New answers tagged stft
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Is STFT more computationally demanding that the CWT?
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If yes then how can this be done ?
Yes, it can be done. But doing it directly in the frequency domain is awkward, cumbersome and slow.
The most efficient way is to generate it directly in the time domain using a rotating phasor. If you need it in the STFT domain, just generate a properly aligned frame of data in the time domain, window and FFT it. That's ...
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If this is about using the STFT, then it's about frames of audio (or whatever signal class) and, if it's about frames, it's about windows. Usually the windows we want are complementary, they add to 1. An example would be a Hann window.
So now imagine your sinusoid of an arbitrary frequency (mid bin or between bins or something else) being multiplied by a ...
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A sinusoid with a frequency that is between bins in the FFT frequency domain is circularly discontinuous in the time domain. So you can't use the same IFFT results back-to-back without the noise from this discontinuity between each IFFT window, as the end of one window will have a value too far from the beginning of the next window (unless your frequency is ...
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However, since I have taken the modulus, it must be impossible to go from spec back to audio correct?
You need to resort to some approximations like the Griffin-Lim algorithm or various vocoders (WaveNet,WaveGlow,etc.).
So does that mean that librosa.istft does NOT convert a spectrogram to a wav file?
It's a bit more complicated than that. An FFT ideally ...
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dB is a power ratio, so when we see units in dB we are seeing units on a relative scale. The reason that a 0 dB reference is so common is because this is simply normalizing the number scale to 1. $10Log(1) = 0$ dB
This is similar to using 100% (1) instead of absolute numbers.
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This is not generally true. As mentioned in the comments, it may be a preference to take the maximum of the signal as 0 dB. But a counter example is the power measurements in wireless systems. We define dBm as:
$P [dBm] = 10log(P / 1 (mW))$
We may have actual powers as high as 30 dBm. The voice ratings are other counter examples. There is no single ...
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