/// <summary>
/// Sends a pseudo-random sample to replicate white noise.
/// </summary>
private void SendNoiseSample(object state)
{
lock (_audioStreamTimer)
{
int bufferSize = SAMPLE_RATE / 1000 * AUDIO_SAMPLE_PERIOD_MILLISECONDS;
float[] linear = new float[bufferSize];
_signalGenerator.Read(linear, 0, bufferSize);
byte[] encodedSample = new byte[bufferSize];
short[] pcm = linear.Select(x => (short)(x * 32767f)).ToArray();
if (_sendingFormat.FormatCodec == SDPMediaFormatsEnum.G722)
{
_g722Codec.Encode(_g722CodecState, encodedSample, pcm, bufferSize);
}
else
{
for (int index = 0; index < bufferSize; index++)
{
if (_sendingFormat.FormatCodec == SDPMediaFormatsEnum.PCMA)
{
encodedSample[index] = ALawEncoder.LinearToALawSample(pcm[index]);
}
else
{
encodedSample[index] = MuLawEncoder.LinearToMuLawSample(pcm[index]);
}
}
}
SendAudioFrame((uint)bufferSize, (int)_sendingFormat.FormatCodec, encodedSample);
}
}
/// <summary>
/// Sends a sample from a signal generator generated waveform.
/// </summary>
private void SendSignalGeneratorSample(object state)
{
if (!_streamSendInProgress)
{
lock (_audioStreamTimer)
{
int sourceSampleRate = _sourceAudioSampleRate == AudioSamplingRatesEnum.Rate8KHz ? 8000 : 16000;
int inputBufferSize = sourceSampleRate / 1000 * AUDIO_SAMPLE_PERIOD_MILLISECONDS;
uint outputBufferSize = (uint)(_sendingAudioRtpRate / 1000 * AUDIO_SAMPLE_PERIOD_MILLISECONDS);
// Get the signal generator to generate the samples and then convert from
// signed linear to PCM.
float[] linear = new float[inputBufferSize];
_signalGenerator.Read(linear, 0, inputBufferSize);
short[] pcm = linear.Select(x => (short)(x * LINEAR_MAXIMUM)).ToArray();
byte[] encodedSample = _audioEncoder.EncodeAudio(pcm, _sendingFormat, _sourceAudioSampleRate);
OnAudioSourceEncodedSample?.Invoke(outputBufferSize, encodedSample);
}
}
}
/// <summary>
/// Sends a sample from a signal generator generated waveform.
/// </summary>
private void SendSignalGeneratorSample(object state)
{
if (!_streamSendInProgress)
{
lock (_audioStreamTimer)
{
int inputBufferSize = _sendingAudioSampleRate / 1000 * AUDIO_SAMPLE_PERIOD_MILLISECONDS;
int outputBufferSize = _sendingAudioRtpRate / 1000 * AUDIO_SAMPLE_PERIOD_MILLISECONDS;
// Get the signal generator to generate the samples and then convert from
// signed linear to PCM.
float[] linear = new float[inputBufferSize];
_signalGenerator.Read(linear, 0, inputBufferSize);
short[] pcm = linear.Select(x => (short)(x * 32767f)).ToArray();
// Both G711 (lossless) and G722 (lossy) encode to 64Kbps (unless the
// hard coded G722 rate of 64000 is changed).
byte[] encodedSample = new byte[outputBufferSize];
if (_sendingFormat.FormatCodec == SDPMediaFormatsEnum.G722)
{
_g722Codec.Encode(_g722CodecState, encodedSample, pcm, inputBufferSize);
}
else
{
Func <short, byte> encode = (_sendingFormat.FormatCodec == SDPMediaFormatsEnum.PCMA)
? (Func <short, byte>)ALawEncoder.LinearToALawSample
: MuLawEncoder.LinearToMuLawSample;
for (int index = 0; index < inputBufferSize; index++)
{
encodedSample[index] = encode(pcm[index]);
}
}
SendAudioFrame((uint)outputBufferSize, (int)_sendingFormat.FormatCodec, encodedSample);
}
}
}
