How to Get FFT of the Wav File?

[kazathul]

Hi there,
I'm trying to get the FFT of a pure tone wav file. I've actually added (overloaded) a function in the clunk::WavFile class like follows:

Sample * WavFile::load(clunk::Buffer &buffer, Context &context, const std::string &fname) {
    FILE *f = fopen(fname.c_str(), "rb");
    if (!f)
        throw std::runtime_error("cannot open file: " + fname);
    WavFile wav(f);
    wav.read();
    std::auto_ptr<Sample> sample(context.create_sample());
    sample->init(wav._data, wav._spec);
    sample->name = fname;
    // Copy the data
    buffer = wav._data;
    return sample.release();
}

And in my main I'm doing something like this:

clunk::Buffer zeBuffer;
clunk::Sample * pureTone = clunk::WavFile::load(zeBuffer, context, "pureTone.wav");

I just want the FFT of the sound file. How can I do it?
I appreciate your help,
Thanks in advance.

[Vladimir Menshakov]

it's as simple as the following code.

fft_context<512> fft;
for(unsigned i = 0; i < 512; ++i)
    //assuming signed 16-bit samples
    //you could always convert raw data via Resample::resample(dst_format, dst_buffer, src_format, src_buffer);
    fft.data[i] = std::complex(samples[i] / 32768.0, 0);

fft.fft();

I don't think you need to override something in wave file. I will add the api for getting raw format/sample data from sample right away :)

Sorry for delay in responses, I was on business trip in Taiwan.

[Vladimir Menshakov]

also you could cast raw sample data via AudioFormat<T> template as follows:

//assuming your data in s16:
assert(sample->get_spec().format == AudioSpec::S16);

typedef AudioFormat<AudioSpec::S16>::Type src_type;
const src_type *src = static_cast< const src_type* >(sample->get_data().get_ptr());

this is the most convenient and fastest way to access raw data.

PS I just added the needed API and removed friend declaration

[kazathul]

I'm also away for a short vacation at the moment.
I'll definitely look into this once I get back this weekend.
Appreciated.