/// <summary>
/// Reads the chunk describing the waveform format from the underlying stream.
/// </summary>
/// <returns>The waveform format.</returns>
private WaveformFormat ReadFormatChunk()
{
var chunkHeader = ReadChunkHeader(WaveformFileFormat.FormatChunkId);
if (chunkHeader.PayloadSize != WaveformFileFormat.FormatChunkPayloadSize)
{
throw new InvalidDataException("Unexpected format chunk size.");
}
var formatTag = _stream.ReadAsInt16();
if (formatTag != WaveformFileFormat.PcmFormatTag)
{
throw new InvalidDataException("Unsupported format.");
}
var channelsCount = _stream.ReadAsInt16();
var samplesPerSecond = _stream.ReadAsInt32();
var bytesPerSecond = _stream.ReadAsInt32();
var frameSize = _stream.ReadAsInt16();
var bitsPerSample = _stream.ReadAsInt16();
var sampleSize = WaveformFormat.GetSampleSize(bitsPerSample);
var expectedFrameSize = WaveformFormat.GetFrameSize(channelsCount, sampleSize);
var expectedBytesPerSecond = WaveformFormat.GetBytesPerSecond(frameSize, samplesPerSecond);
if (frameSize != expectedFrameSize ||
bytesPerSecond != expectedBytesPerSecond)
{
throw new InvalidDataException("Inconsistent sizes specified.");
}
return(new WaveformFormat(channelsCount, samplesPerSecond, bitsPerSample));
}
/// <summary>
/// Reads the chunk containing the waveform data from the underlying stream and returns
/// a streaming waveform. The underlying stream remains open until the object returned
/// here is disposed.
/// </summary>
/// <param name="format">The waveform format.</param>
/// <returns>A streaming waveform that should be disposed after use.</returns>
private StreamWaveform ReadDataChunk(WaveformFormat format)
{
var chunkHeader = ReadChunkHeader(WaveformFileFormat.DataChunkId);
var frameCount = chunkHeader.PayloadSize / format.FrameSize;
var frameStream = new FrameStream(_stream, format, frameCount);
return(new StreamWaveform(format, frameCount, frameStream));
}
/// <summary>
/// Writes the chunk describing the waveform format to the underlying stream.
/// </summary>
/// <param name="waveFormFormat">The waveform format.</param>
private void WriteFormatChunk(WaveformFormat waveFormFormat)
{
var chunkSize = WaveformFileFormat.FormatChunkPayloadSize;
var chunkHeader = new WaveformFileFormat.ChunkHeader(WaveformFileFormat.FormatChunkId, chunkSize);
WriteChunkHeader(chunkHeader);
_stream.WriteInt16(WaveformFileFormat.PcmFormatTag);
_stream.WriteInt16(waveFormFormat.ChannelsCount);
_stream.WriteInt32(waveFormFormat.SamplesPerSecond);
_stream.WriteInt32(waveFormFormat.BytesPerSecond);
_stream.WriteInt16(waveFormFormat.FrameSize);
_stream.WriteInt16(waveFormFormat.BitsPerSample);
}
/// <summary>
/// Initializes an instance of this class.
/// </summary>
/// <param name="format">The format of the waveform.</param>
public WaveformBase(WaveformFormat format)
{
Format = format;
}
/// <summary>
/// Initializes an instance of this class.
/// </summary>
/// <param name="format">The format of the waveform.</param>
/// <param name="frameCount">The number of frames within the waveform.</param>
/// <param name="frameStream">The stream providing the waveform's frames.</param>
public StreamWaveform(WaveformFormat format, int frameCount, IFrameStream frameStream)
: base(format)
{
_frameCount = frameCount;
_frameStream = frameStream;
}
/// <summary>
/// Initializes an instance of this class.
/// </summary>
/// <param name="format">The format of the waveform.</param>
/// <param name="frames">The frames within the waveform.</param>
public MemoryWaveform(WaveformFormat format, IEnumerable <IWaveformFrame> frames)
: base(format)
{
_frames = frames;
}
/// <summary>
/// Initializes an instance of this class.
/// </summary>
/// <param name="stream">The stream the frames are read from. The stream's
/// current position must be right before the frame bytes.</param>
/// <param name="format">The format of the waveform.</param>
/// <param name="frameCount">The number of frames within the waveform.</param>
public FrameStream(Stream stream, WaveformFormat format, int frameCount)
{
_stream = stream;
_format = format;
_frameCount = frameCount;
}
