private void ParseFormatParametersAttribute(SdpMediaDescription mediaDescription, string value)
{
var separatorIdx = value.IndexOf(' ');
var payloadType = int.Parse(value.Substring(0, separatorIdx));
var formatParameters = value.Substring(separatorIdx + 1);
var mfd = mediaDescription.MediaFormatDescriptions[payloadType];
mfd.FormatParameters = formatParameters;
}
private void ParseRtpMapAttribute(SdpMediaDescription mediaDescription, string value)
{
var separatorIdx = value.IndexOf(' ');
var payloadType = int.Parse(value.Substring(0, separatorIdx));
var encoding = value.Substring(separatorIdx + 1);
var encodingParts = encoding.Split('/');
var mfd = mediaDescription.MediaFormatDescriptions[payloadType];
mfd.EncodingName = encodingParts[0];
if (int.TryParse(TryGet(encodingParts, 1), out var clockRate))
{
mfd.ClockRate = clockRate;
}
mfd.EncodingParameters = TryGet(encodingParts, 2);
}
/// <summary>
/// https://tools.ietf.org/html/rfc4566#section-5.14
///
/// m=<media> <port> <proto> <fmt> ...
///
/// A session description may contain a number of media descriptions.
/// Each media description starts with an "m=" field and is terminated by
/// either the next "m=" field or by the end of the session description.
/// A media field has several sub-fields:
/// </summary>
/// <param name="mediaId">
/// Used for identifying media streams within a
/// session description.
///
/// https://tools.ietf.org/html/rfc5888#section-4
/// </param>
/// <param name="media">
/// <media> is the media type. Currently defined media are "audio",
/// "video", "text", "application", and "message", although this list
/// may be extended in the future (see Section 8).
/// </param>
/// <param name="port">
/// <port> is the transport port to which the media stream is sent. The
/// meaning of the transport port depends on the network being used as
/// specified in the relevant "c=" field, and on the transport
/// protocol defined in the <proto> sub-field of the media field.
/// Other ports used by the media application (such as the RTP Control
/// Protocol (RTCP) port [19]) MAY be derived algorithmically from the
/// base media port or MAY be specified in a separate attribute (for
/// example, "a=rtcp:" as defined in [22]).
/// </param>
/// <param name="protocol">
/// <proto> is the transport protocol. The meaning of the transport
/// protocol is dependent on the address type field in the relevant
/// "c=" field. Thus a "c=" field of IP4 indicates that the transport
/// protocol runs over IP4.
/// </param>
public SdpMediaDescriptionBuilder AddMediaDescription(string mediaId, string media, int port, string protocol = "UDP/TLS/RTP/SAVPF")
{
var sdpMediaDescription = new SdpMediaDescription
{
MediaId = mediaId,
Media = media,
Port = port,
Protocol = protocol
};
_sessionDescription.MediaDescriptions.Add(sdpMediaDescription);
var mediaDescriptionBuilder = new SdpMediaDescriptionBuilder(sdpMediaDescription, this);
_mediaLineBuilders.Add(mediaDescriptionBuilder);
return(mediaDescriptionBuilder);
}
private void ParseSsrcAttribute(SdpMediaDescription mediaDescription, string value)
{
var parts = value.Split(' ');
var mediaAttributes = mediaDescription.MediaSourceAttributes;
mediaAttributes.Ssrc = uint.Parse(TryGet(parts, 0));
var ssrcParam = TryGet(parts, 1);
switch (ssrcParam)
{
case "cname":
mediaAttributes.CName = ssrcParam;
break;
case "msid":
mediaAttributes.MsId = ssrcParam;
mediaAttributes.MsIdAppData = TryGet(parts, 2);
break;
}
}
private void ParseMediaDescription(SdpSessionDescription sessionDescription, string medialine, TextReader stringReader)
{
var mediaDescription = new SdpMediaDescription();
