Media/WebRTC/WebRTC Debugging
Reporting WebRTC Call Issues
The best way to report an issue is through Bugzilla using this link. Describing the issue you've run into, and include a URL along, with the details of the call setup.
For simple issues, the first place to look is to check the web developer console for error messages related to media format issues. If you see messages here related to WebRTC, getUserMedia, or getDisplayMedia, please add this information to your bug.
Share Your about:webrtc Contents
- While your call is still ongoing, open a tab and visit about:webrtc
- Click "Clear History" to clear the stats from other recent calls which are no longer ongoing.
- At the bottom of the page click 'Save Page', and save this file.
- Add this file as an attachment to your bug.
This file contains statistics about your call, the signalling that was used to setup your call, and information about the network transports.
Logging
Logging can be enabled through the "Enable WebRTC Log Preset" button at the bottom of [about:webrtc]. Alternatively one can set the following environment variable:
MOZ_LOG="jsep:5,sdp:5,signaling:5,mtransport:5,RTCRtpReceiver:5,RTCRtpSender:5,RTCDMTFSender:5,VideoFrameConverter:5,WebrtcTCPSocket:5,CamerasChild:5,CamerasParent:5,VideoEngine:5,ShmemPool:5,TabShare:5,MediaChild:5,MediaParent:5,MediaManager:5,MediaTrackGraph:5,cubeb:5,MediaStream:5,MediaStreamTrack:5,DriftCompensator:5,ForwardInputTrack:5,MediaRecorder:5,MediaEncoder:5,TrackEncoder:5,VP8TrackEncoder:5,Muxer:5,GetUserMedia:5,MediaPipeline:5,PeerConnectionImpl:5,WebAudioAPI:5,webrtc_trace:5,RTCRtpTransceiver:5,ForwardedInputTrack:5,HTMLMediaElement:5,HTMLMediaElementEvents:5"
Note that webrtc_trace will not be active until "Enable WebRTC Log Preset" is pressed.
| Module | Component | Function | Notes |
|---|---|---|---|
| jsep | signalling | JSEP state machine | |
| sdp | signalling | SDP parsing | |
| mtransport | networking | network transports | |
| RTCRtpReceiver | networking | receiving media and media control packets | |
| RTCRtpSender | networking | sending media and media control packets | |
| RTCDMTFSender | networking | sending DTMF messages | |
| VideoFrameConverter | ? | ? | |
| WebrtcTCPSocket | networking | ? | |
| CamerasChild | media capture | Content process end of IPC channel for receiving frames from media capture devices | |
| CamerasParent | media capture | Parent process end of IPC channel for sending frames from media capture devices | |
| VideoEngine | media capture | Orchestrates capture of frames from media capture devices in the parent process | |
| ShmemPool | media capture | Object pool of shared memory frame buffers for transferring media capture frames from parent to child process | |
| TabShare | media capture | ? | |
| MediaChild | media | ? | |
| MediaParent | media | ? | |
| MediaManager | media | ? | |
| MediaTrackGraph | media | ? | |
| cubeb | media | ? | |
| MediaStream | media | ? | |
| MediaStreamTrack | media | ? | |
| DriftCompensator | media | ? | |
| ForwardInputTrack | media | ? | |
| MediaRecorder | media | ? | |
| MediaEncoder | media | ? | |
| TrackEncoder | media | ? | |
| VP8TrackEncoder | media | ? | |
| Muxer | media | ? | |
| MediaPipeline | network | ??? delivers media packets from the transport | |
| PeerConnectionImpl | JS API | implements the RTCPeerConnection object | |
| WebAudioAPI | ?? | ? | |
| webrtc_trace | webrtc | libwebrtc logging | needs to be enabled from [about:webrtc] |
| RTCRtpTransceiver | JS API | implements the RTCRtpTransceiver object | |
| ForwardedInputTrack | ?? | ? | |
| HTMLMediaElement | ?? | ? | |
| HTMLMediaElementEvents | ?? | ? |
Profiling
One can use the "WebRTC" preset on the [about:logging] page with the Firefox Performance Profiler.
Examining Call Performance Issues
Enabling Call Stats History
Call stats history is enabled by default in Nightly. To enable in release builds open [about:config], and change "media.aboutwebrtc.hist.enabled" to true. This will keep a history windows of stats for a number of recent calls, allowing for inspection in [about:webrtc] after a call has completed.
Dumping Call Stats
One can dump a JSON blob of call stats for an active call, or a recent call if call stats history is enabled. There are two buttons in [about:webrtc] to do this, "Copy Report" and "Copy Report History". The former will create a copy of the most recent stats for the PeerConnection. The later will copy all the history of stats reports that [about:webrtc] has accumulated for that PeerConnection, this can be up to several minutes of stats.