React Video Recorder (using mp4-muxer library) bug fixing

Important : Apply if you have two cameras connected to your pc.

The app is running here : https://videoo-capture-hk5ku2vhva-uc.a.run.app/

Here is what we have right now :
- A video and screen recorder using React
- Output n number of videos in MP4 format
- The recorder has 4K or HD capabilities for high-quality recordings wherever the input device supports.

We have three bugs :

1. Choppy audio.
2. When a Second video input device, presentation shows primary video input device, but twice.
3. Screen recordings, multiple stream recording stress testing ends up with Matroska container, it is not mp4 stream, it should be mp4 container.

Follow these steps to reproduce "Choppy audio, missing audio slices issue":

1. Start a webcam recording
2. Wait for one minute.
3. Download the recorded content.
4. You can hear the audio have choppy output, where there are gaps in every audio frame.

I am looking for a skilled React developer who can help me fix a bug in the React Video Recorder using the mp4-muxer library.

Skills and experience required:
- Strong proficiency in React
- Experience working with the mp4-muxer library
- Solid understanding of audio recording and encoding

If you have the necessary skills and experience, please submit your proposal.