Hardware Misc Biquad Filters?

[Melodybun]

Hello,

A few weeks ago, I got in touch with the lead dev of Luma3DS about pitch shifting my 3DS -- I was told that it may be possible to do so by applying a biquad filter or two. Please see the below screenshot:

I am awaiting clarification on how to actually do so, but I wanted to ask about it here in the interim. What exactly is a biquad filter, how do I make heads or tails of that biquad filter calculator that I was linked by the dev, and how would I actually go about fixing my audio with such a filter? (Also, on my main PC, I have an audio driver that lets me easily pitch shift -- on my backup, I have Peace and EqAPO.)

It seems that biquad filters are sort of... arcane knowledge, or something. On this site alone, there are apparently only four other mentions of one -- and one of those is mine!

 

[PoorPocketsMcNewHold]

Ain't as knowledgeable, but I'm still going to assume an answer.

A biquad filter is just a filter, using biquadratic equations. Making it that way, make it easier to port it to different DSP system as it is just math based entirely, and should behave the same in others,
The advantage of making it programmatically is well, to make it easier to process too but in the case of the 3DS, i don't really think it changes a whole lot.

Fixed point DSP usually prefers the non transposed forms and has an accumulator with a large number of bits, and is rounded when stored in main memory. Floating point DSP usually prefers the transposed form, each multiplication and potentially each addition are rounded; the additions are higher precision result, when both operands have similar magnitude.

https://en.wikipedia.org/wiki/Digital_biquad_filter

I assume that term was just an unnecessary precision, that confused us (myself inclued trying to give a proper explanation).

 

[Melodybun]

Ain't as knowledgeable, but I'm still going to assume an answer.

A biquad filter is just a filter, using biquadratic equations. Making it that way, make it easier to port it to different DSP system as it is just math based entirely, and should behave the same in others,
The advantage of making it programmatically is well, to make it easier to process too but in the case of the 3DS, i don't really think it changes a whole lot.

https://en.wikipedia.org/wiki/Digital_biquad_filter

I assume that term was just an unnecessary precision, that confused us (myself inclued trying to give a proper explanation).

Hello,

Thank you for your patience -- also, that's good to know, tysm! From my perspective as a layperson, I'm guessing TuxSH was just suggesting that I program a similar filter. However, I am not certain where it would actually "go," roughly. Please see the below screenshot from my most recent thread on Luma3DS' Github page:

I cannot speak to the veracity of that statement, though. Thanks again!