1652343 - Decodig H264 WebRTC Stream

Status: RESOLVED INCOMPLETE

(Core :: WebRTC, defect)

Description

[bepandre]

User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:77.0) Gecko/20100101 Firefox/77.0

Steps to reproduce:

Tried streaming a video over webrtc. The video is encoded in h264 with the baseline profile (source from raspberrypi camera).

My OS is MacOS Catalina and I'm running firefox 78.
I did a test where I downgraded firefox to 77 and there it worked again.

The same thing worked in firefox 77 though. Stopped working on firefox 78.

Actual results:

The WebRTC Connection is established according to the connection state.
I can also verify that information in about:webrt. Packets are arriving (receinved bytes increase).

But the stream is never played.

Expected results:

There should be video appearing in the <video> tag in the HTML. Like it was in version 77

Comment 1

[BugBot [:suhaib / :marco/ :calixte]]

Bugbug thinks this bug should belong to this component, but please revert this change in case of error.

Comment 2

[Alex Chronopoulos [:achronop]]

Dan, can you please help me triage this one?

Comment 3

[Dan Minor [:dminor]]

Thank you for reporting this bug. H264 seems to be working fine on a call between Firefox <-> Safari, so it is not completely broken. I'm not aware of any changes between Firefox 77 and 78 that would have affected this. Could you please run a mozregression (https://mozilla.github.io/mozregression/) to see if you can narrow down what caused the problem? Thanks!

Comment 4

[bepandre]

Attachment: Screenshot 2020-07-21 at 21.24.33.png

This is a screenshot from mozregression, seems to have found a commit.

Comment 5

[bepandre]

Attachment: mozregression log

Thanks for taking interest in the bug. I ran mozregression but not entirely sure what to post here. It seems to have found a commit so I'll post the log and a screenshot as attachment.

Another thing I should maybe point out: Firefox does not seem to send h264 as an option in the SDP unless I toggle the media.webrtc.hw.h264.enabled flag in about:config.

Comment 6

[Alex Chronopoulos [:achronop]]

Dan, I am re-adding the NI just to satisfy the triage process.

Comment 7

[Dan Minor [:dminor]]

(In reply to bepandre from comment #5)

Thanks for taking interest in the bug. I ran mozregression but not entirely
sure what to post here. It seems to have found a commit so I'll post the log
and a screenshot as attachment.

Thanks for running the mozregression. The commit you found was associated with Bug 1631965. Since that looks like audio only changes, it's not clear why this would be breaking things for you.

Another thing I should maybe point out: Firefox does not seem to send h264
as an option in the SDP unless I toggle the media.webrtc.hw.h264.enabled
flag in about:config.

You need to allow enough time for the OpenH264 plugin to download before you can test things with the software codec. You can check in about:plugins to see if it is present. It would be very helpful to know if this is failing with OpenH264, the hardware codec or both. I'm sorry I forgot to mention waiting for OpenH264 to download in my last comment. It usually takes 10 or 20 seconds after the browser starts, but it can make doing a mozregression error prone. I hope this didn't end up wasting your time.

Comment 8

[Dan Minor [:dminor]]

Unfortunately, there is nothing more we can do here without more information.