public byte[] EncodeAudio(byte[] pcm, AudioCodecsEnum codec, AudioSamplingRatesEnum sampleRate)
{
// Convert buffer into a PCM sample (array of signed shorts) that's
// suitable for input into the chosen encoder.
short[] pcmSigned = new short[pcm.Length / 2];
for (int i = 0; i < pcmSigned.Length; i++)
{
pcmSigned[i] = BitConverter.ToInt16(pcm, i * 2);
}
return(EncodeAudio(pcmSigned, codec, sampleRate));
}
/// <summary>
/// Sends a stream containing 16 bit PCM audio to the remote party. Calling this method
/// will pause the existing audio source until the stream has been sent.
/// </summary>
/// <param name="audioStream">The stream containing the 16 bit PCM, sampled at either 8 or 16 Khz,
/// to send to the remote party.</param>
/// <param name="streamSampleRate">The sample rate of the supplied PCM samples. Supported rates are
/// 8 or 16 KHz.</param>
private void InitialiseSendAudioFromStreamTimer(Stream audioStream, AudioSamplingRatesEnum streamSampleRate)
{
if (audioStream != null && audioStream.Length > 0)
{
Log.LogDebug($"Sending audio stream length {audioStream.Length}.");
_streamSendInProgress = true;
_streamSourceSampleRate = streamSampleRate;
_streamSourceReader = new BinaryReader(audioStream);
_streamSourceTimer = new Timer(SendStreamSample, null, Timeout.Infinite, Timeout.Infinite);
}
}
/// <summary>
/// Same as the async method of the same name but returns a task that waits for the
/// stream send to complete.
/// </summary>
/// <param name="audioStream">The stream containing the 16 bit PCM sampled at either 8 or 16 Khz
/// to send to the remote party.</param>
/// <param name="streamSampleRate">The sample rate of the supplied PCM samples. Supported rates are
/// 8 or 16 KHz.</param>
/// <returns>A task that completes once the stream has been fully sent.</returns>
public Task SendAudioFromStream(Stream audioStream, AudioSamplingRatesEnum streamSampleRate)
{
if (audioStream == null && audioStream.Length == 0)
{
return(Task.CompletedTask);
}
else
{
TaskCompletionSource <bool> tcs = new TaskCompletionSource <bool>(TaskCreationOptions.RunContinuationsAsynchronously);
Action handler = null;
handler = () =>
{
tcs.SetResult(true);
OnSendFromAudioStreamComplete -= handler;
};
OnSendFromAudioStreamComplete += handler;
SendAudioFromStreamAsync(audioStream, streamSampleRate);
return(tcs.Task);
}
}
/// <summary>
/// Sends a stream containing 16 bit PCM audio to the remote party. Calling this method
/// will pause the existing audio source until the stream has been sent.
/// </summary>
/// <param name="audioStream">The stream containing the 16 bit PCM sampled at either 8 or 16 Khz
/// to send to the remote party.</param>
/// <param name="streamSampleRate">The sample rate of the supplied PCM samples. Supported rates are
/// 8 or 16 KHz.</param>
public void SendAudioFromStreamAsync(Stream audioStream, AudioSamplingRatesEnum streamSampleRate)
{
if (audioStream != null && audioStream.Length > 0)
{
if (_audioPcmStreamTimer == null)
{
// Create a dummy timer object so it can be locked to prevent another
// thread interrupting.
TimerCallback noop = (state) => { };
_audioPcmStreamTimer = new Timer(noop);
}
lock (_audioPcmStreamTimer)
{
Log.LogDebug($"Sending audio stream length {audioStream.Length}.");
_streamSendInProgress = true;
_audioPcmSampleRate = streamSampleRate;
_audioPcmStreamReader = new StreamReader(audioStream);
_audioPcmStreamTimer = new Timer(SendPcmSample, null, 0, AUDIO_SAMPLE_PERIOD_MILLISECONDS);
}
}
}
/// <summary>
/// Same as the async method of the same name but returns a task that waits for the
/// stream send to complete.
/// </summary>
/// <param name="audioStream">The stream containing the 16 bit PCM sampled at either 8 or 16Khz
/// to send to the remote party.</param>
/// <param name="streamSampleRate">The sample rate of the supplied PCM samples. Supported rates are
/// 8 or 16 KHz.</param>
/// <returns>A task that completes once the stream has been fully sent.</returns>
public async Task SendAudioFromStream(Stream audioStream, AudioSamplingRatesEnum streamSampleRate)
{
if (audioStream != null && audioStream.Length > 0)
{
// Stop any existing send from stream operation.
StopSendFromAudioStream();
TaskCompletionSource <bool> tcs = new TaskCompletionSource <bool>(TaskCreationOptions.RunContinuationsAsynchronously);
Action handler = null;
handler = () =>
{
tcs.TrySetResult(true);
OnSendFromAudioStreamComplete -= handler;
};
OnSendFromAudioStreamComplete += handler;
InitialiseSendAudioFromStreamTimer(audioStream, streamSampleRate);
_streamSourceTimer.Change(AUDIO_SAMPLE_PERIOD_MILLISECONDS, AUDIO_SAMPLE_PERIOD_MILLISECONDS);
await tcs.Task;
}
}
public void ExternalAudioSourceRawSample(AudioSamplingRatesEnum samplingRate, uint durationMilliseconds,
short[] sample)
{
throw new NotImplementedException(); //not needed
}
/// <summary>
/// Encodes a 16 bit PCM sample and sends to the remote party.
