def silenceRemoval(x, Fs, stWin, stStep, smoothWindow = 0.5, Weight = 0.5, plot = False):
'''
Event Detection (silence removal)
ARGUMENTS:
- x: the input audio signal
- Fs: sampling freq
- stWin, stStep: window size and step in seconds
- smoothWindow: (optinal) smooth window (in seconds)
- Weight: (optinal) weight factor (0 < Weight < 1) the higher, the more strict
- plot: (optinal) True if results are to be plotted
RETURNS:
- segmentLimits: list of segment limits in seconds (e.g [[0.1, 0.9], [1.4, 3.0]] means that
the resulting segments are (0.1 - 0.9) seconds and (1.4, 3.0) seconds
'''
if Weight>=1:
Weight = 0.99;
if Weight<=0:
Weight = 0.01;
# Step 1: feature extraction
x = audioBasicIO.stereo2mono(x); # convert to mono
ShortTermFeatures = aF.stFeatureExtraction(x, Fs, stWin*Fs, stStep*Fs) # extract short-term features
# Step 2: train binary SVM classifier of low vs high energy frames
EnergySt = ShortTermFeatures[1, :] # keep only the energy short-term sequence (2nd feature)
E = numpy.sort(EnergySt) # sort the energy feature values:
L1 = int(len(E)/10) # number of 10% of the total short-term windows
T1 = numpy.mean(E[0:L1]) # compute "lower" 10% energy threshold
T2 = numpy.mean(E[-L1:-1]) # compute "higher" 10% energy threshold
Class1 = ShortTermFeatures[:,numpy.where(EnergySt<T1)[0]] # get all features that correspond to low energy
Class2 = ShortTermFeatures[:,numpy.where(EnergySt>T2)[0]] # get all features that correspond to high energy
featuresSS = [Class1.T, Class2.T]; # form the binary classification task and ...
[featuresNormSS, MEANSS, STDSS] = aT.normalizeFeatures(featuresSS) # normalize and ...
SVM = aT.trainSVM(featuresNormSS, 1.0) # train the respective SVM probabilistic model (ONSET vs SILENCE)
# Step 3: compute onset probability based on the trained SVM
ProbOnset = []
for i in range(ShortTermFeatures.shape[1]): # for each frame
curFV = (ShortTermFeatures[:,i] - MEANSS) / STDSS # normalize feature vector
ProbOnset.append(SVM.pred_probability(curFV)[1]) # get SVM probability (that it belongs to the ONSET class)
ProbOnset = numpy.array(ProbOnset)
ProbOnset = smoothMovingAvg(ProbOnset, smoothWindow / stStep) # smooth probability
# Step 4A: detect onset frame indices:
ProbOnsetSorted = numpy.sort(ProbOnset) # find probability Threshold as a weighted average of top 10% and lower 10% of the values
Nt = ProbOnsetSorted.shape[0] / 10;
T = (numpy.mean( (1-Weight)*ProbOnsetSorted[0:Nt] ) + Weight*numpy.mean(ProbOnsetSorted[-Nt::]) )
MaxIdx = numpy.where(ProbOnset>T)[0]; # get the indices of the frames that satisfy the thresholding
i = 0;
timeClusters = []
segmentLimits = []
# Step 4B: group frame indices to onset segments
while i<len(MaxIdx): # for each of the detected onset indices
curCluster = [MaxIdx[i]]
if i==len(MaxIdx)-1:
break
while MaxIdx[i+1] - curCluster[-1] <= 2:
curCluster.append(MaxIdx[i+1])
i += 1
if i==len(MaxIdx)-1:
break
i += 1
timeClusters.append(curCluster)
segmentLimits.append([curCluster[0]*stStep, curCluster[-1]*stStep])
# Step 5: Post process: remove very small segments:
minDuration = 0.2;
segmentLimits2 = []
for s in segmentLimits:
if s[1] - s[0] > minDuration:
segmentLimits2.append(s)
segmentLimits = segmentLimits2;
if plot:
timeX = numpy.arange(0, x.shape[0] / float(Fs) , 1.0/Fs)
plt.subplot(2,1,1); plt.plot(timeX, x)
for s in segmentLimits:
plt.axvline(x=s[0]);
plt.axvline(x=s[1]);
plt.subplot(2,1,2); plt.plot(numpy.arange(0, ProbOnset.shape[0] * stStep, stStep), ProbOnset);
plt.title('Signal')
for s in segmentLimits:
plt.axvline(x=s[0]);
plt.axvline(x=s[1]);
plt.title('SVM Probability')
