本地合成录制

const recorder = srtc.createLocalCompositeRecorder();

await recorder.start({
  width: 1280,
  height: 720,
  fps: 15,
  videoItems: [
    {
      id: 'local-camera',
      track: localCameraTrack,
      label: '我',
      rect: { x: 0, y: 0, width: 640, height: 360 },
      fit: 'contain',
    },
    {
      id: 'remote-user-1-camera',
      track: remoteVideoTrack,
      label: '远端用户',
      rect: { x: 640, y: 0, width: 640, height: 360 },
      fit: 'contain',
    },
  ],
  audioTracks: [
    localMicTrack,
    remoteAudioMixTrack,
  ],
});

// 会议翻页、宫格变化或订阅关系变化后，更新当前录制视角。
recorder.updateVideoItems(nextVideoItems);
await recorder.updateAudioTracks(nextAudioTracks);

// 暂停与恢复作用于同一个最终文件。
recorder.pause();
recorder.resume();

// 结束录制，返回完整的 webm Blob。
const blob = await recorder.stop();

const url = URL.createObjectURL(blob);
const a = document.createElement('a');
a.href = url;
a.download = 'recording.webm';
a.click();
URL.revokeObjectURL(url);

const remoteAudioMixTrack = await srtc.subscribeRemoteAudioMixTrack();

await recorder.updateAudioTracks([
  localMicTrack,
  remoteAudioMixTrack,
]);

await recorder.start({
  videoItems,
  audioTracks,
  timeslice: 5000, // 每 5 秒产出一个分片
  onDataAvailable: (chunk) => {
    uploadChunk(chunk); // 业务层上传逻辑
  },
});

// 'inactive' 未开始或已结束 | 'recording' 录制中 | 'paused' 暂停
const state = recorder.getState();

// 不再使用时释放内部资源（canvas、AudioContext、MediaRecorder 等）
recorder.destroy();