1 files changed, 110 insertions, 0 deletions
diff --git a/src/dywapitchtrack/dywapitchtrack.h b/src/dywapitchtrack/dywapitchtrack.h
new file mode 100755
index 0000000..0c12f80
--- /dev/null
+++ b/src/dywapitchtrack/dywapitchtrack.h
@@ -0,0 +1,110 @@
+/* dywapitchtrack.h
+ 
+ Dynamic Wavelet Algorithm Pitch Tracking library
+ Released under the MIT open source licence
+ 
+ Copyright (c) 2010 Antoine Schmitt
+  
+ Permission is hereby granted, free of charge, to any person obtaining a copy
+ of this software and associated documentation files (the "Software"), to deal
+ in the Software without restriction, including without limitation the rights
+ to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ copies of the Software, and to permit persons to whom the Software is
+ furnished to do so, subject to the following conditions:
+ 
+ The above copyright notice and this permission notice shall be included in
+ all copies or substantial portions of the Software.
+ 
+ THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ THE SOFTWARE.
+*/
+
+/* Documentation
+ 
+ The dywapitchtrack library computes the pitch of an audio stream in real time.
+ 
+ The pitch is the main frequency of the waveform (the 'note' being played or sung).
+ It is expressed as a float in Hz.
+ 
+ Unlike the human ear, pitch detection is difficult to achieve for computers. Many
+ algorithms have been designed and experimented, but there is no 'best' algorithm.
+ They all depend on the context and the tradeoffs acceptable in terms of speed and
+ latency. The context includes the quality and 'cleanness' of the audio : obviously
+ polyphonic sounds (multiple instruments playing different notes at the same time)
+ are extremely difficult to track, percussive or noisy audio has no pitch, most
+ real-life audio have some noisy moments, some instruments have a lot of harmonics,
+ etc...
+ 
+ The dywapitchtrack is based on a custom-tailored algorithm which is of very high quality:
+ both very accurate (precision < 0.05 semitones), very low latency (< 23 ms) and
+ very low error rate. It has been  thoroughly tested on human voice.
+ 
+ It can best be described as a dynamic wavelet algorithm (dywa):
+ 
+ The heart of the algorithm is a very powerful wavelet algorithm, described in a paper
+ by Eric Larson and Ross Maddox : "Real-Time Time-Domain Pitch Tracking Using Wavelets"
+ http://online.physics.uiuc.edu/courses/phys498pom/NSF_REU_Reports/2005_reu/Real-Time_Time-Domain_Pitch_Tracking_Using_Wavelets.pdf
+ 
+ This central algorithm has been improved by adding dynamic tracking, to reduce the
+ common problems of frequency-halving and voiced/unvoiced errors. This dynamic tracking
+ explains the need for a tracking structure (dywapitchtracker). The dynamic tracking assumes
+ that the main function dywapitch_computepitch is called repeatedly, as it follows the pitch
+ over time and makes assumptions about human voice capabilities and reallife conditions
+ (as documented inside the code).
+ 
+ Note : The algorithm currently assumes a 44100Hz audio sampling rate. If you use a different
+ samplerate, you can just multiply the resulting pitch by the ratio between your samplerate and 44100.
+*/
+
+/* Usage
+
+ // Allocate your audio buffers and start the audio stream.
+ // Allocate a 'dywapitchtracker' structure.
+ // Start the pitch tracking by calling 'dywapitch_inittracking'.
+ dywapitchtracker pitchtracker;
+ dywapitch_inittracking(&pitchtracker);
+ 
+ // For each available audio buffer, call 'dywapitch_computepitch'
+ double thepitch = dywapitch_computepitch(&pitchtracker, samples, start, count);
+ 
+*/
+
+#ifndef dywapitchtrack__H
+#define dywapitchtrack__H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+// structure to hold tracking data
+typedef struct _dywapitchtracker {
+	double	_prevPitch;
+	int		_pitchConfidence;
+} dywapitchtracker;
+
+// returns the number of samples needed to compute pitch for fequencies equal and above the given minFreq (in Hz)
+// useful to allocate large enough audio buffer 
+// ex : for frequencies above 130Hz, you need 1024 samples (assuming a 44100 Hz samplerate)
+int dywapitch_neededsamplecount(int minFreq);
+
+// call before computing any pitch, passing an allocated dywapitchtracker structure
+void dywapitch_inittracking(dywapitchtracker *pitchtracker);
+
+// computes the pitch. Pass the inited dywapitchtracker structure
+// samples : a pointer to the sample buffer
+// startsample : the index of teh first sample to use in teh sample buffer
+// samplecount : the number of samples to use to compte the pitch
+// return 0.0 if no pitch was found (sound too low, noise, etc..)
+double dywapitch_computepitch(dywapitchtracker *pitchtracker, double * samples, int startsample, int samplecount);
+
+#ifdef __cplusplus
+} // extern "C"
+#endif
+
+#endif
+