/// </summary>
/// <param name="sample">The PCM 16 bit *=8KHz sample to send.</param>
/// <param name="sampleLength">The length of the sample</param>
/// <param name="sampleRate">The sample rate of either 8 or 16 KHz for the supplied sample.</param>
private void EncodeAndSendAudioSample(byte[] sample, int sampleLength, AudioSamplingRatesEnum sampleRate)
{
byte[] encodedSample = null;
// Convert buffer into a PCM sample (array of signed shorts) that's
// suitable for input into the chosen encoder.
short[] pcm = new short[sampleLength / 2];
for (int i = 0; i < pcm.Length; i++)
{
pcm[i] = BitConverter.ToInt16(sample, i * 2);
}
if (_sendingFormat.FormatCodec == SDPMediaFormatsEnum.G722)
{
if (sampleRate == AudioSamplingRatesEnum.SampleRate16KHz)
{
// No up sampling required.
int outputBufferSize = pcm.Length / 2;
encodedSample = new byte[outputBufferSize];
int res = _g722Codec.Encode(_g722CodecState, encodedSample, pcm, pcm.Length);
}
else
{
// Up sample the supplied PCM signal by doubling each sample.
int outputBufferSize = pcm.Length;
encodedSample = new byte[outputBufferSize];
short[] pcmUpsampled = new short[pcm.Length * 2];
for (int i = 0; i < pcm.Length; i++)
{
pcmUpsampled[i * 2] = pcm[i];
pcmUpsampled[i * 2 + 1] = pcm[i];
}
_g722Codec.Encode(_g722CodecState, encodedSample, pcmUpsampled, pcmUpsampled.Length);
}
}
else
{
Func <short, byte> encode = (_sendingFormat.FormatCodec == SDPMediaFormatsEnum.PCMA)
? (Func <short, byte>)ALawEncoder.LinearToALawSample
: MuLawEncoder.LinearToMuLawSample;
if (sampleRate == AudioSamplingRatesEnum.SampleRate8KHz)
{
// No down sampling required.
int outputBufferSize = pcm.Length;
encodedSample = new byte[outputBufferSize];
for (int index = 0; index < pcm.Length; index++)
{
encodedSample[index] = encode(pcm[index]);
}
}
else
{
// Down sample the supplied PCM signal by skipping every second sample.
int outputBufferSize = pcm.Length / 2;
encodedSample = new byte[outputBufferSize];
int encodedIndex = 0;
// Skip every second sample.
for (int index = 0; index < pcm.Length; index += 2)
{
encodedSample[encodedIndex++] = encode(pcm[index]);
}
}
}
int sampleRateTicks = (sampleRate == AudioSamplingRatesEnum.SampleRate8KHz) ? 8000 : 16000;
int durationMilliseconds = (sample.Length * 1000) / (sampleRateTicks * 2);
int rtpTimestampDuration = _sendingAudioRtpRate / 1000 * durationMilliseconds;
//Log.LogDebug($"send audio frame sample rate {sampleRateTicks}, duration ms {durationMilliseconds}, rtp timestamp duration {rtpTimestampDuration}.");
SendAudioFrame((uint)rtpTimestampDuration, (int)_sendingFormat.FormatCodec, encodedSample);
}
public void ExternalAudioSourceRawSample(AudioSamplingRatesEnum samplingRate, uint durationMilliseconds, short[] sample) => OnAudioSourceRawSample.Invoke(samplingRate, durationMilliseconds, sample);
public byte[] EncodeAudio(short[] pcm, AudioCodecsEnum codec, AudioSamplingRatesEnum sampleRate)
{
byte[] encodedSample = null;
if (codec == AudioCodecsEnum.G722)
{
if (_g722Codec == null)
{
_g722Codec = new G722Codec();
_g722CodecState = new G722CodecState(G722_BIT_RATE, G722Flags.None);
}
if (sampleRate == AudioSamplingRatesEnum.Rate16KHz)
{
// No up sampling required.
int outputBufferSize = pcm.Length / 2;
encodedSample = new byte[outputBufferSize];
int res = _g722Codec.Encode(_g722CodecState, encodedSample, pcm, pcm.Length);
}
else
{
// Up sample the supplied PCM signal by doubling each sample.
int outputBufferSize = pcm.Length;
encodedSample = new byte[outputBufferSize];
short[] pcmUpsampled = new short[pcm.Length * 2];
for (int i = 0; i < pcm.Length; i++)
{
pcmUpsampled[i * 2] = pcm[i];
pcmUpsampled[i * 2 + 1] = pcm[i];
}
_g722Codec.Encode(_g722CodecState, encodedSample, pcmUpsampled, pcmUpsampled.Length);
}
return(encodedSample);
}
else if (codec == AudioCodecsEnum.PCMA ||
codec == AudioCodecsEnum.PCMU)
{
Func <short, byte> encode = (codec == AudioCodecsEnum.PCMA) ?