var parts = medialine.Split(' ');
mediaDescription.Media = TryGet(parts, 0);
mediaDescription.Port = int.Parse(TryGet(parts, 1));
mediaDescription.Protocol = TryGet(parts, 2);
mediaDescription.MediaFormatDescriptions = parts.Skip(3)
.Select(int.Parse)
.ToDictionary(pt => pt, pt => new SdpMediaFormatDescription
{
PayloadType = pt
});
var line = stringReader.ReadLine();
while (line != null)
{
ParseSdpLine(line, out var key, out var value);
switch (key)
{
case "c":
mediaDescription.Connection = ParseConnectionLine(value);
break;
case "a":
ParseMediaDescriptionAttribute(mediaDescription, value);
break;
case "m":
ParseMediaDescription(sessionDescription, value, stringReader);
break;
}
line = stringReader.ReadLine();
}
sessionDescription.MediaDescriptions.Add(mediaDescription);
}
private static void ParseRtcpFeedbackCapabilityAttribute(SdpMediaDescription mediaDescription, string value)
{
var separatorIdx = value.IndexOf(' ');
var payloadTypeStr = value.Substring(0, separatorIdx);
var cap = value.Substring(separatorIdx + 1);
if (payloadTypeStr == "*")
{
foreach (var mfd in mediaDescription.MediaFormatDescriptions.Values)
{
mfd.RtcpFeedbackCapability.Add(cap);
}
}
else
{
var payloadType = int.Parse(payloadTypeStr);
var mfd = mediaDescription.MediaFormatDescriptions[payloadType];
mfd.RtcpFeedbackCapability.Add(cap);
}
}
public SdpMediaDescriptionBuilder(SdpMediaDescription sdpMediaDescription, SdpBuilder sdpBuilder)
{
_sdpMediaDescription = sdpMediaDescription;
_sdpBuilder = sdpBuilder;
}
private void ParseMediaDescriptionAttribute(SdpMediaDescription mediaDescription, string attribute)
{
ParseAttributeKeyValue(attribute, out var key, out var value);
switch (key)
{
case "control":
mediaDescription.RtspControlUrl = new Uri(value, UriKind.RelativeOrAbsolute);
break;
case "framerate":
mediaDescription.Framerate = decimal.Parse(value);
break;
case "sendrecv":
mediaDescription.SendReceiveMode = SendReceiveMode.SendRecv;
break;
case "sendonly":
mediaDescription.SendReceiveMode = SendReceiveMode.SendOnly;
break;
case "recvonly":
mediaDescription.SendReceiveMode = SendReceiveMode.RecvOnly;
break;
case "inactive":
mediaDescription.SendReceiveMode = SendReceiveMode.Inactive;
break;
case "mid":
mediaDescription.MediaId = value;
break;
case "ice-ufrag":
mediaDescription.IceAttributes.UsernameFragment = value;
break;
case "ice-pwd":
mediaDescription.IceAttributes.Password = value;
break;
case "ice-options":
mediaDescription.IceAttributes.Options = value;
break;
case "fingerprint":
var fingerprintParts = value.Split(' ');
mediaDescription.DtlsAttributes.HashFunc = TryGet(fingerprintParts, 0);
mediaDescription.DtlsAttributes.Fingerprint = TryGet(fingerprintParts, 1);
break;
case "setup":
mediaDescription.DtlsAttributes.Setup = value;
break;
case "rtpmap":
ParseRtpMapAttribute(mediaDescription, value);
break;
case "fmtp":
ParseFormatParametersAttribute(mediaDescription, value);
break;
case "rtcp-fb":
ParseRtcpFeedbackCapabilityAttribute(mediaDescription, value);
break;
case "ssrc":
ParseSsrcAttribute(mediaDescription, value);
break;
case "candidate":
var parts = value.Split(' ');
var sdpIceCandidate = new SdpIceCandidate();
sdpIceCandidate.Foundation = long.Parse(TryGet(parts, 0));
sdpIceCandidate.ComponentId = byte.Parse(TryGet(parts, 1));
sdpIceCandidate.Transport = TryGet(parts, 2);
sdpIceCandidate.Priority = uint.Parse(TryGet(parts, 3));
sdpIceCandidate.ConnectionAddress = TryGet(parts, 4);
sdpIceCandidate.Port = ushort.Parse(TryGet(parts, 5));
sdpIceCandidate.CandidateType = TryGet(parts, 7);
mediaDescription.IceCandidates.Add(sdpIceCandidate);
break;
case "end-of-candidates":
break;
}
}
