The correction of the mp4 muxer on files encoded with vp9, I think the same could also happen to webp

[tiuvi]

Este es el mensaje de error

You can see the demo at
https://tiuvi.com/videoEditorWebCodecs
If the demo is inoperative try it later, it is hosted on my own PC

The file was an mp4 file processed by webcodecs with vp9 codec and opus audio and packaged with this library in a webm container
That webm file is the one that I am now trying to transform back into webm to see that the same file can be processed several times but it gives an error.

[Vanilagy]

Lo siento, no entiendo del todo. ¿Estás insinuando que hay un error con los archivos WebM que produce mi muxer? ¿O el error está en otra parte?

[tiuvi]

Well, I produced a webm file with your muxer and then I tried to do demuxer again and it gave this error.
It is possible that it is in your library or in the demuxer library, I could not confirm the truth.
https://github.com/jscodec/jswebm

Yes it is true that I had to change this line because it threw an error and it did not work
Next week I will investigate more to see where the problem could be if you want.

In the muxer mp4 library it also produced unsigned -4 files when using vp9, maybe the error could also be here.

[tiuvi]

I provide more data if you do an ebml analysis with https://github.com/node-ebml/node-ebml you can see which track is undefined, I don't know that could be a problem.