// Adds multi-ssrc based simulcast into the given SDP media section offer.
public static void AddLegacySimulcast(MediaObject offerMediaObject, int numStreams)
{
if (numStreams <= 1)
{
throw new Exception("'numStreams must be greater than 1");
}
// Get the SSRC.
var ssrcMsidLine = (offerMediaObject.MediaDescription.Attributes.Ssrcs ?? new List <Ssrc>())
.FirstOrDefault(line => line.Attribute == "msid");
if (ssrcMsidLine is null)
{
throw new Exception("'a=ssrc line with msid information not found");
}
var values = ssrcMsidLine.Value.Split(' ');
var streamId = values[0];
var trackId = values.Length > 1 ? values[1] : null;
var firstSsrc = ssrcMsidLine.Id;
uint?firstRtxSsrc = null;
// Get the SSRC for RTX.
(offerMediaObject.MediaDescription.Attributes.SsrcGroups ?? new List <SsrcGroup>()).Any(line =>
{
if (line.Semantics != "FID")
{
return(false);
}
if (uint.Parse(line.SsrcIds[0]) == firstSsrc)
{
firstRtxSsrc = uint.Parse(line.SsrcIds[1]);
return(true);
}
else
{
return(false);
}
});
var ssrcCnameLine = offerMediaObject.MediaDescription.Attributes.Ssrcs
.FirstOrDefault(line => line.Attribute == "cname");
if (ssrcCnameLine is null)
{
throw new Exception("a=ssrc line with cname information not found");
}
var cname = ssrcCnameLine.Value;
List <uint> ssrcs = new();
List <uint> rtxSsrcs = new();
for (uint i = 0; i < numStreams; ++i)
{
ssrcs.Add(firstSsrc + i);
if (firstRtxSsrc is not null)
{
rtxSsrcs.Add((uint)(firstRtxSsrc + i));
}
}
offerMediaObject.MediaDescription.Attributes.SsrcGroups = new List <SsrcGroup>();
offerMediaObject.MediaDescription.Attributes.Ssrcs = new List <Ssrc>();
var x = ssrcs.Select(ssrc => ssrc.ToString()).ToArray();
offerMediaObject.MediaDescription.Attributes.SsrcGroups.Add(new SsrcGroup
{
Semantics = "SIM",
SsrcIds = ssrcs.Select(ssrc => ssrc.ToString()).ToArray()
});
for (int i = 0; i < ssrcs.Count; ++i)
{
var ssrc = ssrcs[i];
offerMediaObject.MediaDescription.Attributes.Ssrcs.Add(new Ssrc
{
Id = ssrc,
Attribute = "cname",
Value = cname
});
offerMediaObject.MediaDescription.Attributes.Ssrcs.Add(new Ssrc
{
Id = ssrc,
Attribute = "msid",
Value = $"{ streamId} { trackId}"
});
}
for (int i = 0; i < rtxSsrcs.Count; ++i)
{
var ssrc = ssrcs[i];
var rtxSsrc = rtxSsrcs[i];
offerMediaObject.MediaDescription.Attributes.Ssrcs.Add(new Ssrc
{
Id = rtxSsrc,
Attribute = "cname",
Value = cname
});
offerMediaObject.MediaDescription.Attributes.Ssrcs.Add(new Ssrc
{
Id = rtxSsrc,
Attribute = "msid",
Value = $"{streamId} ${ trackId}"
});
offerMediaObject.MediaDescription.Attributes.SsrcGroups.Add(new SsrcGroup
{
Semantics = "FID",
SsrcIds = new string[] { $"{ ssrc} ${ rtxSsrc}" }
});
}
}
public AnswerMediaSection(
IceParameters iceParameters,
IceCandidate[] iceCandidates,
DtlsParameters dtlsParameters,
SctpParameters sctpParameters,
PlainRtpParameters plainRtpParameters,
bool planB,
MediaObject offerMediaObject,
RtpParameters offerRtpParameters,
RtpParameters answerRtpParameters,
ProducerCodecOptions codecOptions,
bool extmapAllowMixed) : base(iceParameters, iceCandidates, dtlsParameters, planB)
{
_mediaObject.MediaDescription.Attributes.Mid = offerMediaObject.MediaDescription.Attributes.Mid;
_mediaObject.MediaDescription.Media = offerMediaObject.MediaDescription.Media;
_mediaObject.MediaDescription.Proto = offerMediaObject.MediaDescription.Proto;
if (plainRtpParameters is null)
{
_mediaObject.MediaDescription.ConnectionData = new ConnectionData
{
NetType = NetType.Internet,
AddrType = AddrType.Ip4,
ConnectionAddress = "127.0.0.1"
};
_mediaObject.MediaDescription.Port = 7;
}
else
{
_mediaObject.MediaDescription.ConnectionData = new ConnectionData
{
NetType = NetType.Internet,
AddrType = plainRtpParameters.IpVersion,
ConnectionAddress = plainRtpParameters.Ip
};
_mediaObject.MediaDescription.Port = plainRtpParameters.Port;
