is audio supported?

[xeoshow]

Hi,

Just would like to know: when I am recording, I also have a background music which should be recorded, is this supported?
Thanks a lot.

[Damien Seguin]

Hi,

I don't intend to support Audio just yet, unless it can be added without increasing the complexity of the encoders. mp4-muxer demo and extending the WebCodecsEncoder would be a good place to start, but so far I have managed by merging audio and video on the file system after the export with ffmpeg.

[Merlin]

@dmnsgn Is there any way to get access to the muxer? I'm seeing mp4-muxer has methods to add audio data, but I'm not sure how to access those methods

[Damien Seguin]

@dmnsgn Is there any way to get access to the muxer? I'm seeing mp4-muxer has methods to add audio data, but I'm not sure how to access those methods

For the WebCodecsEncoder, you can pass muxerOptions and the muxer is added to the instance:

canvas-record/src/encoders/WebCodecsEncoder.js

Line 94 in 347bdff

 ...this.muxerOptions, 

So something like:

const audioSampleRate = 44100;
const encoder = new Encoders.WebCodecsEncoder({
  muxerOptions: {
    codec: 'aac',
    sampleRate: audioSampleRate,
    numberOfChannels: 1
  }
})

const { muxer } = encoder;

const audioEncoder = new AudioEncoder({
  output: (chunk, meta) => muxer.addAudioChunk(chunk, meta),
  error: e => console.error(e)
});
audioEncoder.configure({
  codec: 'mp4a.40.2',
  numberOfChannels: 1,
  sampleRate: audioSampleRate,
  bitrate: 128000
});

// ... use the audioEncoder to write data
// ... overwrite encoder.encode to add await audioEncoder.flush() after await this.encoder.flush();