plt.show()
return segmentLimits
def silenceRemoval(x,
fs,
st_win,
st_step,
smoothWindow=0.5,
weight=0.5,
plot=False):
'''
Event Detection (silence removal)
ARGUMENTS:
- x: the input audio signal
- fs: sampling freq
- st_win, st_step: window size and step in seconds
- smoothWindow: (optinal) smooth window (in seconds)
- weight: (optinal) weight factor (0 < weight < 1) the higher, the more strict
- plot: (optinal) True if results are to be plotted
RETURNS:
- seg_limits: list of segment limits in seconds (e.g [[0.1, 0.9], [1.4, 3.0]] means that
the resulting segments are (0.1 - 0.9) seconds and (1.4, 3.0) seconds
'''
if weight >= 1:
weight = 0.99
if weight <= 0:
weight = 0.01
# Step 1: feature extraction
x = audioBasicIO.stereo2mono(x)
st_feats, _ = aF.stFeatureExtraction(x, fs, st_win * fs, st_step * fs)
# Step 2: train binary svm classifier of low vs high energy frames
# keep only the energy short-term sequence (2nd feature)
st_energy = st_feats[1, :]
en = numpy.sort(st_energy)
# number of 10% of the total short-term windows
l1 = int(len(en) / 10)
# compute "lower" 10% energy threshold
t1 = numpy.mean(en[0:l1]) + 0.000000000000001
# compute "higher" 10% energy threshold
t2 = numpy.mean(en[-l1:-1]) + 0.000000000000001
# get all features that correspond to low energy
class1 = st_feats[:, numpy.where(st_energy <= t1)[0]]
# get all features that correspond to high energy
class2 = st_feats[:, numpy.where(st_energy >= t2)[0]]
# form the binary classification task and ...
faets_s = [class1.T, class2.T]
# normalize and train the respective svm probabilistic model
# (ONSET vs SILENCE)
[faets_s_norm, means_s, stds_s] = aT.normalizeFeatures(faets_s)
svm = aT.trainSVM(faets_s_norm, 1.0)
# Step 3: compute onset probability based on the trained svm
prob_on_set = []
for i in range(st_feats.shape[1]):
# for each frame
cur_fv = (st_feats[:, i] - means_s) / stds_s
# get svm probability (that it belongs to the ONSET class)
prob_on_set.append(svm.predict_proba(cur_fv.reshape(1, -1))[0][1])
prob_on_set = numpy.array(prob_on_set)
# smooth probability:
prob_on_set = smoothMovingAvg(prob_on_set, smoothWindow / st_step)
# Step 4A: detect onset frame indices:
prog_on_set_sort = numpy.sort(prob_on_set)
# find probability Threshold as a weighted average
# of top 10% and lower 10% of the values
Nt = int(prog_on_set_sort.shape[0] / 10)
T = (numpy.mean((1 - weight) * prog_on_set_sort[0:Nt]) +
weight * numpy.mean(prog_on_set_sort[-Nt::]))
max_idx = numpy.where(prob_on_set > T)[0]
# get the indices of the frames that satisfy the thresholding
i = 0
time_clusters = []
seg_limits = []
# Step 4B: group frame indices to onset segments
while i < len(max_idx):
# for each of the detected onset indices
cur_cluster = [max_idx[i]]
if i == len(max_idx) - 1:
break
while max_idx[i + 1] - cur_cluster[-1] <= 2:
cur_cluster.append(max_idx[i + 1])
i += 1
if i == len(max_idx) - 1:
break
i += 1
time_clusters.append(cur_cluster)
seg_limits.append(
[cur_cluster[0] * st_step, cur_cluster[-1] * st_step])
# Step 5: Post process: remove very small segments:
min_dur = 0.2
seg_limits_2 = []
for s in seg_limits:
if s[1] - s[0] > min_dur:
seg_limits_2.append(s)
seg_limits = seg_limits_2
if plot:
timeX = numpy.arange(0, x.shape[0] / float(fs), 1.0 / fs)
plt.subplot(2, 1, 1)
plt.plot(timeX, x)
for s in seg_limits:
plt.axvline(x=s[0])
plt.axvline(x=s[1])
plt.subplot(2, 1, 2)
plt.plot(numpy.arange(0, prob_on_set.shape[0] * st_step, st_step),
prob_on_set)
plt.title('Signal')
for s in seg_limits:
plt.axvline(x=s[0])
plt.axvline(x=s[1])
plt.title('svm Probability')
plt.show()
return seg_limits
