Allow configuring stderr/stdout

[LucCADORET]

Currently, the module prints data to stdout/stderr, which is undefined when using the library in a web worker. Catching the data can be really useful when you want to get information on the files (what are the codecs, the size of the file, that sort of things).

What would be nice, is to be able to override the "print" and "printErr" callbacks of the module, to catch the output data of ffmpeg. https://emscripten.org/docs/api_reference/module.html

[jeromewu]

May I know the version you are using? This feature has been added in the last few versions of ffmpeg.js.
You can get print and printErr output by assigning logger in createWorker.

Snippet：

const worker = createWorker({
  logger: log => console.log(log),
});

[LucCADORET]

I am actually not using a pure version of @ffmpeg/ffmpeg, I am using a custom worker, along with @ffmpeg/core. I have tried to configure the "Module" directly (overriding Module.print and Module.printErr) without any result. Thanks for the fast reply, I will look into the new version to see how you have done it, and reproduce.

[jeromewu]

Here is the key file for your reference.

https://github.com/ffmpegjs/FFmpeg/blob/n4.1.4-js/javascript/prepend.js

[jeromewu]

Close for now.