Re: Stereo > Mono Downmixing on iOS
Re: Stereo > Mono Downmixing on iOS
- Subject: Re: Stereo > Mono Downmixing on iOS
- From: Richard Dobson <email@hidden>
- Date: Sun, 03 Apr 2011 17:35:39 +0100
On 03/04/2011 17:10, 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!
Summing is not the only thing music software has to do - for signal
processing tasks, it was found a while ago that 32bit floats were not
quite sufficient for many tasks, especially considering high-resolution
formats. The VST standard for example introduced a 64bit processing
option for plugins relatively recently; similarly Csound is now
available in double precision as well as the traditional single
precision floats; and several users have reported that can hear a clear
difference. For "raw" summing, 32bit floats is sufficient until you get
to relatively huge numbers of elements (e.g for streaming pvoc phase
increments over long time periods it is not enough - rounding errors
~do~ aaccumulate), but 64bit double precision is routinely used for most
dsp processing on consumer workstations, and on a modern 64bit platform
may even be faster than floats. Down-conversion from doubles to singles
is not entirely overhead-free - it is quite nice not to have to do it
umpteen times. And now that "32 bit processing" is no longer the
cutting-edge technology it was, and has ceased to impress the otherwise
impressionable, one can forgive companies (or their marketing people)
for wanting to raise the bar one way or another!
Richard Dobson
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