public static WavFormat ReadWavFormat(BinaryReader inReader, out ushort inCbSize)
{
var inFormat = new WavFormat();
ExpectAscii(inReader, "fmt ");
var fmtLength = inReader.ReadUInt32();
inFormat.Format = (WavFormatCode)inReader.ReadUInt16();
inFormat.Channels = inReader.ReadUInt16();
inFormat.SampleRate = inReader.ReadUInt32();
var inByteRate = inReader.ReadUInt32();
var inBlockAlign = inReader.ReadUInt16();
inFormat.BitDepth = inReader.ReadUInt16();
inCbSize = (ushort)(fmtLength > 16 ? inReader.ReadUInt16() : 0);
inReader.BaseStream.Seek(inCbSize, SeekOrigin.Current); // Skip CB
if (inFormat.BlockAlign != inBlockAlign)
{
throw new FormatException(
string.Format("Inconsistent block alignment: {0} channels of {1} bits is not {2} bytes",
inFormat.Channels,
inFormat.BitDepth,
inBlockAlign));
}
if (inFormat.ByteRate != inByteRate)
{
throw new FormatException(
string.Format("Inconsistent sample rate: {0} channels of {1} bits at {2} KHz is not {3} KBps",
inFormat.Channels,
inFormat.BitDepth,
inFormat.SampleRate/1000,
inByteRate/1000));
}
return inFormat;
}
public static void Convert(
Stream inStream,
Stream outStream,
WavFormat outFormat)
{
using (var inReader = new BinaryReader(inStream))
{
var inFormat = new WavFormat();
// Read header
ExpectAscii(inReader, "RIFF");
var fileLength = inReader.ReadUInt32() + 8;
ExpectAscii(inReader, "WAVE");
ushort inCbSize;
inFormat = ReadWavFormat(inReader, out inCbSize);
ExpectAscii(inReader, "data");
inFormat.SetDataLength(inReader.ReadUInt32());
Console.WriteLine();
Console.WriteLine("Input file:");
Console.WriteLine(" Format: {0}", inFormat.Format);
Console.WriteLine(" Channels: {0}", inFormat.ChannelString);
Console.WriteLine(" Bit depth: {0} bit", inFormat.BitDepth);
Console.WriteLine(" Sample rate: {0} KHz", inFormat.SampleRate / 1000.0);
Console.WriteLine(" Bit rate: {0} Kbs", inFormat.ByteRate * 8 / 1000);
Console.WriteLine();
Console.WriteLine(" File length: {0} bytes", fileLength);
Console.WriteLine(" CB Size: {0} bytes", inCbSize);
Console.WriteLine(" Block align: {0} bytes", inFormat.BlockAlign);
Console.WriteLine(" Data: {0} samples", inFormat.Samples);
Console.WriteLine();
switch (inFormat.Format)
{
case WavFormatCode.Pcm:
case WavFormatCode.Ieee754:
case WavFormatCode.Extensible:
break;
default:
throw new FormatException(string.Format(
"File format {0} is not supported. Only PCM, Extensible, and IEEE 574", inFormat.Format));
}
outFormat.Samples = inFormat.Samples;
if (outStream != null)
{
using (var outWriter = new BinaryWriter(outStream))
{
Console.WriteLine("Writing output file");
var outFileLength = 44 + outFormat.DataLength;
// Write header
WriteAscii(outWriter, "RIFF");
outWriter.Write(outFileLength - 8);
WriteAscii(outWriter, "WAVE");
WriteAscii(outWriter, "fmt ");
outWriter.Write(16); // no CB
outWriter.Write((ushort)outFormat.Format);
outWriter.Write(outFormat.Channels);
outWriter.Write(outFormat.SampleRate);
outWriter.Write(outFormat.ByteRate);
outWriter.Write(outFormat.BlockAlign);
outWriter.Write(outFormat.BitDepth);
WriteAscii(outWriter, "data");
outWriter.Write(outFormat.DataLength);
MoveSamples(inReader, inFormat, outWriter, outFormat);
}
}
}
}
private static void WriteFrame(BinaryWriter outWriter, WavFormat outFormat, double[] frame)
