 */
 
#include "stdafx.h"
#include "core/bitmath_func.hpp"
#include "core/math_func.hpp"
#include "random_access_file_type.h"
#include "sound_type.h"
#include "soundloader_type.h"
 
#include "safeguards.h"
 
class SoundLoader_Wav : public SoundLoader {
public:
  SoundLoader_Wav() : SoundLoader("wav", "Wav sound loader", 0) {}
 
  static constexpr uint16_t DEFAULT_SAMPLE_RATE = 11025;
 
  bool Load(SoundEntry &sound, bool new_format, std::vector<uint8_t> &data) override
  {
    RandomAccessFile &file = *sound.file;
 
    /* Check RIFF/WAVE header. */
    if (file.ReadDword() != std::byteswap<uint32_t>('RIFF')) return false;
    file.ReadDword(); // Skip data size
    if (file.ReadDword() != std::byteswap<uint32_t>('WAVE')) return false;
 
    /* Read riff tags */
    for (;;) {
      uint32_t tag = file.ReadDword();
      uint32_t size = file.ReadDword();
 
      if (tag == std::byteswap<uint32_t>('fmt ')) {
        uint16_t format = file.ReadWord();
        if (format != 1) return false; // File must be uncompressed PCM
 
        sound.channels = file.ReadWord();
        if (sound.channels != 1) return false; // File must be mono.
 
        sound.rate = file.ReadDword();
        if (!new_format) sound.rate = DEFAULT_SAMPLE_RATE; // All old samples should be played at 11025 Hz.
 
        file.ReadDword(); // avg bytes per second
        file.ReadWord();  // alignment
 
        sound.bits_per_sample = file.ReadWord();
        if (sound.bits_per_sample != 8 && sound.bits_per_sample != 16) return false; // File must be 8 or 16 BPS.
 
        /* We've read 16 bytes of this chunk, we can skip anything extra. */
        size -= 16;
      } else if (tag == std::byteswap<uint32_t>('data')) {
        uint align = sound.channels * sound.bits_per_sample / 8;
        if (Align(size, align) != size) return false; // Ensure length is aligned correctly for channels and BPS.
 
        if (size == 0) return true; // No need to continue.
 
        /* Allocate an extra sample to ensure the runtime resampler doesn't go out of bounds. */
        data.reserve(size + align);
        data.resize(size);
 
        file.ReadBlock(std::data(data), size);
 
        switch (sound.bits_per_sample) {
          case 8:
            /* Convert 8-bit samples from unsigned to signed. */
            for (auto &sample : data) {
              sample = sample - 128;
            }
            break;
 
          case 16:
            /* 16-bit samples in wav files are little endian, and may need to be converted to native endian. */
            if constexpr (std::endian::native != std::endian::little) {
              for (auto it = std::begin(data); it != std::end(data); /* nothing */) {
                std::swap(*it++, *it++);
              }
            }
            break;
 
          default: NOT_REACHED();
        }
 
        return true;
      }
 
      /* Skip rest of chunk. */
      if (size > 0) file.SkipBytes(size);
    }
 
    return false;
  }
};
 
static SoundLoader_Wav s_sound_loader_wav;