What is the closest way to trim the end of the stream returned at a given time, while staying on client side (without using ffmpeg or web assembly solutions)

[mgloc]

Indeed slicing blob end doesn't affect the head keyframe, and then the downloaded resulting file would have incorrect duration

[TheNozomi]

As you can check on this SO answer, you can't simply remove bytes from the video to trim it, you also have to modify the atom headers (that's for mp4, matroska uses a similar structure). Since you don't want to use FFMpeg I guess you're trying to do this process client-side (browser), if so, any reason for not wanting to use wasm?