Comment by geraldmcboing | Hacker News Reader

Comment by geraldmcboing | Hacker News Reader

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Dude I've been doing sound design on films using these techniques for years. There is zero 'woo' involved, it is ALL practical evidence based use. I've been using 32bit float multitrack field recorder by Sound Devices MixPre10-II professionally for many years now. The recorder has three preamps per mic input, each gain staged to provide optimum signal to the 32bit float AD. Read this to clarify your thinking: https://www.sounddevices.com/32-bit-float-files-explained/

Surely you understand a recording made at 48kHz has a max freq response of 24kHz and played at half speed that max freq is 12kHz and at quarter speed only 6kHz. You can very clearly hear the filter cut off due to Nyquist. Record at 192kHz with mics capable of 100kHz capture and when played at quarter speed, the sound is full spectrum because there is no truncated frequency response. And when I load a 192kHz recording to izotope RX I can literallu see the harmonics going up to 96kHz. (not with every sound of course)

I repeat, i am not talking about 'normal' listening. I am talking about an industruy you have no knowledge or lived experience with, so spare me the incorrect claims about what can & cant be heard.

> I am talking about an industruy you have no knowledge or lived experience with

I'm the original/lead developer of Ardour, a cross-platform DAW, and have been working with digital audio for more than 25 years.

There are no 32 bit ADCs - your SD MixPre's are giving you (at best) 22 bits packaged as a 32 bit float value. The preamps make absolutely zero difference to the AD conversion (though they might sound real nice).

> Surely you understand a recording made at 48kHz has a max freq response of 24kHz and played at half speed that max freq is 12kHz

This is a very naive version of what "played at half speed" might actually mean. If properly and correctly resampled, this is not true.

> And when I load a 192kHz recording to izotope RX I can literallu see the harmonics going up to 96kHz

Well, I'd certainly hope so! But the question is: what are the energy levels associated with the partials above Nyquist? If you recorded at 384kHz with sensitive enough equipment, you'd see partials above 96kHz - but at extremely low energies because ... well, that's just how physics works.

[EDITED to remove AD/DA confusion]

I do not use the DACs in the MixPre. Its a recording device. The field recordings & studio recordings are transferred as data and used in a 32bit float 192kHz Protools session. So the recorders DAC is completely irrelevant. The sounds are then used as source material, for processing and manipulation at 192k, 96k and 48k. There is no debate to be had. This is how film sound designers work & have worked for years now.

The half speed you call naive is again just showing your ignorance. Sound editors have been using this technique since the days of recording on a Nagra at 15ips and literally replaying at 7.5ips half speed, and at 3.75ips for quarter speed. There is nothing naive about it, it is a very well know technique. To be able to achieve the same result digitally with full spectrum has impacted every feature film you have experienced in recent years. Again I speak from decades of lived experience.

Running tape at half speed has almost nothing to do with digital resampling, which is what playing digital audio at half speed is generally all about.

My use of DAC was a thinko, I've edited at least post to correct it since in the current context we're always talking about ADC. Apologies for that.

Wrong again. As a sound designer I can choose to import a 192kHz file into a 48kHz PT session in two ways, one as resampled audio which means pitch & duration stay the same, OR I can choose to import it without SR conversion, in which case the audio plays at quarter speed & pitch is 2 octaves lower. We use both techniques ALL the time, every day. It's a common technique every sound designer uses.

You are arguing about techniques you have no experience with.

I wrote a DAW that does precisely what you describe. I've been doing it for 25 years.

cperciva moment right here

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