问题
As a result of the answer here: Recording cross-platform (H.264?) videos using WebRTC MediaRecorder
How can one go about using ffmpeg.js to efficiently unwrap a webm h.264 video and re-wrap it into an mp4 container?
I'm looking through the docs: https://github.com/Kagami/ffmpeg.js?files=1
However I don't see (or perhaps I'm looking for the wrong terminology) any examples for the above. This operation will be performed on the browser (chrome) prior to uploading as a Blob - I could use a web worker though hopefully rewrapping is a trivial enough operation to not require it.
来源：https://stackoverflow.com/questions/45417952/convert-webm-h-264-to-mp4-h-264-efficiently-with-ffmpeg-js