1113283 - Firefox nightly webrtc openh264 call fails in 'level-asymmetry-allowed=1' is not answered

Status: RESOLVED INVALID

(Core :: WebRTC, defect)

Description

[Frank Coco]

Attachment: File illustrating SDP offered by Firefox and answered by Bria.

User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:31.0) Gecko/20100101 Firefox/31.0
Build ID: 20141125031119

Steps to reproduce:

Using the 12/16/14 Firefox nightly build, I made a webrtc call to a Bria softphone. Note that the Bria is configured to only accept h264 as the video codec.



Actual results:

The call fails and firefox issues the following error:

"Set remote description failed!" DOMError { name: "InvalidSessionDescriptionError", message: "Failed to negotiate codec details for all codecs" }

It appears that if Firefox doesn't receive an SDP answer with ''level-asymmetry-allowed=1', the call fails.



Expected results:

The call should have succeeded.

It appears the Firefox is in violation of of RFC 6184 - RTP Payload Format for H.264 Video. 

If the 'level-asymmetry-allowed' isn't answered, it should accept the answer and default to level-asymmetry as not allowed.

Excerpt from Section 8.1
==================
level-asymmetry-allowed:
This parameter MAY be used in SDP Offer/Answer to indicate
whether level asymmetry, i.e., sending media encoded at a
different level in the offerer-to-answerer direction than the
level in the answerer-to-offerer direction, is allowed. The
value MAY be equal to either 0 or 1. When the parameter is not
present, the value MUST be inferred to be equal to 0. The
value 1 in both the offer and the answer indicates that level
asymmetry is allowed. The value of 0 in either the offer or
the answer indicates that level asymmetry is not allowed.

If level-asymmetry-allowed is equal to 0 (or not present) in
either the offer or the answer, level asymmetry is not allowed.
In this case, the level to use in the direction from the
offerer to the answerer MUST be the same as the level to use in
the opposite direction.

Comment 1

[Maire Reavy [:mreavy]]

An answer with profile-level-id of 428014 does not match an offer of 42e01f, per the spec -- though many devices ignore this detail.