examples/source_reader.js: added a simple source reader

diff --git a/examples/source_reader.js b/examples/source_reader.js
new file mode 100644 (file)
index 0000000..b5f8213
--- /dev/null
+++ b/examples/source_reader.js
@@ -0,0 +1,46 @@
+var aubio = require('../');
+var ref = require('ref');
+
+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;
+}
+
+var samplerate = 0; // this tells aubio_source to use test.wav samplerate
+var hop_s = 512; // number of samples to be read at each aubio_source_do call
+
+var source = aubio.new_aubio_source(inputfile, samplerate, hop_s);
+try {
+  source.readPointer();
+} catch (e) {
+  console.error('failed opening ' + inputfile + ' for reading');
+  return;
+}
+// get the actual samplerate of the input file
+var samplerate = aubio.aubio_source_get_samplerate(source);
+
+var readPtr = ref.alloc('int'); // a pointer to and int
+var total_frames = 0; // frame counter
+
+var samples = aubio.new_fvec(hop_s);
+while (true) {
+  // read at most hop_s frames from inputfile
+  aubio.aubio_source_do(source, samples, readPtr);
+  // increment the number of frames read
+  total_frames += readPtr.deref();
+  // stop at end of file
+  if (readPtr.deref() != hop_s) { break; }
+}
+// compute the duration in seconds
+var cur_time = total_frames / samplerate;
+// print duration and number of frames read
+console.log('read %d seconds (%d frames) from %s', cur_time.toFixed(3),
+    total_frames, inputfile);
+
+// clean up memory (each new_ should have a corresponding del_)
+aubio.del_aubio_source(source);
+aubio.del_fvec(samples);