}
switch (offerMediaObject.MediaDescription.Media)
{
case MediaType.Audio:
case MediaType.Video:
{
_mediaObject.MediaDescription.Attributes.RecvOnly = true;
_mediaObject.MediaDescription.Attributes.Rtpmaps = new List <Rtpmap>();
_mediaObject.MediaDescription.Attributes.RtcpFbs = new List <RtcpFb>();
_mediaObject.MediaDescription.Attributes.Fmtps = new List <Fmtp>();
foreach (var codec in answerRtpParameters.Codecs)
{
var xxx = codec;
Rtpmap rtpmap = new()
{
PayloadType = codec.PayloadType,
EncodingName = GetCodecName(codec),
ClockRate = codec.ClockRate,
Channels = codec.Channels > 1 ? codec.Channels : null
};
_mediaObject.MediaDescription.Attributes.Rtpmaps.Add(rtpmap);
var codecParameters = Utils.Clone(codec.Parameters, new Dictionary <string, object>()
{
});
if (codecOptions is not null)
{
var offerCodec = offerRtpParameters.Codecs
.First(c => c.PayloadType == codec.PayloadType);
switch (codec.MimeType.ToLower())
{
case "audio/opus":
{
if (codecOptions.OpusStereo.HasValue)
{
offerCodec.Parameters["sprop-stereo"] =
codecOptions.OpusStereo == true ? 1 : 0;
codecParameters["stereo"] =
codecOptions.OpusStereo == true ? 1 : 0;
}
if (codecOptions.OpusFec.HasValue)
{
offerCodec.Parameters["useinbandfec"] =
codecOptions.OpusFec == true ? 1 : 0;
codecParameters["useinbandfec"] =
codecOptions.OpusFec == true ? 1 : 0;
}
if (codecOptions.OpusDtx.HasValue)
{
offerCodec.Parameters["usedtx"] =
codecOptions.OpusDtx == true ? 1 : 0;
codecParameters["usedtx"] =
codecOptions.OpusDtx == true ? 1 : 0;
}
if (codecOptions.OpusMaxPlaybackRate.HasValue)
{
codecParameters["maxplaybackrate"] =
codecOptions.OpusMaxPlaybackRate;
}
if (codecOptions.OpusMaxAverageBitrate.HasValue)
{
codecParameters["maxaveragebitrate"] =
codecOptions.OpusMaxAverageBitrate;
}
if (codecOptions.OpusPtime.HasValue)
{
codecParameters["ptime"] =
codecOptions.OpusPtime;
}
}
break;
case "video/vp8":
case "video/vp9":
case "video/h264":
case "video/h265":
{
if (codecOptions.VideoGoogleStartBitrate.HasValue)
{
codecParameters["x-google-start-bitrate"] =
codecOptions.VideoGoogleStartBitrate;
}
if (codecOptions.VideoGoogleMaxBitrate.HasValue)
{
codecParameters["x-google-max-bitrate"] =
codecOptions.VideoGoogleMaxBitrate;
}
if (codecOptions.VideoGoogleMinBitrate.HasValue)
{
codecParameters["x-google-min-bitrate"] =
codecOptions.VideoGoogleMinBitrate;
}
}
break;
}
}
Fmtp fmtp = codecParameters.ToFmtp(codec.PayloadType);
if (!string.IsNullOrEmpty(fmtp.Value))
{
_mediaObject.MediaDescription.Attributes.Fmtps.Add(fmtp);
}
foreach (var fb in codec.RtcpFeedback)
{
RtcpFb rtcpFb = new()
{
PayloadType = codec.PayloadType,
Type = fb.Type,
SubType = fb.Parameter
};
_mediaObject.MediaDescription.Attributes.RtcpFbs.Add(rtcpFb);
}
}
_mediaObject.MediaDescription.Fmts ??= new List <string>();
((List <string>)_mediaObject.MediaDescription.Fmts).AddRange(answerRtpParameters.Codecs
.Select(codec => codec.PayloadType.ToString()));
_mediaObject.MediaDescription.Attributes.Extmaps = new List <Extmap>();
foreach (var headerExtension in answerRtpParameters.HeaderExtensions)
{
// Don't add a header extension if not present in the offer.
var found = offerMediaObject.MediaDescription.Attributes.Extmaps
.Any(localExt => localExt.Uri.ToString() == headerExtension.Uri);
if (!found)
{
continue;
}
Extmap ext = new()
{
Uri = new Uri(headerExtension.Uri),
Value = headerExtension.Id
};
_mediaObject.MediaDescription.Attributes.Extmaps.Add(ext);
}
// Allow both 1 byte and 2 bytes length header extensions.
if (extmapAllowMixed && offerMediaObject.MediaDescription.Attributes.ExtmapAllowMixed.HasValue &&
offerMediaObject.MediaDescription.Attributes.ExtmapAllowMixed == true)
{
_mediaObject.MediaDescription.Attributes.ExtmapAllowMixed = true;
}
// Simulcast.
