Qt4 and SFML pitch recognition and processing

Question

I am writing a program that displays a random natural note and waits for the user to play that note on the guitar. The audio input is processed to see if the correct pitch was played, and if it was, the next note is shown and the score of the user is updated. The idea is to teach basic guitar notes.

I intend to use SFML for audio processing and QT4 for the gui. I will have a widget derived from the relevant QObject and SFML classes.

Question: How do I detect the pitch of microphone input using SFML? Is it possible to simply store a part of the input in an sf::sound object and call it's getPitch() method?

I've removed qt4 tag as question is not related to it – Kamil Klimek Dec 21 '11 at 08:05 — Kamil Klimek, Dec 21 '11 at 08:05

score 1 · Answer 1 · answered Dec 21 '11 at 12:17

Is it possible to simply store a part of the input in an sf::sound object and call it's getPitch() method?

GetPitch() from sf::SoundSource will return the value you used on SetPitch(pitch) or teh default 1.0f. It is to edit the sound, not to get information about it. I think the only way to do it is to get the array of sound samples and process it with some kind of algorithm. You can get this array with it:

sf::SoundBufferRecorder recorder;
recorder.Start();
// ...
recorder.Stop();
const sf::SoundBuffer& buffer = recorder.GetBuffer();

size_t           sample_count       = buffer.GetSamplesCount();
const sf::Int16* samples            = buffer.GetSamples();
unsigned int     samples_per_second = buffer.GetSampleRate();

Thanks for the input; I found out about FFT's on sound buffers as an indirect result of this. — Adam, Mar 08 '12 at 06:38

score 0 · Accepted Answer · answered Mar 08 '12 at 06:37

As it turns out, SFML does not have any algorithms for detecting pitch built in. Thanks to LBg for getting my mind working in the right direction. SFML only provides the tools needed to record the sounds and store them in a buffer.

I found out that I can use a Fast Fourier transform to evaluate the buffer for a frequency. This frequency can then be compared to a list of known pitch frequencies, together with a pitch threshold.

While SFML doesn't have an fft algorithm built in, it does have the tools needed to get a sound buffer. I will have to check and see if this is the most cross-platform way of doing things.

Qt4 and SFML pitch recognition and processing

2 Answers2