{
switch (outFormat.Format)
{
case WavFormatCode.Pcm:
switch (outFormat.BitDepth)
{
case 8: WriteFrameI8(outWriter, frame); break;
case 16: WriteFrameI16(outWriter, frame); break;
case 32: WriteFrameI32(outWriter, frame); break;
default: throw new FormatException(string.Format(
"Output bit depth {0} is not supported", outFormat.BitDepth));
}
break;
case WavFormatCode.Ieee754:
switch (outFormat.BitDepth)
{
case 32: WriteFrameF32(outWriter, frame); break;
case 64: WriteFrameF64(outWriter, frame); break;
default: throw new FormatException(string.Format(
"Output IEEE bit depth {0} is not supported", outFormat.BitDepth));
}
break;
default:
throw new FormatException(string.Format(
"Output file format {0} is not supported", outFormat.Format));
}
}
private static double[] ReadFrame(BinaryReader inReader, WavFormat inFormat)
{
double[] frame;
switch (inFormat.Format)
{
case WavFormatCode.Pcm:
case WavFormatCode.Extensible:
switch (inFormat.BitDepth)
{
case 8: frame = ReadFrameI8(inReader, inFormat.Channels); break;
case 16: frame = ReadFrameI16(inReader, inFormat.Channels); break;
case 24: frame = ReadFrameI24(inReader, inFormat.Channels); break;
case 32: frame = ReadFrameI32(inReader, inFormat.Channels); break;
default: throw new FormatException(
"Input PCM bit depth " + inFormat.BitDepth + " is not supported");
}
break;
case WavFormatCode.Ieee754:
switch (inFormat.BitDepth)
{
case 32: frame = ReadFrameF32(inReader, inFormat.Channels); break;
case 64: frame = ReadFrameF64(inReader, inFormat.Channels); break;
default: throw new FormatException(
"Input IEEE bit depth " + inFormat.BitDepth + " is not supported");
}
break;
default:
throw new FormatException("Input file format " + inFormat.Format + " is not supported");
}
return frame;
}
private static void MoveSamples(
BinaryReader inReader, WavFormat inFormat,
BinaryWriter outWriter, WavFormat outFormat)
{
// For each frame that we read, we write as many frames as required for this slice of time
// (possibly zero if the output sample rate is lower than the input)
var lastInFrameTime = 0.0;
var lastOutFrameTime = 0.0;
var lastInFrame = new double[] {};
if (inReader.BaseStream.Position != inReader.BaseStream.Length)
{
lastInFrame = ReadFrame(inReader, inFormat);
lastInFrame = ApplyMatrix(lastInFrame, outFormat.Channels);
WriteFrame(outWriter, outFormat, lastInFrame);
}
var inDeltaTime = 1.0 / inFormat.SampleRate;
var outDeltaTime = 1.0 / outFormat.SampleRate;
while (inReader.BaseStream.Position != inReader.BaseStream.Length)
{
var thisInFrame = ReadFrame(inReader, inFormat);
var thisInFrameTime = lastInFrameTime + inDeltaTime;
thisInFrame = ApplyMatrix(thisInFrame, outFormat.Channels);
// Resample: output is interpolated from the last two frames from the source
for (var thisOutFrameTime = lastOutFrameTime + outDeltaTime;
thisOutFrameTime < thisInFrameTime;
thisOutFrameTime += outDeltaTime)
{
var ratio = (thisOutFrameTime - lastInFrameTime)/outDeltaTime;
var frame = lastInFrame.Zip(thisInFrame, (s1, s2) => ratio*s1 + (1.0 - ratio)*s2)
.ToArray();
WriteFrame(outWriter, outFormat, frame);
lastOutFrameTime = thisOutFrameTime;
}
lastInFrameTime = thisInFrameTime;
lastInFrame = thisInFrame;
}
}
