invalid SDP: media 4 is invalid: config is missing

[fjfeijoo]

When trying to connect (for audio backchannel) to a Dahua camera through ONVIF I get an error parsing the SDP response:

The url of the RTSP is as follows:
rtsp://URL:PORT/cam/realmonitor?channel=1&subtype=0&unicast=true&proto=Onvif

CSeq: 3
Cache-Control: must-revalidate
Content-Base: rtsp://URL:PORT/cam/realmonitor?channel=1&subtype=0&unicast=true&proto=Onvif/
Content-Length: 1317
Content-Type: application/sdp
X-Accept-Dynamic-Rate: 1

v=0
o=- 2273421142 2273421142 IN IP4 0.0.0.0
s=Media Server
c=IN IP4 0.0.0.0
t=0 0
a=control:*
a=packetization-supported:DH
a=rtppayload-supported:DH
a=range:npt=now-
a=x-packetization-supported:IV
a=x-rtppayload-supported:IV
m=video 0 RTP/AVP 96
a=control:trackID=0
a=framerate:15.000000
a=rtpmap:96 H264/90000
a=fmtp:96 packetization-mode=1;profile-level-id=64002A;sprop-parameter-sets=Z2QAKqwsaoHgCJ+WbgoCCoAAAAMAgAAAD0IA,aO4xshsA
a=recvonly
m=audio 0 RTP/AVP 8
a=control:trackID=1
a=rtpmap:8 PCMA/8000
a=recvonly
m=application 0 RTP/AVP 107
a=control:trackID=4
a=rtpmap:107 vnd.onvif.metadata/90000
a=recvonly
m=audio 0 RTP/AVP 116 115 114 113 112 111 110 109 108 97 107 106 105 104 0 103 102 101 100 8
a=control:trackID=5
a=rtpmap:116 MPEG4-GENERIC/64000
a=rtpmap:115 MPEG4-GENERIC/48000
a=rtpmap:114 MPEG4-GENERIC/32000
a=rtpmap:113 MPEG4-GENERIC/16000
a=rtpmap:112 MPEG4-GENERIC/8000
a=rtpmap:111 G726-40/64000
a=rtpmap:110 G726-40/48000
a=rtpmap:109 G726-40/32000
a=rtpmap:108 G726-40/16000
a=rtpmap:97 G726-40/8000
a=rtpmap:107 PCMU/64000
a=rtpmap:106 PCMU/48000
a=rtpmap:105 PCMU/32000
a=rtpmap:104 PCMU/16000
a=rtpmap:0 PCMU/8000
a=rtpmap:103 PCMA/16000
a=rtpmap:102 PCMA/32000
a=rtpmap:101 PCMA/48000
a=rtpmap:100 PCMA/64000
a=rtpmap:8 PCMA/8000
 =sendonly

When connecting to the "normal" URL the SDP changes to something compatible:
rtsp://URL:PORT/cam/realmonitor?channel=1&subtype=0

v=0
o=- 2273415430 2273415430 IN IP4 0.0.0.0
s=Media Server
c=IN IP4 0.0.0.0
t=0 0
a=control:*
a=packetization-supported:DH
a=rtppayload-supported:DH
a=range:npt=now-
a=x-packetization-supported:IV
a=x-rtppayload-supported:IV
m=video 0 RTP/AVP 96
a=control:trackID=0
a=framerate:15.000000
a=rtpmap:96 H264/90000
a=fmtp:96 packetization-mode=1;profile-level-id=64002A;sprop-parameter-sets=Z2QAKqwsaoHgCJ+WbgoCCoAAAAMAgAAAD0IA,aO4xshsA
a=recvonly
m=audio 0 RTP/AVP 8
a=control:trackID=1
a=rtpmap:8 PCMA/8000
a=recvonly
m=audio 0 RTP/AVP 8
a=control:trackID=5
a=rtpmap:8 PCMA/8000
 =sendonly

Should gortsplib be compatible with the first SDP, or is this an issue on the camera itself?

Many thanks!

[aler9]

Hello, the issue here is that those audio codecs should also come with a config parameter that provides additional information:

a=rtpmap:116 MPEG4-GENERIC/64000
a=rtpmap:115 MPEG4-GENERIC/48000
a=rtpmap:114 MPEG4-GENERIC/32000
a=rtpmap:113 MPEG4-GENERIC/16000
a=rtpmap:112 MPEG4-GENERIC/8000

but they do not. I'll see what i can do about it.

[cedricve]

I have another error for avigilon cameras. Streams do setup properly, however when establishing the backchannel. I have the following.

invalid SDP: sdp: invalid syntax c=SM SM spk0_trackID3

Wireshark:

[cedricve]

On an Hikvision wireshark would look like this. I guess the current SDP formatter doesn't like the order or SM attribute.