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SpeexDecoder.cs
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SpeexDecoder.cs
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//
// Copyright (C) 2009-2010 Christoph Fröschl
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions
// are met:
//
// - Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
//
// - Redistributions in binary form must reproduce the above copyright
// notice, this list of conditions and the following disclaimer in the
// documentation and/or other materials provided with the distribution.
//
// - Neither the name of the Xiph.org Foundation nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR
// CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
// EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
// PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
// LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
// NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
//
using System;
namespace NSpeex
{
/// <summary>
/// NSpeex Decoder class. This class decodes the given speex frames into
/// PCM 16bit samples.
/// </summary>
public class SpeexDecoder
{
private readonly int sampleRate;
private float[] decodedData;
private readonly Bits bits;
private readonly IDecoder decoder;
private readonly int frameSize;
/// <summary>
/// Constructor
/// <param name="mode">The mode of the decoder.</param>
/// <param name="enhanced">Whether to enable perceptual enhancement or not.</param>
/// </summary>
public SpeexDecoder(BandMode mode, bool enhanced = true)
{
bits = new Bits();
switch (mode)
{
case BandMode.Narrow:
decoder = new NbDecoder();
sampleRate = 8000;
break;
// Wideband
case BandMode.Wide:
decoder = new SbDecoder(false);
sampleRate = 16000;
break;
case BandMode.UltraWide:
decoder = new SbDecoder(true);
sampleRate = 32000;
break;
// */
default:
decoder = new NbDecoder();
sampleRate = 8000;
break;
}
/* initialize the speex decoder */
decoder.PerceptualEnhancement = enhanced;
/* set decoder format and properties */
frameSize = decoder.FrameSize;
decodedData = new float[sampleRate * 2]; // init buffer to 1 second
}
/// <summary>
/// The frame size indicates the samples which are packed in a single Speex frame.
/// </summary>
public int FrameSize
{
get
{
return decoder.FrameSize;
}
}
/// <summary>
/// The sampling rate in samples per second
/// </summary>
public int SampleRate
{
get
{
return sampleRate;
}
}
/// <summary>
/// Decodes the given encoded data.
/// </summary>
/// <param name="inData">The encoded data. Can be multiple frames.</param>
/// <param name="inOffset">Start offset where to read the encoded data from.</param>
/// <param name="inCount">The number of bytes to decode.</param>
/// <param name="outData">The output of the decoded data in samples.</param>
/// <param name="outOffset">Start offset where to start writing the decoded samples from.</param>
/// <param name="lostFrame">Indicates if we are decoding a lost frame. Alternatively the <paramref name="inData"/> parameter can be <value>null</value>.</param>
/// <returns>The number of samples decoded.</returns>
public int Decode(byte[] inData, int inOffset, int inCount, short[] outData, int outOffset, bool lostFrame)
{
if (decodedData.Length < outData.Length * 2)
{
// resize the decoded data buffer
decodedData = new float[outData.Length * 2];
}
if (lostFrame || inData == null)
{
decoder.Decode(null, decodedData);
for (int i = 0; i < frameSize; i++, outOffset++)
{
outData[outOffset] = ConvertToShort(decodedData[i]);
}
return frameSize;
}
bits.ReadFrom(inData, inOffset, inCount);
int samplesDecoded = 0;
while (decoder.Decode(bits, decodedData) == 0)
{
for (int i = 0; i < frameSize; i++, outOffset++)
{
outData[outOffset] = ConvertToShort(decodedData[i]);
}
samplesDecoded += frameSize;
}
return samplesDecoded;
}
private static short ConvertToShort(float value)
{
// PCM saturation
if (value > 32767.0f)
value = 32767.0f;
else if (value < -32768.0f)
value = -32768.0f;
// Convert to short and save to buffer
return (short)Math.Round(value);
}
}
}