Real isConfigSupported() calls against this browser at 1280x720, 30fps, 5 Mbps. Results vary by OS and hardware, nothing is hard-coded.

• H.264 Baseline avc1.42001fNot checked
• H.264 High avc1.640028Not checked
• VP8 vp8Not checked
• VP9 vp09.00.10.08Not checked
• AV1 av01.0.05M.08Not checked
• HEVC hvc1.1.6.L93.B0Not checked

Audio

• Opus opusNot checked
• AAC-LC mp4a.40.2Not checked
• FLAC flacNot checked

Encoder config validator

Build a config and validate it for real before writing encode code.

// Minimal real WebCodecs encode loop
const encoder = new VideoEncoder({
  output: (chunk, meta) => {
    // chunk is an EncodedVideoChunk; mux it (e.g. into MP4/WebM) yourself
    console.log(chunk.type, chunk.byteLength, meta);
  },
  error: (e) => console.error(e),
});

encoder.configure({
  codec: "avc1.42001f",
  width: 1280,
  height: 720,
  bitrate: 5_000_000,
  framerate: 30,
});

const frame = new VideoFrame(canvas, { timestamp: 0 }); // from a <canvas>
encoder.encode(frame, { keyFrame: true });
frame.close();
await encoder.flush();
encoder.close();

WebCodecs gives you raw encoded chunks, not a file. Pair it with a muxer (mp4-muxer, webm-muxer) to write playable video.