WebCodecs Support

[seydx]

This PR adds a new WebCodecs-based streaming mode to go2rtc, delivering raw encoded frames over WebSocket for browser-side decoding via the WebCodecs API.

Features

• Raw encoded video/audio frames via WebSocket
• H.264 and H.265 video support
• AAC, Opus, PCMA, PCMU audio support (no server-side encoding needed)
• Binary frame protocol with 9-byte header
• AVCC to Annex-B conversion for browser compatibility
• Native-style player controls (play/pause, volume, fullscreen)
• GPU-accelerated rendering: WebGPU → WebGL2 → Canvas 2D (automatic fallback)
• Configurable renderer cascade via renderer query parameter

Usage

# Default (full cascade)
stream.html?src=camera&mode=webcodecs

# Force specific renderer
stream.html?src=camera&mode=webcodecs&renderer=webgl

# Skip WebGPU
stream.html?src=camera&mode=webcodecs&renderer=webgl,2d

[skrashevich]

Firefox

sure?

[AlexxIT]

https://caniuse.com/?search=VideoDecoder

[seydx]

WebCodecs is supported in all major browser, but hevc not:

Microsoft Edge on Windows

By default, Chromium browsers uses FFMpeg internally for WebCodecs API. However, Microsoft Edge, when running on Windows, uses Media Foundation decoders instead.

Decoding H.265 requires the HEVC Video Extensions ($0.99) or HEVC Video Extensions from Device Manufacturer (free but not available anymore) app from Microsoft Store.

Firefox

Firefox 133 supports playing H.265 videos, but does not support decoding H.265 streams using WebCodecs API yet.

[AlexxIT]

1. I like using new, modern technologies - it's cool.
2. I don't like the large amount of JavaScript code in the main player. Ideally, move everything into a separate file and make it easily connectable.
3. I'm not sure about the header for the binary format. It needs to be carefully designed. Otherwise, it will be difficult to change later. You're using uint32 for the time. That might not be enough. The header includes the packet size (maybe that's a good thing), but it isn't being used.

[seydx]

1. I like using new, modern technologies - it's cool.
2. I don't like the large amount of JavaScript code in the main player. Ideally, move everything into a separate file and make it easily connectable.
3. I'm not sure about the header for the binary format. It needs to be carefully designed. Otherwise, it will be difficult to change later. You're using uint32 for the time. That might not be enough. The header includes the packet size (maybe that's a good thing), but it isn't being used.

• Code is now split into three modules: video-webcodecs.js (player/decoder/audio/controls), video-renderer.js (WebGPU/WebGL2/Canvas2D cascade), and the existing video-rtc.js just wires them together
• Header redesigned: dropped the unused payload length field, timestamp is now uint64 (microseconds). 9 bytes total: flags(1) + timestamp_us(8) + payload.

[skrashevich]

merged into dev branch
@seydx please note the fixes in da908ca