Sound convertion to frequency in android [duplicate]

Answer 1

You will need a pitch estimation algorithm (there have been many published, such as autocorrelation, ASDF/AMDF, cepstral processing, harmonic product spectrum, RAPT, YAAPT, etc.). Frequency estimation alone is not suitable for guitar tuning, as note pitch is different from spectral frequency.

Answer 2

EDIT: link dead ---This problem is already solved here---

I shall summarize the paper :

1. Record stuff :

       int minSize = AudioRecord.getMinBufferSize(sampleRate,AudioFormat.
       CHANNEL_CONFIGURATION_MONO,
       AudioFormat.ENCODING_PCM_16BIT);
       AudioRecord audioInput = new AudioRecord(MediaRecorder.AudioSource.MIC, sampleRate,
       AudioFormat.CHANNEL_CONFIGURATION_MONO,
       AudioFormat.ENCODING_PCM_16BIT);
       minSize);
       ...
       short[] buffer = new short[readSize];
       audioInput.startRecording();
       audioInput.read(buffer, index, readSize); // record data from mic into buffer
   

2. Anayze the frequency using FFT.

I'd say you record about 4 seconds of apply FFT on it. Like hotpaw2 says you have to use pitch estimation algorithms to determine the range of frequencies in recorded sound from the strum.