AudioFeatUreExtractor
流线音频功能提取
描述
AudioFeatUreExtractorencapsulates multiple audio feature extractors into a streamlined and modular implementation.
Creation
描述
AFE= AudioFeatUreExtractor（)
AFE= AudioFeatUreExtractor（名称，价值)AFE使用一个或多个名称值对参数。
Properties
对象功能
extract |
Extract audio features |
setExtractorParams |
设置单个特征提取器的非默认参数值 |
info |
Output mapping and individual feature extractor parameters |
generatematlabfunction |
CreateMATLABfunction compatible with C/C++ code generation |
例子
提取多个音频功能
Read in an audio signal.
[audioIn, fs] = audioread (“计数16-44p1-mono-15secs.wav”）；
Create anAudioFeatUreExtractorobject that extracts the MFCC, delta MFCC, delta-delta MFCC, pitch, and spectral centroid of an audio signal. Use a 30 ms analysis window with 20 ms overlap.
AFE= AudioFeatUreExtractor（。。。“采样率”，fs，。。。"Window",hamming(round(0.03*fs),"periodic"），。。。"OverlapLength"，圆形（0.02*fs），。。。"mfcc",true,。。。"mfccDelta",true,。。。“ mfccdeltadelta”,true,。。。"pitch",true,。。。"spectralCentroid"，真的）;
Callextract从音频信号中提取音频功能。
features = extract(aFE,audioIn);
利用info确定特征提取矩阵的哪一列对应于请求的沥青提取。
idx = info（afe）
idx =带有字段的结构：MFCC：[1 2 3 4 5 6 7 8 9 10 11 12 13] MFCCDELTA：[14 15 16 17 18 19 20 20 21 22 23 24 25 26] MFCCDELTADELTA：[27 28 29 30 30 30 30 31 32 33 33 34 35 36 37 38 38 39 39 39 39 39]光谱中心：40音高：41
Plot the detected pitch over time.
t = linspace（0，大小（Audioin，1）/fs，size（功能，1））;绘图（t，功能（：，idx.pitch））标题（'Pitch') xlabel(“时间）”）ylabel（“频率（Hz）”)
从数据集提取功能
Create an audio datastore that points to audio samples included with Audio Toolbox®.
文件夹= fullfile（matlabroot，'工具箱','audio','samples'）；ads = audioDatastore(folder);
查找对应于44.1 kHz的样本率的所有文件，然后子集the datastore.
keepFile = cellfun(@(x)contains(x,'44p1'），ads.Files); ads = subset(ads,keepFile);
将数据转换为tall大批。tallarrays are evaluated only when you request them explicitly usinggather。MATLAB® automatically optimizes the queued calculations by minimizing the number of passes through the data. If you have Parallel Computing Toolbox™, you can spread the calculations across multiple machines. The audio data is represented as anM-经过-1 tall cell array, whereMis the number of files in the audio datastore.
adsTall = tall(ads)
Starting parallel pool (parpool) using the 'local' profile ... Connected to the parallel pool (number of workers: 6). adsTall = M×1 tall cell array { 539648×1 double} { 227497×1 double} { 8000×1 double} { 685056×1 double} { 882688×2 double} {1115760×2 double} { 505200×2 double} {3195904×2 double} : : : :
Create anAudioFeatUreExtractor从每个音频文件中提取MEL频谱，树皮光谱，ERB频谱和线性频谱。为频谱提取使用默认分析窗口和重叠长度。
AFE= AudioFeatUreExtractor（'SampleRate',44.1e3,。。。'melSpectrum',true,。。。'Barkspectrum',true,。。。'erbSpectrum',true,。。。'linearSpectrum'，真的）;
Define aCellFunfunction so that audio features are extracted from each cell of the tall array. Callgatherto evaluate the tall array.
specstall = cellfun（@（x）提取（afe，x），adstall，"UniformOutput"，错误的）;specs = chater（specstall）;
使用平行池“本地”评估高表情： - 1 of 1：完成在12秒内完成的评估，在12秒内完成
这specs从收集返回的变量是numFiles-经过-1 cell array, wherenumFilesis the number of files in the datastore. Each element of the cell array is anumhops-经过-numFeatures-经过-数字数组，其中啤酒花数和频道数量取决于音频文件的长度和数量，而功能的数量是音频数据中请求的功能数量。
numFiles = numel(specs)
numfiles = 12
[numHops1，numFeaturesFile1，numchanelsfile1] = size（specs {1}）
numhops1 = 1053
NumFeaturesFile1 = 620
NumChanelsFile1 = 1
[numHops2，numFeaturesFile2，numchanelsfile2] = size（specs {2}）
numhops2 = 443
numFeaturesFile2 = 620
numChanelsFile2 = 1
算法
这AudioFeatUreExtractorcreates a feature extraction pipeline based on your selected features. To reduce computations,AudioFeatUreExtractor重用中介表示。一些中间表示形式可以作为功能输出：
例如,要创建一个对象,提取centroid of the Bark spectrum, the flux of the Bark spectrum, the pitch, the harmonic ratio, and the delta-delta of the MFCC, specify theAudioFeatUreExtractoras:
AFE= AudioFeatUreExtractor（。。。"SpectralDescriptorInput","barkSpectrum",。。。"spectralCentroid",true,。。。"spectralFlux",true,。。。"pitch",true,。。。“谐音”,true,。。。“ mfccdeltadelta”,true)
AFE= audioFeatureExtractor with properties: Properties Window: [1024×1 double] OverlapLength: 512 SampleRate: 44100 FFTLength: [] SpectralDescriptorInput: 'barkSpectrum' Enabled Features mfccDeltaDelta, spectralCentroid, spectralFlux, pitch, harmonicRatio Disabled Features linearSpectrum, melSpectrum, barkSpectrum, erbSpectrum, mfcc, mfccDelta gtcc, gtccDelta, gtccDeltaDelta, spectralCrest, spectralDecrease, spectralEntropy spectralFlatness, spectralKurtosis, spectralRolloffPoint, spectralSkewness, spectralSlope, spectralSpread To extract a feature, set the corresponding property to true. For example, obj.mfcc = true, adds mfcc to the list of enabled features.
Note
BecauseAudioFeatUreExtractorreuses intermediary representations, the features output fromAudioFeatUreExtractor通过相应的单个特征提取器，可能与功能输出的默认配置相对应。
兼容性考虑
Extended Capabilities
选择一个网站
Choose a web site to get translated content where available and see local events and offers. Based on your location, we recommend that you select:。
Select网站您还可以从以下列表中选择一个网站：
美洲
- AméricaLatina(Español)
- 加拿大（英语）
- 美国（英语）
