Azahar-Mirror/soundtouch
1
0
Fork 0
mirror of https://github.com/azahar-emu/soundtouch synced 2025-11-07 15:40:04 +01:00
Code Issues Packages Projects Releases Wiki Activity

Added automatic cutoff threshold adaptation to beat detection routine to better adapt BPM calculation to different types of music

Browse Source
This commit is contained in:
oparviai 2010-01-06 18:59:23 +00:00
parent 3dbc7209bd
commit ff06c88fd5
4 changed files with 68 additions and 13 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

19
README.html
View File

@ -18,7 +18,7 @@
</head>
<body class="normal">
<hr>
<h1>SoundTouch audio processing library v1.5.0
<h1>SoundTouch audio processing library v1.5.1pre
</h1>
<p class="normal">SoundTouch library Copyright &copy; Olli
Parviainen 2001-2009 </p>
@ -536,6 +536,13 @@ estimates the BPM rate:</p>
<h2>5. Change History</h2>
<h3>5.1. SoundTouch library Change History </h3>
<p><b>1.5.1pre:</b></p>
<ul>
<li>Added automatic cutoff threshold adaptation to beat detection routine to
better adapt BPM calculation&nbsp; to different types of music</li>
</ul>
<p><strong>1.5.0:</strong></p>
<ul>
<li>Added normalization to correlation calculation and improvement automatic seek/sequence parameter calculation to improve sound quality</li>
@ -657,7 +664,15 @@ files. </li>
<h3>5.2. SoundStretch application Change
History </h3>
<p><strong>1.4.0:</strong></p>
<p><b>v1.5.0:</b></p>
<ul>
<li>Added &quot;-speech&quot; switch to activate algorithm parameters more
suitable for speech processing than the default parameters tuned for music
processing.</li>
</ul>
<p><strong>v1.4.0:</strong></p>
<ul>
<li>Moved BPM detection routines from SoundStretch application into SoundTouch
library</li>

13
include/BPMDetect.h
View File

@ -78,10 +78,19 @@ protected:
float *xcorr;
/// Amplitude envelope sliding average approximation level accumulator
float envelopeAccu;
double envelopeAccu;
/// RMS volume sliding average approximation level accumulator
float RMSVolumeAccu;
double RMSVolumeAccu;
/// Level below which to cut off signals
double cutCoeff;
/// Accumulator for accounting what proportion of samples exceed cutCoeff level
double aboveCutAccu;
/// Accumulator for total samples to calculate proportion of samples that exceed cutCoeff level
double totalAccu;
/// Sample average counter.
int decimateCount;

4
include/SoundTouch.h
View File

@ -79,10 +79,10 @@ namespace soundtouch
{
/// Soundtouch library version string
#define SOUNDTOUCH_VERSION "1.5.0"
#define SOUNDTOUCH_VERSION "1.5.1pre"
/// SoundTouch library version id
#define SOUNDTOUCH_VERSION_ID (10500)
#define SOUNDTOUCH_VERSION_ID (10509)
//
// Available setting IDs for the 'setSetting' & 'get_setting' functions:

45
source/SoundTouch/BPMDetect.cpp
View File

@ -96,6 +96,10 @@ BPMDetect::BPMDetect(int numChannels, int aSampleRate)
RMSVolumeAccu = (0.092f * 0.092f) / avgnorm;
#endif
cutCoeff = 1.75;
aboveCutAccu = 0;
totalAccu = 0;
// choose decimation factor so that result is approx. 500 Hz
decimateBy = sampleRate / 500;
assert(decimateBy > 0);
@ -215,16 +219,15 @@ void BPMDetect::updateXCorr(int process_samples)
}
// Calculates envelope of the sample data
void BPMDetect::calcEnvelope(SAMPLETYPE *samples, int numsamples)
{
const float decay = 0.7f; // decay constant for smoothing the envelope
const float norm = (1 - decay);
const static double decay = 0.7f; // decay constant for smoothing the envelope
const static double norm = (1 - decay);
int i;
LONG_SAMPLETYPE out;
float val;
double val;
for (i = 0; i < numsamples; i ++)
{
@ -233,10 +236,32 @@ void BPMDetect::calcEnvelope(SAMPLETYPE *samples, int numsamples)
val = (float)fabs((float)samples[i]);
RMSVolumeAccu += val * val;
// cut amplitudes that are below 2 times average RMS volume
// cut amplitudes that are below cutoff ~2 times RMS volume
// (we're interested in peak values, not the silent moments)
val -= 2 * (float)sqrt(RMSVolumeAccu * avgnorm);
val = (val > 0) ? val : 0;
val -= cutCoeff * sqrt(RMSVolumeAccu * avgnorm);
if (val > 0)
{
aboveCutAccu += 1.0; // sample above threshold
}
else
{
val = 0;
}
totalAccu += 1.0;
// maintain sliding statistic what proportion of 'val' samples is
// above cutoff threshold
aboveCutAccu *= 0.99931; // 2 sec time constant
totalAccu *= 0.99931;
if (totalAccu > 500)
{
// after initial settling, auto-adjust cutoff level so that ~8% of
// values are above the threshold
double d = (aboveCutAccu / totalAccu) - 0.08;
cutCoeff += 0.001 * d;
}
// smooth amplitude envelope
envelopeAccu *= decay;
@ -249,6 +274,12 @@ void BPMDetect::calcEnvelope(SAMPLETYPE *samples, int numsamples)
#endif // INTEGER_SAMPLES
samples[i] = (SAMPLETYPE)out;
}
// check that cutoff doesn't get too small - it can be just silent sequence!
if (cutCoeff < 1.5)
{
cutCoeff = 1.5;
}
}