@sunnyday07

Hi

Assuming your requirement is a smaller file size:

1. The file type is to some extent only relevant in terms the degree of support for the format used, ie how universal the format is required to be for playback on different devices.
    
2. The major determinants of file size are, in decreasing order of effect, Bitrate, Samplerate and to a small extent bit depth.

My recommendation would be use the audio file type that meets point 1, then carry out a series of tests adjusting (lowering) the Samplerate first to get it down to a usable level, then adjust (lower) the Bitrate, to the lowest level that the audio still remains usable.

This is a balancing act between Bitrate and Samplerate to maintain a usable audio file, getting 'one size fits all' balance btween the 2 parameters may/may-not difficult depending on the audio content.

HTH

John EB
Forum Moderator