//// DEBUG HACK
if (offerMediaObject.MediaDescription.Media == MediaType.Video)
{
Console.WriteLine("PUT A BP HERE...");
}
if (offerMediaObject.MediaDescription.Attributes.Simulcast is not null)
{
_mediaObject.MediaDescription.Attributes.Simulcast = new()
{
Direction = RidDirection.Recv,
IdList = offerMediaObject.MediaDescription.Attributes.Simulcast.IdList
};
_mediaObject.MediaDescription.Attributes.Rids = new List <Rid>();
foreach (var rid in offerMediaObject.MediaDescription.Attributes.Rids)
{
if (rid.Direction != RidDirection.Send)
{
continue;
}
_mediaObject.MediaDescription.Attributes.Rids.Add(new Rid
{
Id = rid.Id,
Direction = RidDirection.Recv
});
}
}
// Simulcast (draft version 03).
else if (offerMediaObject.Simulcast03 is not null)
{
_mediaObject.Simulcast03 = new()
{
Value = offerMediaObject.Simulcast03.Value.Replace(RidDirection.Send.DisplayName(),
RidDirection.Recv.DisplayName())
};
_mediaObject.MediaDescription.Attributes.Rids = new List <Rid>();
foreach (var rid in offerMediaObject.MediaDescription.Attributes.Rids)
{
if (rid.Direction != RidDirection.Send)
{
continue;
}
_mediaObject.MediaDescription.Attributes.Rids.Add(new Rid
{
Id = rid.Id,
Direction = RidDirection.Recv
});
}
}
_mediaObject.MediaDescription.Attributes.RtcpMux = true;
_mediaObject.MediaDescription.Attributes.RtcpRsize = true;
if (_planB && _mediaObject.MediaDescription.Media == MediaType.Video)
{
_mediaObject.XGoogleFlag = "conference";
}
break;
}
case MediaType.Application:
{
// New spec.
if (offerMediaObject.MediaDescription.Attributes.SctpPort.Port.GetType() == typeof(int))
{
_mediaObject.MediaDescription.Fmts = new List <string> {
"webrtc-datachannel"
};
_mediaObject.MediaDescription.Attributes.SctpPort = new SctpPort
{
Port = sctpParameters.Port
};
_mediaObject.MediaDescription.Attributes.MaxMessageSize = new MaxMessageSize
{
Size = sctpParameters.MaxMessageSize
};
}
// Old spec.
else if (offerMediaObject.SctpMap is not null)
{
_mediaObject.MediaDescription.Fmts = new List <string> {
sctpParameters.Port.ToString()
};
_mediaObject.SctpMap = new()
{
App = "webrtc-datachannel",
SctpMapNumber = sctpParameters.Port,
MaxMessageSize = sctpParameters.MaxMessageSize
};
}
break;
}
}
}
public static RtpEncodingParameters[] GetRtpEncodings(MediaObject offerMediaObject)
{
List <uint> ssrcs = (offerMediaObject.MediaDescription.Attributes.Ssrcs ?? new List <Ssrc>())
.Select(s => s.Id)
.Distinct()
.ToList();
if (ssrcs.Count == 0)
{
throw new Exception("XXXXno a=ssrc lines found");
}
Dictionary <uint, uint?> ssrcToRtxSsrc = new();
// First assume RTX is used.
foreach (var line in offerMediaObject.MediaDescription.Attributes.SsrcGroups ?? new List <SsrcGroup>())
{
if (line.Semantics != "FID")
{
continue;
}
var ssrc = uint.Parse(line.SsrcIds[0]);
var rtxSsrc = uint.Parse(line.SsrcIds[1]);
if (ssrcs.Contains(ssrc))
{
// Remove both the SSRC and RTX SSRC from the set so later we know that they
// are already handled.
ssrcs.Remove(ssrc);
ssrcs.Remove(rtxSsrc);
// Add to the map.
ssrcToRtxSsrc.Add(ssrc, rtxSsrc);
}
}
// If the set of SSRCs is not empty it means that RTX is not being used, so take
// media SSRCs from there.
foreach (var ssrc in ssrcs)
{
// Add to the map.
ssrcToRtxSsrc.Add(ssrc, null);
}
List <RtpEncodingParameters> encodings = new();
foreach (var item in ssrcToRtxSsrc)
{
RtpEncodingParameters encoding = new();
encoding.Ssrc = item.Key;
if (item.Value is not null)
{
encoding.Rtx = new() { Ssrc = item.Value }
}
;
encodings.Add(encoding);
}
return(encodings.ToArray());
}
