6.1 beta version is now opening 3gp files. They would have to be selected from "Choose a File" picker, as the other options are limited to what the what the system considers audio files.
There is no way to do it, though you may be able to find old versions at sites that cache old versions of apps. However, I think I addressed your concern from your other posts.
The feature is still there, in Settings. It's moved there because before people would hit it by accident, and think the independent control had been removed permanently (?)
Hello. Perhaps you were used to artifacts that the other libraries added to the signal. Before it was decided to use elastique we A/B'd extensively with the old libraries. It has significantly less coloration of the sound in most cases than Superpow…
Hello, it would do this for mp3's which are encoded with MPEG-2 Audio Layer III, they would typically be mp3's with a low sampling rate such as 16000 Hz, 22050 Hz or 24000 Hz or low kbps. It did this for the Superpowered engine in previous versions …
Beta 6.0 is 8MB download, it has some unused libraries, I believe it can be reduced by 1-2 MB, but no more. There is a lot that goes into it such as a separate decoder/demuxer for each of the many file types it can open.
Opus and mp4 files will open from the "Choose a File" dialog in 6.1 beta version. The other options in the side menu won't let you select them because they're limited to what the system considers audio files.
The beta version exports to MP3, changed from m4a because many people requested. Wav option is possibility, it will export really fast too, encoding to lossy format is what takes the most time.