/// <summary>
/// Decodes an encoded frame.
/// </summary>
/// <param name="encodedFrame">The encoded frame.</param>
/// <returns></returns>
public override AudioBuffer Decode(byte[] encodedFrame)
{
if (_Decoder == null)
{
_Decoder = new Decoder(ClockRate, Channels, PacketTime);
Link.GetRemoteStream().DisablePLC = true;
}
if (_LastRTPSequenceNumber == -1)
{
_LastRTPSequenceNumber = _CurrentRTPSequenceNumber;
return DecodeNormal(encodedFrame);
}
else
{
var sequenceNumberDelta = RTPPacket.GetSequenceNumberDelta(_CurrentRTPSequenceNumber, _LastRTPSequenceNumber);
if (sequenceNumberDelta <= 0)
{
return null;
}
_LastRTPSequenceNumber = _CurrentRTPSequenceNumber;
var missingPacketCount = sequenceNumberDelta - 1;
var previousFrames = new AudioBuffer[missingPacketCount];
var plcFrameCount = (missingPacketCount > 1) ? missingPacketCount - 1 : 0;
if (plcFrameCount > 0)
{
Log.InfoFormat("Adding {0} frames of loss concealment to incoming audio stream. Packet sequence violated.", plcFrameCount.ToString());
for (var i = 0; i < plcFrameCount; i++)
{
previousFrames[i] = DecodePLC();
}
}
var fecFrameCount = (missingPacketCount > 0) ? 1 : 0;
if (fecFrameCount > 0)
{
var fecFrame = DecodeFEC(encodedFrame);
var fecFrameIndex = missingPacketCount - 1;
if (fecFrame == null)
{
previousFrames[fecFrameIndex] = DecodePLC();
}
else
{
previousFrames[fecFrameIndex] = fecFrame;
}
}
var frame = DecodeNormal(encodedFrame);
frame.PreviousBuffers = previousFrames;
return frame;
}
}
/// <summary>
/// Destroys the codec.
/// </summary>
public override void Destroy()
{
if (_Encoder != null)
{
_Encoder.Destroy();
_Encoder = null;
}
if (_Decoder != null)
{
_Decoder.Destroy();
_Decoder = null;
}
}