examples/mfcc.js: add mfcc extraction example

diff --git a/examples/mfcc.js b/examples/mfcc.js
new file mode 100644 (file)
index 0000000..b5b40b1
--- /dev/null
+++ b/examples/mfcc.js
@@ -0,0 +1,79 @@
+var aubio = require('../index.js');
+var ref = require('ref');
+
+var extract_mfcc = function(inputfile, params) {
+
+    // open input file for reading
+    var source = aubio.new_aubio_source(inputfile, params.samplerate, params.hop_s);
+    try {
+        source.readPointer();
+    } catch (e) {
+        console.error('failed opening ' + inputfile + ' for reading');
+        return;
+    }
+
+    // get the real samplerate of the input file in case 0 was passed as params.samplerate
+    var samplerate = aubio.aubio_source_get_samplerate(source);
+
+    // open output file for writing
+    var pvoc = aubio.new_aubio_pvoc(params.win_s, params.hop_s);
+    try {
+        pvoc.readPointer();
+    } catch (e) {
+        console.error('failed creating phase vocoder');
+        return; //goto failed_pvoc;
+    }
+
+    // create filter
+    var mfcc = aubio.new_aubio_mfcc(params.win_s, params.n_filters,
+            params.n_coeffs, samplerate);
+    try {
+        mfcc.readPointer();
+    } catch (e) {
+        console.error('failed creating phase vocoder');
+        return; //goto failed_pvoc;
+    }
+
+    // start processing
+    var total_frames = 0;
+    var readPtr = ref.alloc('int');
+    var samples = aubio.new_fvec(params.hop_s);
+    var fftgrain = aubio.new_cvec(params.win_s);
+    var mfcc_out = aubio.new_fvec(params.n_coeffs);
+    while (true) {
+        aubio.aubio_source_do(source, samples, readPtr);
+        aubio.aubio_pvoc_do(pvoc, samples, fftgrain);
+        aubio.aubio_mfcc_do(mfcc, fftgrain, mfcc_out);
+        aubio.fvec_print(mfcc_out);
+        total_frames += readPtr.deref();
+        if (readPtr.deref() != params.hop_s) { break; }
+    }
+    var cur_time = total_frames / samplerate;
+    console.log('read %d seconds (%d samples) from %s', cur_time.toFixed(3),
+            total_frames, inputfile);
+
+    // clean up
+    aubio.del_aubio_mfcc(mfcc);
+    aubio.del_aubio_pvoc(pvoc);
+    aubio.del_aubio_source(source);
+    aubio.del_fvec(samples);
+    aubio.del_cvec(fftgrain);
+    aubio.del_fvec(mfcc_out);
+}
+
+if (process.argv[2]) {
+    var inputfile = process.argv[2];
+} else {
+    console.error('a command line is required.');
+    console.log('usage examples:');
+    console.log('   ' + process.argv[0] + ' ' + process.argv[1] + ' <mediafile>');
+    return;
+}
+
+extract_mfcc(inputfile, {
+    samplerate: 0, // will use input source samplerate
+    win_s : 512,
+    hop_s : 256,
+    n_filters: 40,
+    n_coeffs: 13,
+});