Handling WAVE format in D Raw. This program works as $ ffmpeg -i filename -f s16le -ac 2 -acodec pcm_s16le -ar 44100 filename.pcm

wave.d

import std.stdio;

struct ChunkHead {
  char[4] id;
  uint size;
}

struct RiffChunk {
  ChunkHead head;
  char[4] format;
}

struct WaveFileFormat {
  ushort audioFormat,
         channels;
  uint   samplePerSecond,
         bytesPerSecond;
  ushort blockAlign,
         bitsPerSample;
}

struct WaveFormatChunk {
  ChunkHead chunk;
  WaveFileFormat format;
}

auto min(M, N)(M m, N n) {
  return m > n ? n : m;
}

//This program works as $ ffmpeg -i filename -f s16le -ac 2 -acodec pcm_s16le -ar 44100 filename.pcm
void main() {
  string filename = "filename.wav";
  
  auto file = File(filename, "rb");
  ubyte[] buf;
  buf.length = file.size;
  file.rawRead(buf);

  size_t b = 0,
         e = RiffChunk.sizeof;

  RiffChunk* riff = cast(RiffChunk*)buf[b..e];

  WaveFileFormat* format;
  ubyte[] pcm;

  if(riff.head.id != "RIFF") {
    writeln("Invalid WAV format was given");
    return;
  } 

  if (riff.format != "WAVE") {
    writeln("Invalid RIFF chunk format. Given file is not WAVE");
    return;
  }

  ChunkHead* chunk;

  b = e;

  while (b < buf.length) {
    e = b + ChunkHead.sizeof;
    chunk = cast(ChunkHead*)buf[b..e];

    if (chunk.size < 0) {
      writeln("ERROR! Invalid chunk size");
      return;
    }

    b = e;

    if (chunk.id == "fmt ") {
      e = b + min(chunk.size, WaveFormatChunk.sizeof);
      format = cast(WaveFileFormat*)buf[b..e];

      b = e;
    } else if (chunk.id == "data") {
      pcm.length = chunk.size;

      e = b + chunk.size;
      pcm = buf[b..e];

      b = e;
    } else {//skip others chunks
      b = e + chunk.size;
    }
  }

  writeln("FORMAT INFORMATIONS");
  writeln("audioFormat: ", format.audioFormat);
  writeln("channels: ", format.channels);
  writeln("samplePerSecond: ", format.samplePerSecond);
  writeln("bytesPerSecond: ", format.bytesPerSecond);
  writeln("blockAlign: ", format.blockAlign);
  writeln("bitsPerSample: ", format.bitsPerSample);

  //Save raw PCM data to filename.pcm
  File(filename ~ ".pcm", "wb").rawWrite(pcm);
}