How to get Beats per minutes of a song in objective-c

Question

I did lots of R&D but did not get any good answer. I am working on music type app in iphone and i have to categorized songs on the basis of beats per minute.So my first task

Answer 1

You can use http://www.un4seen.com/ for detecting BPM of song.

Here is code for calculating BPM using this library.

HSTREAM mainStream = BASS_StreamCreateFile(FALSE,[pathStr UTF8String],0,0,BASS_SAMPLE_FLOAT|BASS_STREAM_PRESCAN|BASS_STREAM_DECODE);

float playBackDuration=BASS_ChannelBytes2Seconds(mainStream, BASS_ChannelGetLength(mainStream, BASS_POS_BYTE));

HSTREAM  bpmStream=BASS_StreamCreateFile(FALSE, [pathStr UTF8String], 0, 0, BASS_STREAM_PRESCAN|BASS_SAMPLE_FLOAT|BASS_STREAM_DECODE);

float BpmValue= BASS_FX_BPM_DecodeGet(
                                bpmStream,
                                0.00,
                                playBackDuration,
                                MAKELONG(45,256),
                                BASS_FX_BPM_MULT2,
                                 NULL);


    //Check if BpmValue have any value or not.
    //If it haven't any value then set default value to 128.
    if(BpmValue<=0)
          BpmValue = 128.00;

You can do many other things like scratching using this library.