Android WebRTC - createAnswer() is missing recvonly video

[Sean Horton]

I'm trying to receive video on Android with native WebRTC. WebRTC was built from 5481.

Below is the sdp offer from a janus server and then android's answer.

Android's answer is missing "BUNDLE video" and other codec options.

The below offer is type "[...]SAVPF 96 97", which android does not make an appropriate answer for. However, if the janus offer is instead "[...]SAVPF 98 99" android seems to correctly create an answer.

OFFER FROM JANUS:
    v=0
    o=- omitted 1 IN IP4 omitted
    s=Mountpoint omitted
    t=0 0
    a=group:BUNDLE video
    a=msid-semantic: WMS janus
    m=video 9 UDP/TLS/RTP/SAVPF 96 97
    c=IN IP4 omitted
    a=sendonly
    a=mid:video
    a=rtcp-mux
    a=ice-ufrag:omitted
    a=ice-pwd:omitted
    a=ice-options:trickle
    a=fingerprint:omitted
    a=setup:actpass
    a=rtpmap:96 H264/90000
    a=fmtp:96 pachetization-mode-1
    a=rtcp-fb:96 nack
    a=rtcp-fb:96 nack pli
    a=rtcp-fb:96 goog-remb
    a=extmap:1 urn:ietf:params:rtp-hdrext:sdes:mid
    a=rtpmap:97 rtx/90000
    a=fmtp:97 apt=96
    a=ssrc-group:FID omitted omitted
    a=msid:janus janusv0
    a=ssrc:omitted cname:janus
    a=ssrc:omitted msid:janus janusv0
    a=ssrc:omitted mslabel:janus
    a=ssrc:omitted label:janusv0
    a=ssrc:omitted cname:janus
    a=ssrc:omitted msid:janus janusv0
    a=ssrc:omitted mslabel:janus
    a=ssrc:omitted label:janusv0
    a=candidate:1 1 udp omitted omitted omitted typ host
    a=end-of-candidates


ANSWER FROM ANDROID:
    v=0
    o=- omitted 2 IN IP4 127.0.0.1
    s=-
    t=0 0
    a=group:BUNDLE
    a=msid-semantic: WMS
    m=video 0 UDP/TLS/RTP/SAVPF 0
    c=IN IP4 0.0.0.0
    a=rtcp:9 IN IP4 0.0.0.0
    a=ice-ufrag:omitted
    a=ice-pwd:omitted
    a=ice-options:trickle renomination
    a=fingerprint: omitted
    a=setup:active
    a=mid:video
    a=extmap:1 urn:ietf:params:rtp-hdrext:sdes:mid
    a=recvonly
    a=rtcp-mux


I can manually edit the android answer to include the below, and video correctly plays:
    ...
    a=group:BUNDLE video
    m=video 9 UDP/TLS/RTP/SAVPF 96 97
    ...
    a=rtpmap:96 H264/90000
    a=rtcp-fb:96 goog-remb
    a=rtcp-fb:96 nack
    a=rtcp-fb:96 nack pli
    a=fmtp:96 level-asymmetry-allowed=1;packetization-mode=1;profile-level-id=42e01f
    a=rtpmap:97 rtx/90000
    a=fmtp:97 apt=96


I'm not sure if their is a reason the answer is not automatically generating an sdp with "BUNDLE video". It doesn't seem appropriate for me to manually add the extra video options. 

[Philipp Hancke]

Your offer from Janus seems to lack a profile-level-id which makes libwebrtc think there are no common codecs.

You are applying the edits between createAnswer and setLocalDescription and that works?!

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[Sean Horton]

Thanks! That helped me find the issue. 

The offer from janus has a typo. The offer says "pachetization-mode-1", but should be "packetization-mode=1"

Regardless, to answer your question. Yes, I was doing,

- setRemoteDescription

- createAnswer

- edit the answer

- setLocalDescription

and it was working. But, after fixing the typo it's working as expected.

Thanks again.