Re^2: Audio input and processing

I have not tried audio input (yet), but found the combination of PDL and SoX quite powerful to synthesize and play sound, including spectral analysis. Here's a screenshot of one of my experiments (sine waves and playing with overtones).

I use PDL to create the raw audio data and SoX to pipe them to whatever sound system is available (means: also works on MS-Windows), the waveform and spectrum display happen in real-time.

I plan to write an article about stuff like this for quite some time now, but there are so many distractions...

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Re^3: Audio input and processing - recommendations by etj (Priest) on Jan 13, 2025 at 16:53 UTC
A little later: haj did write at least one article about PDL and sound-processing - I'm listening as I write this to the very nice bit of music he has at the end. For audio input, I'd note that a physical limitation of doing DFT on a finite, short window of discrete input is that it creates artifacts from cut-off. This is mitigated in various ways, and the easiest way in PDL-land is to use PDL::DSP::Windows. See jjatria's Advent article for more. More generally for real-time-ish stuff, PDL doesn't yet have a very fully-tested real-time capability. I still intend to experiment more fully, but one approach might be to set up a "flowing" transformation (so you pay the setup cost only once), then keep updating the input sample then reading the processed output. If anyone does have a go at that, I'd love to hear your findings!	[reply]

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Re^3: Audio input and processing - recommendations
by etj (Priest) on Jan 13, 2025 at 16:53 UTC

haj

one article about PDL and sound-processing

For audio input, I'd note that a physical limitation of doing DFT on a finite, short window of discrete input is that it creates artifacts from cut-off. This is mitigated in various ways, and the easiest way in PDL-land is to use PDL::DSP::Windows. See jjatria's Advent article for more.

More generally for real-time-ish stuff, PDL doesn't yet have a very fully-tested real-time capability. I still intend to experiment more fully, but one approach might be to set up a "flowing" transformation (so you pay the setup cost only once), then keep updating the input sample then reading the processed output. If anyone does have a go at that, I'd love to hear your findings!

[reply]