public static ImmutableList <MediaTrack> FromSdp(SessionDescription sdp, Uri baseUri, MimeType filter = null)
{
var builder = ImmutableList.CreateBuilder <MediaTrack>();
string sdpConnectionAddr = baseUri.Host;
if (sdp.Connection != null && IsAddressSet(sdp.Connection.Address))
{
sdpConnectionAddr = sdp.Connection.Address;
}
sdp.MediaDescriptions.ForEach(md =>
{
Uri controlUri = baseUri;
string type = md.Media.ToString().ToLower();
string subType = "unknown";
// Prefer the media description's connection address over the sdp connection address.
var connectionAddr = md.Connection != null && !string.IsNullOrEmpty(md.Connection.Address)
? md.Connection.Address
: sdpConnectionAddr;
var rtmpmaps = md.GetRtpMaps();
// Via spec there can be multiple types and rtpmaps, but
// we will assume a single one since all cameras/encoders
// appear to only provide one per Media Description.
var rtpmap = rtmpmaps.IsEmpty ? FromPayloadType(md.MediaFormats[0]) : rtmpmaps.First();
subType = rtpmap.EncodingName;
var control = md.Attributes.Where(a => "control" == a.Name).DefaultIfEmpty(null).First();
if (control != null)
{
controlUri = ResolveUri(baseUri, new Uri(control.Value, UriKind.RelativeOrAbsolute));
}
var mimeType = MimeType.Create(type, rtpmap.EncodingName);
if (mimeType.Is(APPLICATION_SPOOFED))
{
// The MediaGateway and Vxpro us spoofing to determine the client's intentions of
// either playing live or recorded data. Because of the current design they do not
// have a way to know the client's intentions until a play call is issued that contains
// and RTSP Range header with an absolute start-time.
//
// To handle metadata, in a pretty hacky way, a new media description is added to the SDP
// of type application/vnd.pelco.spoofed to indicate to a client that the data is bogus
// The client should continue processing up until the play call is made. At this point the
// MediaGateway or VxPro will issues a redirect to the actual source.
//
// We will make a bogus metadata track to allow the client to continue processing.
builder.Add(MediaTrack.CreateBuilder()
.Address(Dns.GetHostAddresses(baseUri.Host)[0])
.Port(md.Port)
.Type(mimeType)
.Uri(controlUri)
.Build());
}
else if ((filter != null && mimeType.Is(filter)) || (filter == null))
{
// If a filter is defined only return tracks that match the
// defined filter type; otherwise, return all tracks.
if (IsAddressSet(connectionAddr))
{
// If defined as 0.0.0.0 or ::0 then replace with the SDP connection address.
connectionAddr = sdpConnectionAddr;
}
var addrs = Dns.GetHostAddresses(connectionAddr);
builder.Add(MediaTrack.CreateBuilder()
.Address(Dns.GetHostAddresses(connectionAddr)[0])
.Port(md.Port)
.RtpMap(rtpmap)
.Type(mimeType)
.Uri(controlUri)
.Build());
}
});
return(builder.ToImmutable());
}
