WebRTC encoded transform - Modify Metadata functions

concepts

1. Modify Metadata probe

   Build a real encoded transform; mutate rtpTimestamp, contributingSources, and mimeType on a frame; observe the constructed RTCEncodedVideoFrame.

2. Timestamp-shifted forwarding

   The chromestatus motivation by name: "altering the timestamp of a frame to introduce a delay." Visualises an SFU-style pipeline that shifts every video frame's RTP timestamp by a configurable offset for lip-sync or translation use cases.

3. Network resilience lab

   Three additional scenarios where setMetadata is the right tool (simulcast layer switch, RTP timestamp resync, mid-call rotation). Dial loss and jitter; see a 20-frame stream rendered with vs without the metadata-modifying transform, and read the JS that produced the rescue.

4. Frame metadata editor

   Interactive before/after view of a simulated 12-frame video stream. Select any frame and override its RTP timestamp, payload type, spatial/temporal index, and contributing sources — the panel updates to highlight exactly which fields setMetadata() changed.

why it shipped

This feature is needed to support use cases that involve manipulation of encoded video / audio frames beyond inline processing of its payload.

references

• ChromeStatus entry
• Spec