videojs-record: ffmpeg.js plugin: record video+audio fails

Description

So far If I want record video+audio, it seem need use the RecordRTC? If use other plugin such as “webm-wasm” it seem will only record video without sound. So I want to try use some converter, such as ffmpeg.js with RecordRTC? But seem not luck with many config I try. Do you mind provide a example for convert to mp4 (Video+Audio) with common codec such as h264?

Steps to reproduce

Some config I test

			convertOptions: ['-f', 'mp4', '-codec:a', 'aac', '-codec:v', 'libx264'],
			pluginLibraryOptions: {
				outputType: 'video/mpeg'
			},

Results

Expected

Convert success

Actual

Throw exception

Error output

uncaught exception: [object Object] ffmpeg-worker-mp4.js:17:59

Additional Information

It may be not a bug, may need a tips for demo how to use ffmpeg with videojs record with Video+Audio?

versions

videojs

4.0.0

browsers

Firefox 76.0.1

OSes

MacOS