SIPSorcery.VP8

A pure C# VP8 video codec for the SIPSorcery real-time communications library. No native binaries, no PInvoke -- runs anywhere .NET runs.

This is a port of Google's reference VP8 implementation (libvpx) into managed C#. Use this package when you want VP8 video support without the FFmpeg native dependency required by SIPSorceryMedia.FFmpeg.

Status

Path	State
Decoder	Working. Functional but slow -- the C-to-C# port hasn't been performance-tuned. Acceptable for low-resolution / low-frame-rate WebRTC peers.
Encoder -- keyframe (I-frame)	Working. DC_PRED for Y / UV, single token partition, default quantizer Q=32.
Encoder -- inter (P-frame)	Working. ZEROMV referencing LAST_FRAME for every macroblock. No real motion estimation yet (NEWMV is on the roadmap).
WebRTC interop	Verified end-to-end against Chrome via the example apps below.

For the technical write-up, the foundation-PR sequence, and the ongoing roadmap (real motion estimation, additional intra modes, GOLDEN / ALTREF references, loop filter), see diary/2026-04-26-Claude-Opus-4.7/result.md.

Installation

dotnet add package SIPSorcery
dotnet add package SIPSorcery.VP8

Quickstart -- send a VP8 test pattern over WebRTC

using SIPSorcery.Media;
using SIPSorcery.Net;
using Vpx.Net;

var pc = new RTCPeerConnection(null);

// VP8Codec implements both IVideoEncoder (encode) and IVideoSink (decode).
var vp8Codec = new VP8Codec();

// Wrap it as an encoder end-point.
var encoderEndPoint = new Vp8NetVideoEncoderEndPoint(vp8Codec);

// Drive it from a test pattern source -- pass the codec directly, no
// I420->BGR->I420 round-trip in the wiring.
var testPatternSource = new VideoTestPatternSource(vp8Codec);

var track = new MediaStreamTrack(testPatternSource.GetVideoSourceFormats(),
                                 MediaStreamStatusEnum.SendOnly);
pc.addTrack(track);

testPatternSource.OnVideoSourceEncodedSample += pc.SendVideo;
pc.OnVideoFormatsNegotiated += formats =>
    testPatternSource.SetVideoSourceFormat(formats.First());

await testPatternSource.StartVideo();

Configuration

VP8Codec exposes a few tuning knobs:

Property	Default	Purpose
BaseQIndex	32	VP8 base quantizer index, range 0-127. Lower = better quality, higher bitrate.
KeyframeIntervalFrames	30	One keyframe per N frames (1 keyframe/sec at 30 fps default). Set to 1 to force every frame to be a keyframe.

Examples

The repository includes two end-to-end demos that use this package:

• WebRTCGetStarted -- the main repo getting-started demo. Pure C# WebRTC server streaming an animated test pattern + audio to a browser, using SIPSorcery.VP8 as the video encoder. (Originally WebRTCGetStartedVP8Net; promoted to be the canonical getting-started example now that the pure C# VP8 path is the default for in-tree WebRTC video.)
• WebRTCClientVP8Net -- pure C# WebRTC client receiving a VP8 stream from a browser and decoding it locally.

Performance characteristics

• Encoder: optimised for allocation hygiene -- effectively zero allocations per frame after warmup. Single-threaded; one core comfortably handles 30 fps at typical webcam resolutions on a modern CPU.
• Decoder: not yet performance-tuned. For 1080p / 30 fps you'll want the FFmpeg-based decoder.

Related packages

• SIPSorcery -- the main real-time communications library.
• SIPSorceryMedia.Abstractions -- the IVideoEncoder interface this package implements.
• SIPSorceryMedia.FFmpeg -- alternative VP8 implementation via native FFmpeg (faster, but pulls in native dependencies and an LGPL licence).

License

BSD 3-Clause License. See LICENSE at the repo root.