Re: Stereo > Mono Downmixing on iOS
Re: Stereo > Mono Downmixing on iOS
- Subject: Re: Stereo > Mono Downmixing on iOS
- From: James Chandler Jr <email@hidden>
- Date: Mon, 04 Apr 2011 02:11:33 -0400
There are situations where a double float or 64 bit fixed point actually can make a real-world DSP improvement, though stereo-to-mono mixing may not be a shining example.
The smart people may nowadays all be in SIMD instructions for DSP, though I'm a relic who still mostly uses the FPU.
The code I write is "fast enough on modern machines" using doubles. Doubles are almost always numerically adequate. It seems easiest to always use doubles for all intermediate calculations and saved states. So if there may be unforseen edge cases where a 32 bit float would degrade the results in a tortured iterative calculation, I do not have to worry about it. This saves time deliberating on what is the minimum numeric depth adequate for each individual program task. And avoids possibly making wrong guesses in some cases.
On wimpy handheld processors where the luxury of fast float math has been snatched away from a programmer's toolkit, then the objective of "fast enough code" might force one back to the stone age of tedious hand-tuned fixed-point processing?
James Chandler Jr.
On Apr 3, 2011, at 12:10 PM, Roman Thilenius wrote:
>
> On Apr 1, 2011, at 6:54 PM, Bob Lang wrote:
>
>>
>> On 1 Apr 2011, at 01:20, Richard Dobson wrote:
>>> This thread is becoming surreal.
>>
>> But useful and interesting, none the less. I dare say a lot of people who wind up here have come by a variety of routes, and not everyone will have a degree in acoustics, so an exposition of the basics can be illuminating.
>>
>> Bob
>
>
> for my part, given that we all accept the idea and calculation
> examples from richard, who said float 32 will always be enough
> for summing, i would find it most interesting to hear some
> excuses from all the developers and companies who are using
> 64-bit for their summing - which is true for probably every "daw"
> application except PT!
>
> with a smile,
>
> -110
>
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