Capture & Replay WebRTC video streams for debugging – video_replay 2025 update
Debugging WebRTC media issues, especially video, often requires access to the unencrypted RTP payloads. We talked about this back in 2017 already and had a great blog post on using the libWebRTC “video_replay” tool. While that post has aged remarkably well, video_replay has improved significantly, in particular since it is now possible to create the pcap directly from Chrome. video_replay has become my go-to tool for debugging video-related problems such as corruption or freezes and is frequently used in bug reports.
As the 2017 blog post mentions, Chrome has a command line flag to disable the WebRTC/SRTP encryption that works in Chrome Beta and Canary. However, this changes the SDP, which makes it less useful for debugging issues arising in production.
Chrome has been supporting dumping the RTP packets before and after encryption into the log files since December 2020 Chrome (four years already, time flies!). This can be enabled by starting Chrome with the following flags:
