Audio and signal processing - unsorted stuff: Difference between revisions
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Analysis of the spectral envelope of a digital signal, with | Analysis of the spectral envelope of a digital signal, | ||
with some basic assumptions of mostly-voiced speech, | |||
and therefore useful for speech parameter estimation - and for that ''only''. | |||
e.g. seen in LPC vocoders, often for speech transmission. | e.g. seen in LPC vocoders, often for speech transmission. | ||
LPC was created to compress speech (into parameters rather than a squished waveform). | |||
That model is roughly to use the vowel/noise, three-filter | |||
LPC is still useful because that process of compression was required to find formants, | |||
and estimate pitch, which remain rather useful things in e.g. phonetics, speech recognition. | |||
Linear prediction | Linear Predictive coding, in the widest sense, is linear prediction applied to digital signals. | ||
Where linear prediction is estimation based on a linear function - conceptually a little more than interpolation/extrapolation, or linear regression, but not by much. | |||
Linear prediction itself is more often part of larger systems (e.g. as a smoother in a Kalman filter) | |||
Warped LPC (WLPC) | |||
Revision as of 15:57, 24 October 2023
Speech analysis and processing
Source-filter model
Vocoders
Voice coders analyses speech into parameeters, then synthesizes based on those parameters.
They were once made with the idea to parametrize speech for efficient transmission.
It was an important development in telecom, and also used in phonetics.
It was also potentially an instrument of sorts. A voder is the production part only, and sometimes is even a playable machine[1].
These days vocoders are mostly used to distort vocals and instruments in music.
See also:
- http://en.wikipedia.org/wiki/Vocoder
- http://en.wikipedia.org/wiki/Envelope_follower
- http://en.wikipedia.org/wiki/Phase_vocoder