What is the best audio file format to stream on both iPhone and Android

Question

My client do have 10000+ audio songs on a server, he does want to develop an iPhone and Android app to play those songs. He is willing to convert the audio files for any given format.

So what is the best format store those files on the server to consume in iOS and Android ?

Answer 1

OGG is the best I've used so far on both Android and iOS.

Here's the list of libraries for this for other platforms as well.