/// <summary>
/// Validates RtpHeaderExtensionParameteters. It may modify given data by adding missing
/// fields with default values.
/// It throws if invalid.
/// </summary>
public static void ValidateRtpHeaderExtensionParameters(RtpHeaderExtensionParameters ext)
{
if (ext == null)
{
throw new ArgumentNullException(nameof(ext));
}
// uri is mandatory.
if (ext.Uri.IsNullOrEmpty())
{
throw new ArgumentException(nameof(ext.Uri));
}
// id is mandatory.
// 在 Node.js 实现在，判断了 id 的数据类型。在强类型语言中不需要。
// encrypt is optional. If unset set it to false.
if (!ext.Encrypt.HasValue)
{
ext.Encrypt = false;
}
// parameters is optional. If unset, set it to an empty object.
// TODO: (alby)强类型无法转 Empty 对象。
if (ext.Parameters == null)
{
ext.Parameters = new Dictionary <string, object>();
}
foreach (var item in ext.Parameters)
{
var key = item.Key;
var value = item.Value;
if (value == null)
{
ext.Parameters[item.Key] = "";
value = "";
}
if (!value.IsStringType() && !value.IsNumericType())
{
throw new ArgumentOutOfRangeException($"invalid codec parameter[key:${ key }, value:${ value }]");
}
}
}
/// <summary>
/// Generate RTP parameters to be internally used by Consumers given the RTP
/// parameters in a Producer and the RTP capabilities in the Router.
/// </summary>
public static RtpParameters GetConsumableRtpParameters(MediaKind kind, RtpParameters parameters, RtpCapabilities caps, RtpMapping rtpMapping)
{
var consumableParams = new RtpParameters
{
Codecs = new List <RtpCodecParameters>(),
HeaderExtensions = new List <RtpHeaderExtensionParameters>(),
Encodings = new List <RtpEncodingParameters>(),
Rtcp = new RtcpParameters(),
};
foreach (var codec in parameters.Codecs)
{
if (IsRtxMimeType(codec.MimeType))
{
continue;
}
var consumableCodecPt = rtpMapping.Codecs
.Where(entry => entry.PayloadType == codec.PayloadType)
.Select(m => m.MappedPayloadType)
.FirstOrDefault();
var matchedCapCodec = caps.Codecs
.Where(capCodec => capCodec.PreferredPayloadType == consumableCodecPt)
.FirstOrDefault();
var consumableCodec = new RtpCodecParameters
{
MimeType = matchedCapCodec.MimeType,
PayloadType = matchedCapCodec.PreferredPayloadType.Value, // TODO: (alby)注意 null 引用
ClockRate = matchedCapCodec.ClockRate,
Channels = matchedCapCodec.Channels,
Parameters = codec.Parameters, // Keep the Producer codec parameters.
RtcpFeedback = matchedCapCodec.RtcpFeedback
};
consumableParams.Codecs.Add(consumableCodec);
var consumableCapRtxCodec = caps.Codecs
.Where(capRtxCodec => IsRtxMimeType(capRtxCodec.MimeType) && MatchCodecsWithPayloadTypeAndApt(consumableCodec.PayloadType, capRtxCodec.Parameters))
.FirstOrDefault();
if (consumableCapRtxCodec != null)
{
var consumableRtxCodec = new RtpCodecParameters
{
MimeType = consumableCapRtxCodec.MimeType,
PayloadType = consumableCapRtxCodec.PreferredPayloadType.Value, // TODO: (alby)注意 null 引用
ClockRate = consumableCapRtxCodec.ClockRate,
Channels = consumableCapRtxCodec.Channels,
Parameters = consumableCapRtxCodec.Parameters, // Keep the Producer codec parameters.
RtcpFeedback = consumableCapRtxCodec.RtcpFeedback
};
consumableParams.Codecs.Add(consumableRtxCodec);
}
}
foreach (var capExt in caps.HeaderExtensions) // TODO: (alby)注意 null 引用
{
// Just take RTP header extension that can be used in Consumers.
if (capExt.Kind != kind || (capExt.Direction != RtpHeaderExtensionDirection.SendReceive && capExt.Direction != RtpHeaderExtensionDirection.SendOnly))
{
continue;
}
var consumableExt = new RtpHeaderExtensionParameters
{
Uri = capExt.Uri,
Id = capExt.PreferredId,
Encrypt = capExt.PreferredEncrypt,
Parameters = new Dictionary <string, object>(),
};
consumableParams.HeaderExtensions.Add(consumableExt);
}
// Clone Producer encodings since we'll mangle them.
var consumableEncodings = parameters.Encodings.DeepClone <List <RtpEncodingParameters> >();
for (var i = 0; i < consumableEncodings.Count; ++i)
{
var consumableEncoding = consumableEncodings[i];
var mappedSsrc = rtpMapping.Encodings[i].MappedSsrc;
// Remove useless fields.
// 在 Node.js 实现中，rid, rtx, codecPayloadType 被 delete 了。
consumableEncoding.Rid = null;
consumableEncoding.Rtx = null;
consumableEncoding.CodecPayloadType = null;
// Set the mapped ssrc.
consumableEncoding.Ssrc = mappedSsrc;
consumableParams.Encodings.Add(consumableEncoding);
}
consumableParams.Rtcp = new RtcpParameters
{
CNAME = parameters.Rtcp.CNAME, // TODO: (alby)注意 null 引用
ReducedSize = true,
Mux = true,
};
return(consumableParams);
}