/// <summary>
/// Validates RtpCodecCapability. It may modify given data by adding missing
/// fields with default values.
/// It throws if invalid.
/// </summary>
public static void ValidateRtpCodecCapability(RtpCodecCapability codec)
{
// mimeType is mandatory.
if (codec.MimeType.IsNullOrWhiteSpace())
{
throw new ArgumentException(nameof(codec.MimeType));
}
var mimeType = codec.MimeType.ToLower();
if (!MimeTypeRegex.IsMatch(mimeType))
{
throw new ArgumentException(nameof(codec.MimeType));
}
// Just override kind with media component in mimeType.
codec.Kind = mimeType.StartsWith("video") ? MediaKind.Video : MediaKind.Audio;
// preferredPayloadType is optional.
// 在 Node.js 实现中，判断了 preferredPayloadType 在有值的情况下的数据类型。在强类型语言中不需要。
// clockRate is mandatory.
// 在 Node.js 实现中，判断了 mandatory 的数据类型。在强类型语言中不需要。
// channels is optional. If unset, set it to 1 (just if audio).
if (codec.Kind == MediaKind.Audio && (!codec.Channels.HasValue || codec.Channels < 1))
{
codec.Channels = 1;
}
// parameters is optional. If unset, set it to an empty object.
if (codec.Parameters == null)
{
codec.Parameters = new Dictionary <string, object>();
}
foreach (var item in codec.Parameters)
{
var key = item.Key;
var value = item.Value;
if (value == null)
{
codec.Parameters[item.Key] = "";
value = "";
}
if (!value.IsStringType() && !value.IsNumericType())
{
throw new ArgumentOutOfRangeException($"invalid codec parameter[key:{key}, value:{value}]");
}
// Specific parameters validation.
if (key == "apt" && !value.IsNumericType())
{
throw new ArgumentOutOfRangeException("invalid codec apt parameter");
}
}
// rtcpFeedback is optional. If unset, set it to an empty array.
if (codec.RtcpFeedback == null)
{
codec.RtcpFeedback = Array.Empty <RtcpFeedback>();
}
foreach (var fb in codec.RtcpFeedback)
{
ValidateRtcpFeedback(fb);
}
}
/// <summary>
/// Generate RTP capabilities for the Router based on the given media codecs and
/// mediasoup supported RTP capabilities.
/// </summary>
public static RtpCapabilities GenerateRouterRtpCapabilities(RtpCodecCapability[] mediaCodecs)
{
if (mediaCodecs == null)
{
throw new ArgumentNullException(nameof(mediaCodecs));
}
// Normalize supported RTP capabilities.
ValidateRtpCapabilities(RtpCapabilities.SupportedRtpCapabilities);
var clonedSupportedRtpCapabilities = RtpCapabilities.SupportedRtpCapabilities.DeepClone <RtpCapabilities>();
var dynamicPayloadTypes = DynamicPayloadTypes.DeepClone <int[]>().ToList();
var caps = new RtpCapabilities
{
Codecs = new List <RtpCodecCapability>(),
HeaderExtensions = clonedSupportedRtpCapabilities.HeaderExtensions
};
foreach (var mediaCodec in mediaCodecs)
{
// This may throw.
ValidateRtpCodecCapability(mediaCodec);
var matchedSupportedCodec = clonedSupportedRtpCapabilities
.Codecs !
.Where(supportedCodec => MatchCodecs(mediaCodec, supportedCodec, false)).FirstOrDefault();
if (matchedSupportedCodec == null)
{
throw new Exception($"media codec not supported[mimeType:{mediaCodec.MimeType}]");
}
// Clone the supported codec.
var codec = matchedSupportedCodec.DeepClone <RtpCodecCapability>();
// If the given media codec has preferredPayloadType, keep it.
if (mediaCodec.PreferredPayloadType.HasValue)
{
codec.PreferredPayloadType = mediaCodec.PreferredPayloadType;
// Also remove the pt from the list in available dynamic values.
dynamicPayloadTypes.Remove(codec.PreferredPayloadType.Value);
}
// Otherwise if the supported codec has preferredPayloadType, use it.
else if (codec.PreferredPayloadType.HasValue)
{
// No need to remove it from the list since it's not a dynamic value.
}
// Otherwise choose a dynamic one.
else
{
// Take the first available pt and remove it from the list.
var pt = dynamicPayloadTypes.FirstOrDefault();
if (pt == 0)
{
throw new Exception("cannot allocate more dynamic codec payload types");
}
dynamicPayloadTypes.RemoveAt(0);
codec.PreferredPayloadType = pt;
}
// Ensure there is not duplicated preferredPayloadType values.
if (caps.Codecs.Any(c => c.PreferredPayloadType == codec.PreferredPayloadType))
{
throw new Exception("duplicated codec.preferredPayloadType");
}
// Merge the media codec parameters.
codec.Parameters = codec.Parameters.Merge(mediaCodec.Parameters);
// Append to the codec list.
caps.Codecs.Add(codec);
// Add a RTX video codec if video.
if (codec.Kind == MediaKind.Video)
{
// Take the first available pt and remove it from the list.
var pt = dynamicPayloadTypes.FirstOrDefault();
if (pt == 0)
{
throw new Exception("cannot allocate more dynamic codec payload types");
}
dynamicPayloadTypes.RemoveAt(0);
var rtxCodec = new RtpCodecCapability
{
Kind = codec.Kind,
MimeType = $"{codec.Kind.GetEnumMemberValue()}/rtx",
PreferredPayloadType = pt,
ClockRate = codec.ClockRate,
Parameters = new Dictionary <string, object>
{
{ "apt", codec.PreferredPayloadType }
},
RtcpFeedback = Array.Empty <RtcpFeedback>(),
};
// Append to the codec list.
caps.Codecs.Add(rtxCodec);
}
}
return(caps);
}