private static SDP GetSDP(IPEndPoint rtpSocket, RTPPayloadTypesEnum audioPayloadType)
{
int samplingFrequency = RTPPayloadTypes.GetSamplingFrequency(audioPayloadType);
var sdp = new SDP()
{
SessionId = Crypto.GetRandomInt(5).ToString(),
Address = rtpSocket.Address.ToString(),
SessionName = "sipsorcery",
Timing = "0 0",
Connection = new SDPConnectionInformation(rtpSocket.Address.ToString()),
};
var audioAnnouncement = new SDPMediaAnnouncement()
{
Media = SDPMediaTypesEnum.audio,
MediaFormats = new List <SDPMediaFormat>()
{
new SDPMediaFormat((int)audioPayloadType, "PCMU", samplingFrequency)
}
};
audioAnnouncement.Port = rtpSocket.Port;
audioAnnouncement.ExtraAttributes.Add("a=sendrecv");
audioAnnouncement.ExtraAttributes.Add($"a=rtpmap:{DTMF_EVENT_PAYLOAD_ID} telephone-event/{samplingFrequency}");
audioAnnouncement.ExtraAttributes.Add($"a=fmtp:{DTMF_EVENT_PAYLOAD_ID} 0-15");
sdp.Media.Add(audioAnnouncement);
return(sdp);
}
/// <summary>
/// Creates a new RTP session. The synchronisation source and sequence number are initialised to
/// pseudo random values.
/// </summary>
/// <param name="payloadType">The payload type for the media attached to the sync source.</param>
/// <param name="srtpProtect">Optional secure DTLS context for encrypting RTP packets.</param>
/// <param name="srtcpProtect">Optional secure DTLS context for encrypting RTCP packets.</param>
public RTPSession(RTPPayloadTypesEnum payloadType, ProtectRtpPacket srtpProtect, ProtectRtpPacket srtcpProtect)
{
PayloadType = payloadType;
SrtpProtect = srtpProtect;
SrtcpProtect = srtcpProtect;
Ssrc = Convert.ToUInt32(Crypto.GetRandomInt(0, Int32.MaxValue));
SeqNum = Convert.ToUInt16(Crypto.GetRandomInt(0, UInt16.MaxValue));
}
/// <summary>
/// Attempts to get the sampling frequency of a payload type.
/// </summary>
/// <param name="payloadType">The payload type to get the frequency for.</param>
/// <returns>An integer representing the payload type's sampling frequency or 0 if it's
/// dynamic or can't be determined.</returns>
public static int GetSamplingFrequency(RTPPayloadTypesEnum payloadType)
{
switch (payloadType)
{
case RTPPayloadTypesEnum.PCMU:
case RTPPayloadTypesEnum.PCMA:
return(8000);
default:
return(0);
}
}
public void SetSendCodec(RTPPayloadTypesEnum codec)
{
m_sendRTPHeader.PayloadType = (int)codec;
}
