Hi all, When running stat -freq, one gest a series of power spectra. The documentation states:
"The -freq option calculates the input's power spectrum (4096 point DFT) instead of the statistics listed above. This should only be used with a single channel audio file." The implication is that it is not guaranteed that the last power spectrum consists of a result based on 4096 points. To illustrate this, make a 30 second recording of a 125 Hz signal with an 48kHz sample rate. The three resulting spectra look like this: - first https://i.imgur.com/Erk1ouN.png - second https://i.imgur.com/78tBJpZ.png - third and last https://i.imgur.com/oWsF7H4.png It is clear that the last one is proper on the outline but has many intermediate points which are not desirable. This is of course understandable (and correct?). However, should this be noted in the documentation as a warning to prevent wrong assumptions? I can reproduce this almost always. With a WAV file of 487 MB the first and one but last power spectra look like https://i.imgur.com/ePpwM1d.png and https://i.imgur.com/NPkCSqA.png respectively but the last one is also malformed, see https://i.imgur.com/qjrxCbr.png When using averages over multiple power spectra, is it wise to ignore the last one? Is there a way to calculate when the DFT fits exactly and the last one doesn't have to be ignored? Can automatic notification this be part of sox? Regards, Pander ------------------------------------------------------------------------------ Dive into the World of Parallel Programming The Go Parallel Website, sponsored by Intel and developed in partnership with Slashdot Media, is your hub for all things parallel software development, from weekly thought leadership blogs to news, videos, case studies, tutorials and more. Take a look and join the conversation now. http://goparallel.sourceforge.net/ _______________________________________________ SoX-devel mailing list SoX-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/sox-devel
