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Is it easy to recreate audio from, say, an image file of the spectrogram results?
by arthurcolle 6y ago
Is it easy to recreate audio from, say, an image file of the spectrogram results?
- gbh444g 6y agoNo. But with enough effort and reasonable assumptions, you can restore most of the sound. It would be enough for speech, but not enough for high quality music.
- Zenst 6y agoYes. Demonstration of this being done: http://arss.sourceforge.net/examples.shtml http://arss.sourceforge.net/examples.shtml
- piannucci 6y agoTo add to what others have said-- The spectrogram image contains amplitude, but not phase information. (There are partial exceptions in special cases involving oversampling.) Conveniently, the human auditory system is primarily sensitive to the same information present in the spectrogram.
- high_byte 6y agoI wonder what phase sensitivity would sound (hear?) like
- JKCalhoun 6y agoI have been told we cannot distinguish phase. I have been told audio -> FFT —> audio (the kind of standard audio compression/decompression algorithms we use) lose that phase information and we can't tell. I have been told the "phase information" is the imaginary part of the complex numbers that are involved in an FFT.
- deleted 6y ago[deleted]
- bsmith0 6y agoYes, I built a really bad version of it a while ago: https://braeden.dev/waterfall/ https://braeden.dev/waterfall/ Click waterfall, and then click play when you have the audio on your computer playing outloud. If you play the audio outloud, your mic should be able to pick up a barely recognizable version of the picture (try the heart first to calibrate the "row delay"). https://github.com/braeden/waterfall https://github.com/braeden/waterfall Take a look at the example pictures on github ^, poor, but functional fully web version.
- arthurcolle 6y agoAmazing work! Knocked it out of the part. Have you checked out the other guy's example in the same subtree from the comment you posted on? Curious your take on that work. Keep it up!
- findthewords 6y agoThe bog-standard spectrogram you see in most programs is very lossy and ”smeary”. Clearer, sharper algorithms exist.
- fortran77 6y agohttps://www.mathworks.com/help/matlab/ref/ifft.html https://www.mathworks.com/help/matlab/ref/ifft.html