How to lower the bitrate of mp3 in iOS?

Question

I made a Multipeer Audio Streaming app using the Tony's tutorial. But I can only play .mp3 with 128kbps bit rate. So I need to lower .mp3 with 192kbps or more bit rate to 128kbps. I found a similar solution[here], but it's for encoding mp3 to video.

Please help me how to lower the bitrate.

Answer 1

AVAssetReaderTrackOutput *assetOutput = [AVAssetReaderTrackOutput assetReaderTrackOutputWithTrack:asset.tracks[0] outputSettings:nil];  

You should provide outputSettings: on a server side (phone that streams audio)

So it should look like this.

NSDictionary *settings = @{
    AVEncoderBitRateKey : @128000,
    AVFormatIDKey : @(kAudioFormatAppleIMA4),
    AVNumberOfChannelsKey : @2,
    AVLinearPCMBitDepthKey : @16,
    AVLinearPCMIsBigEndianKey : @NO,
    AVLinearPCMIsFloatKey : @NO
};
AVAssetReaderTrackOutput *assetOutput = [AVAssetReaderTrackOutput assetReaderTrackOutputWithTrack:asset.tracks[0] outputSettings:settings];