first commit

README

@@ -0,0 +1,5 @@
+This is Paulstretch , Python version
+by Nasca Octavian PAUL, Targu Mures, Romania
+
+Requirements: Numpy, Scipy
+

paulstretch_stereo.py

@@ -0,0 +1,149 @@
+#!/usr/bin/env python
+#
+# Paul's Extreme Sound Stretch (Paulstretch) - Python version
+#
+# by Nasca Octavian PAUL, Targu Mures, Romania
+#
+# http://hypermammut.sourceforge.net/paulstretch/
+#
+#
+
+
+import sys
+from numpy import *
+import scipy.io.wavfile
+import wave
+from optparse import OptionParser
+
+def load_wav(filename):
+    try:
+        wavedata=scipy.io.wavfile.read(filename)
+        samplerate=int(wavedata[0])
+        smp=wavedata[1]*(1.0/32768.0)
+        smp=smp.transpose()
+        if len(smp.shape)==1: #convert to stereo
+            smp=tile(smp,(2,1))
+        return (samplerate,smp)
+    except:
+        print "Error loading wav: "+filename
+        return None
+
+
+
+def optimize_windowsize(n):
+    orig_n=n
+    while True:
+        n=orig_n
+        while (n%2)==0:
+            n/=2
+        while (n%3)==0:
+            n/=3
+        while (n%5)==0:
+            n/=5
+
+        if n<2:
+            break
+        orig_n+=1
+    return orig_n
+
+def paulstretch(samplerate,smp,stretch,windowsize_seconds,outfilename):
+    nchannels=smp.shape[0]
+
+    outfile=wave.open(outfilename,"wb")
+    outfile.setsampwidth(2)
+    outfile.setframerate(samplerate)
+    outfile.setnchannels(nchannels)
+
+    #make sure that windowsize is even and larger than 16
+    windowsize=int(windowsize_seconds*samplerate)
+    if windowsize<16:
+        windowsize=16
+    windowsize=optimize_windowsize(windowsize)
+    windowsize=int(windowsize/2)*2
+    half_windowsize=int(windowsize/2)
+
+    #correct the end of the smp
+    nsamples=smp.shape[1]
+    end_size=int(samplerate*0.05)
+    if end_size<16:
+        end_size=16
+
+    smp[:,nsamples-end_size:nsamples]*=linspace(1,0,end_size)
+
+
+    #compute the displacement inside the input file
+    start_pos=0.0
+    displace_pos=(windowsize*0.5)/stretch
+
+    #create Hann window
+    window=0.5-cos(arange(windowsize,dtype='float')*2.0*pi/(windowsize-1))*0.5
+
+    old_windowed_buf=zeros((2,windowsize))
+    hinv_sqrt2=(1+sqrt(0.5))*0.5
+    hinv_buf=(hinv_sqrt2-(1.0-hinv_sqrt2)*cos(arange(half_windowsize,dtype='float')*2.0*pi/half_windowsize))/hinv_sqrt2
+
+    while True:
+        #get the windowed buffer
+        istart_pos=int(floor(start_pos))
+        buf=smp[:,istart_pos:istart_pos+windowsize]
+        if buf.shape[1]<windowsize:
+            buf=append(buf,zeros((2,windowsize-buf.shape[1])),1)
+        buf=buf*window
+
+        #get the amplitudes of the frequency components and discard the phases
+        freqs=abs(fft.rfft(buf))
+
+        #randomize the phases by multiplication with a random complex number with modulus=1
+        ph=random.uniform(0,2*pi,(nchannels,freqs.shape[1]))*1j
+        freqs=freqs*exp(ph)
+
+        #do the inverse FFT 
+        buf=fft.irfft(freqs)
+
+        #window again the output buffer
+        buf*=window
+
+        #overlap-add the output
+        output=buf[:,0:half_windowsize]+old_windowed_buf[:,half_windowsize:windowsize]
+        old_windowed_buf=buf
+
+        #remove the resulted amplitude modulation
+        output*=hinv_buf
+
+        #clamp the values to -1..1 
+        output[output>1.0]=1.0
+        output[output<-1.0]=-1.0
+
+        #write the output to wav file
+        outfile.writeframes(int16(output.ravel(1)*32767.0).tostring())
+
+        start_pos+=displace_pos
+        if start_pos>=nsamples:
+            print "100 %"
+            break
+        print "%d %% \r" % int(100.0*start_pos/nsamples),
+        sys.stdout.flush()
+
+    outfile.close()
+
+########################################
+print "Paul's Extreme Sound Stretch (Paulstretch) - Python version 20110219"
+print "by Nasca Octavian PAUL, Targu Mures, Romania\n"
+parser = OptionParser(usage="usage: %prog [options] input_wav output_wav")
+parser.add_option("-s", "--stretch", dest="stretch",help="stretch amount (1.0 = no stretch)",type="float",default=8.0)
+parser.add_option("-w", "--window_size", dest="window_size",help="window size (seconds)",type="float",default=0.25)
+(options, args) = parser.parse_args()
+
+
+if (len(args)<2) or (options.stretch<=0.0) or (options.window_size<=0.001):
+    print "Error in command line parameters. Run this program with --help for help."
+    sys.exit(1)
+
+print "stretch amount =",options.stretch
+print "window size =",options.window_size,"seconds"
+(samplerate,smp)=load_wav(args[0])
+
+paulstretch(samplerate,smp,options.stretch,options.window_size,args[1])
+
+
+