Hi, it depends a bit, if the mp3 stream uses bit reservoir it might be tricky to to "pure" remuxing with any tool. fq:s mp3_frame decoder do try to know what bits are parts of the current frame or part of a future frame but not sure how much that helps. If the stream does not use reservoir you should be able to slice using fq '.frames[100:200][]' file.mp3 > sliced.mp3 or something similar.
