/// <summary>
/// FLAC Write Call Back - libFlac notifies back on a frame that was read from the source file and written as a frame
/// </summary>
/// <param name="context"></param>
/// <param name="frame"></param>
/// <param name="buffer"></param>
/// <param name="clientData"></param>
private void FLAC_WriteCallback(IntPtr context, IntPtr frame, IntPtr buffer, IntPtr clientData)
{
// Read the FLAC Frame into a memory samples buffer (m_flacSamples)
LibFLACSharp.FlacFrame flacFrame = (LibFLACSharp.FlacFrame)Marshal.PtrToStructure(frame, typeof(LibFLACSharp.FlacFrame));
if (m_flacSamples == null)
{
// First time - Create Flac sample buffer
m_samplesPerChannel = flacFrame.Header.BlockSize;
m_flacSamples = new int[m_samplesPerChannel * m_flacStreamInfo.Channels];
m_flacSampleIndex = 0;
}
// Iterate on all channels, copy the unmanaged channel bits (samples) to the a managed samples array
for (int inputChannel = 0; inputChannel < m_flacStreamInfo.Channels; inputChannel++)
{
// Get pointer to channel bits, for the current channel
IntPtr pChannelBits = Marshal.ReadIntPtr(buffer, inputChannel * IntPtr.Size);
// Copy the unmanaged bits to managed memory
Marshal.Copy(pChannelBits, m_flacSamples, inputChannel * m_samplesPerChannel, m_samplesPerChannel);
}
lock (m_repositionLock)
{
// Keep the current sample number for reporting purposes (See: Position property of FlacFileReader)
m_lastSampleNumber = flacFrame.Header.FrameOrSampleNumber;
if (m_repositionRequested)
{
m_repositionRequested = false;
FLACCheck(LibFLACSharp.FLAC__stream_decoder_seek_absolute(m_decoderContext, m_flacReposition), "Could not seek absolute: " + m_flacReposition);
}
}
}
/// <summary>
/// Disposes this WaveStream
/// </summary>
protected override void Dispose(bool disposing)
{
if (disposing)
{
if (m_decoderContext != IntPtr.Zero)
{
FLACCheck(
LibFLACSharp.FLAC__stream_decoder_finish(m_decoderContext),
"finalize stream decoder");
FLACCheck(
LibFLACSharp.FLAC__stream_decoder_delete(m_decoderContext),
"dispose of stream decoder instance");
m_decoderContext = IntPtr.Zero;
}
if (m_stream != null)
{
m_stream.Close();
m_stream.Dispose();
m_stream = null;
}
if (m_reader != null)
{
m_reader.Close();
m_reader = null;
}
}
base.Dispose(disposing);
}
/// <summary>Constructor - Supports opening a FLAC file</summary>
public FLACFileReader(string flacFileName)
{
Console.WriteLine("FLACFileReader: " + flacFileName);
// Open the flac file for reading through a binary reader
m_stream = File.OpenRead(flacFileName);
m_reader = new BinaryReader(m_stream);
// Create the FLAC decoder
m_decoderContext = LibFLACSharp.FLAC__stream_decoder_new();
if (m_decoderContext == IntPtr.Zero)
{
throw new ApplicationException("FLAC: Could not initialize stream decoder!");
}
// Create call back delegates
m_writeCallback = new LibFLACSharp.Decoder_WriteCallback(FLAC_WriteCallback);
m_metadataCallback = new LibFLACSharp.Decoder_MetadataCallback(FLAC_MetadataCallback);
m_errorCallback = new LibFLACSharp.Decoder_ErrorCallback(FLAC_ErrorCallback);
// Initialize the FLAC decoder
if (LibFLACSharp.FLAC__stream_decoder_init_file(m_decoderContext,
flacFileName, m_writeCallback, m_metadataCallback, m_errorCallback,
IntPtr.Zero) != 0)
{
throw new ApplicationException("FLAC: Could not open stream for reading!");
}
// Process the meta-data (but not the audio frames) so we can prepare the NAudio wave format
FLACCheck(
LibFLACSharp.FLAC__stream_decoder_process_until_end_of_metadata(m_decoderContext),
"Could not process until end of metadata");
// Initialize NAudio wave format
m_waveFormat = new WaveFormat(m_flacStreamInfo.SampleRate, m_flacStreamInfo.BitsPerSample, m_flacStreamInfo.Channels);
Console.WriteLine("Total FLAC Samples: {0}", LibFLACSharp.FLAC__stream_decoder_get_total_samples(m_decoderContext));
}
/// <summary>
/// Reads decompressed PCM data from our FLAC file into the NAudio playback sample buffer
/// </summary>
/// <remarks>
/// 1. The original code did not stop on end of stream. tomislavtustonic applied a fix using FLAC__stream_decoder_get_state. <seealso cref="https://code.google.com/p/practicesharp/issues/detail?id=14"/>
/// </remarks>
public override int Read(byte[] playbackSampleBuffer, int offset, int numBytes)
{
int flacBytesCopied = 0;
m_NAudioSampleBuffer = playbackSampleBuffer;
m_playbackBufferOffset = offset;
lock (m_repositionLock)
{
// If there are still samples in the flac buffer, use them first before reading the next FLAC frame
if (m_flacSampleIndex > 0)
{
flacBytesCopied = CopyFlacBufferToNAudioBuffer();
}
}
var decoderState = LibFLACSharp.FLAC__stream_decoder_get_state(m_decoderContext);
// Keep reading flac packets until enough bytes have been copied
while (flacBytesCopied < numBytes)
{
// Read the next PCM bytes from the FLAC File into the sample buffer
FLACCheck(
LibFLACSharp.FLAC__stream_decoder_process_single(m_decoderContext),
"process single");
decoderState = LibFLACSharp.FLAC__stream_decoder_get_state(m_decoderContext);
if (decoderState == LibFLACSharp.StreamDecoderState.EndOfStream)
{
break;
}
else
{
flacBytesCopied += CopyFlacBufferToNAudioBuffer();
}
}
return(flacBytesCopied);
}
/// <summary>
/// FLAC Error Call Back - libFlac notifies about a decoding error
/// </summary>
/// <param name="context"></param>
/// <param name="status"></param>
/// <param name="userData"></param>
private void FLAC_ErrorCallback(IntPtr context, LibFLACSharp.DecodeError status, IntPtr userData)
{
throw new ApplicationException(string.Format("FLAC: Could not decode frame: {0}!", status));
}
