FFmpeg save stream to mp3

Question

I have an iOS project that play online radio streams, it is use FFmpeg to play. Also I added ability to record streams, decode streams via avcodec_decode_audio4 function, and write output to .wav file. But this files are too big, because it is uncompressed format, so I want to decode files to .mp3 .

I have found couple ways to convert audio but only when audio it is ready file, but I want decode to some compressed format as soon as I get chunk of data from stream, not ready file.

Is it possible? Can you give me some advise how to achieve this?

Answer 1

You can use ffmpeg (aka libav) to encode the audio you're reading with avcodec_decode_audio4 into a file as mp3, as long as libav was configured with lame ( --enable-libmp3lame ).

Basically, you configure an mp3 codec, then call avcodec_encode_audio2 (who names these things?) on the progressive output of avcodec_decode_audio4 .

The canonical example can be confusing because it also deals with video, but you should be able to tease the details you want out of it.

This post on transcoding audio by arashafiei is broadly helpful.