SWIFT iOS 13中基频的对数（基数e）

Question

iOS 13的SFVoiceAnalytics将音调值保存为标准化音调的对数（以e为底）。如何解压缩这些数据以将其用作基频/赫兹？ exp2（）是正确的解决方案吗？谢谢！

var expArray = [Double]()
for (_, elem) in track!.pitchArray!.enumerated() {
    let e = exp2(elem)
    expArray.append(e)
}

这些是音高pitchArray的值：

([-0.9454506039619446, -0.893652081489563, -0.6501625776290894, -0.36013153195381165, -0.22758783400058746, -0.08258935809135437, -0.045184697955846786, -0.060198232531547546, -0.45403632521629333, -0.37330225110054016, -0.46266263723373413, -0.24363973736763, -0.14484688639640808, -0.11881064623594284, -0.17437025904655457, -0.23510295152664185, -0.17646336555480957, 0.0089696254581213, 0.15164943039417267, 0.13102009892463684, 0.09598015993833542, 0.05285550653934479, 0.07520392537117004, 0.014422144740819931, 0.045051347464323044, 0.014238571748137474, -0.054729610681533813, -0.0005990013014525175, -0.11587730795145035, -0.020161233842372894, -0.09440755844116211, -0.16037273406982422, -0.08368249237537384, -0.05901040509343147, 0.017956847324967384, -0.054717157036066055, -0.2358042597770691, -0.193386510014534, -0.2547127306461334, -0.187450110912323, -0.09919071197509766, -0.13081444799900055, -0.0924646258354187, -0.13903743028640747, -0.0783318281173706, -0.020551644265651703, -0.03663574159145355, 0.060199059545993805, -0.10958904027938843, -0.02268839254975319, -0.14984825253486633, 0.044030528515577316, -0.00406426377594471, 0.02257164940237999, -0.02609996870160103, -0.029283499345183372, 0.032108720391988754, 0.15555286407470703, 0.11224140226840973, 0.13462059199810028, 0.2033012956380844, 0.03364952653646469, 0.09982913732528687, 0.010672260075807571, 0.07193995267152786, 0.004444553051143885, -0.023822244256734848, 0.02343841828405857, 0.04362811893224716, -0.018942059949040413, 0.09457628428936005, 0.21903130412101746, 0.15494093298912048,...

这些是exp2（）之后的值

[0.5192673410228762, 0.53824985039432, 0.6372085024438401, 0.7790935456824871, 0.8540616778734259, 0.9443611794089626, 0.9691657336163281, 0.9591323213459376, 0.729997624689151, 0.7720133758730586, 0.7256457705734723, 0.8446117733445299, 0.9044753646754291, 0.9209465635349718, 0.8861542438262539, 0.8496243673043126, 0.8848695160761638, 1.0062366379403476, 1.110838766108783, 1.0950677266375144, 1.0687912930035801, 1.0373160387312566, 1.053509939372661, 1.0100468025770375, 1.031719898952058, 1.0099182892647942, 0.9627748690683745, 0.999584890118704, 0.92282096937803, 0.9861224904851085, 0.9366568058341782, 0.8947938625046091, 0.9436459051772645, 0.9599223378033335, 1.0125245211196217, 0.9627831799783695, 0.8492114569100799, 0.8745504341740961, 0.8381540112318564, 0.8781564467334525,...

Answer 1

否，exp2为2 to the power of the argument。您想要普通的exp并提高e to the power。