(Func <short, byte>)ALawEncoder.LinearToALawSample : MuLawEncoder.LinearToMuLawSample;
if (sampleRate == AudioSamplingRatesEnum.Rate8KHz)
{
// No down sampling required.
int outputBufferSize = pcm.Length;
encodedSample = new byte[outputBufferSize];
for (int index = 0; index < pcm.Length; index++)
{
encodedSample[index] = encode(pcm[index]);
}
}
else
{
// Down sample the supplied PCM signal by skipping every second sample.
int outputBufferSize = pcm.Length / 2;
encodedSample = new byte[outputBufferSize];
int encodedIndex = 0;
// Skip every second sample.
for (int index = 0; index < pcm.Length; index += 2)
{
encodedSample[encodedIndex++] = encode(pcm[index]);
}
}
return(encodedSample);
}
else
{
throw new ApplicationException($"Audio format {codec} cannot be encoded.");
}
}
/// <summary>
/// Event handler for receiving RTP packets from the remote party.
/// </summary>
/// <param name="remoteEP">The remote end point the RTP was received from.</param>
/// <param name="codec">The encoding codec of the packets.</param>
/// <param name="rtpPacket">The RTP packet with the media sample.</param>
public byte[] DecodeAudio(byte[] encodedSample, AudioCodecsEnum codec, AudioSamplingRatesEnum sampleRate)
{
bool wants8kSamples = sampleRate == AudioSamplingRatesEnum.Rate8KHz;
bool wants16kSamples = sampleRate == AudioSamplingRatesEnum.Rate16KHz;
if (codec == AudioCodecsEnum.G722)
{
if (_g722Decoder == null)
{
_g722Decoder = new G722Codec();
_g722DecoderState = new G722CodecState(G722_BIT_RATE, G722Flags.None);
}
short[] decodedPcm16k = new short[encodedSample.Length * 2];
int decodedSampleCount = _g722Decoder.Decode(_g722DecoderState, decodedPcm16k, encodedSample, encodedSample.Length);
// The decoder provides short samples but streams and devices generally seem to want
// byte samples so convert them.
byte[] pcm8kBuffer = (wants8kSamples) ? new byte[decodedSampleCount] : null;
byte[] pcm16kBuffer = (wants16kSamples) ? new byte[decodedSampleCount * 2] : null;
for (int i = 0; i < decodedSampleCount; i++)
{
var bufferSample = BitConverter.GetBytes(decodedPcm16k[i]);
// For 8K samples the crude re-sampling to get from 16K to 8K is to skip
// every second sample.
if (pcm8kBuffer != null && i % 2 == 0)
{
pcm8kBuffer[(i / 2) * 2] = bufferSample[0];
pcm8kBuffer[(i / 2) * 2 + 1] = bufferSample[1];
}
// G722 provides 16k samples.
if (pcm16kBuffer != null)
{
pcm16kBuffer[i * 2] = bufferSample[0];
pcm16kBuffer[i * 2 + 1] = bufferSample[1];
}
}
return(pcm8kBuffer ?? pcm16kBuffer);
}
else if (codec == AudioCodecsEnum.PCMA ||
codec == AudioCodecsEnum.PCMU)
{
Func <byte, short> decode = (codec == AudioCodecsEnum.PCMA) ?
(Func <byte, short>)ALawDecoder.ALawToLinearSample : MuLawDecoder.MuLawToLinearSample;
byte[] pcm8kBuffer = (wants8kSamples) ? new byte[encodedSample.Length * 2] : null;
byte[] pcm16kBuffer = (wants16kSamples) ? new byte[encodedSample.Length * 4] : null;
for (int i = 0; i < encodedSample.Length; i++)
{
var bufferSample = BitConverter.GetBytes(decode(encodedSample[i]));
// G711 samples at 8KHz.
if (pcm8kBuffer != null)
{
pcm8kBuffer[i * 2] = bufferSample[0];
pcm8kBuffer[i * 2 + 1] = bufferSample[1];
}
// The crude up-sampling approach to get 16K samples from G711 is to
// duplicate each 8K sample.
// TODO: This re-sampling approach introduces artifacts. Applying a low pass
// filter seems to be recommended.
if (pcm16kBuffer != null)
{
pcm16kBuffer[i * 4] = bufferSample[0];
pcm16kBuffer[i * 4 + 1] = bufferSample[1];
pcm16kBuffer[i * 4 + 2] = bufferSample[0];
pcm16kBuffer[i * 4 + 3] = bufferSample[1];
}
}
return(pcm8kBuffer ?? pcm16kBuffer);
}
else
{
throw new ApplicationException($"Audio format {codec} cannot be decoded.");
}
}
private void _FFmpegAudioSource_OnAudioSourceRawSample(AudioSamplingRatesEnum samplingRate, uint durationMilliseconds, short[] sample)
{
OnAudioSourceRawSample?.Invoke(samplingRate, durationMilliseconds, sample);
}
