Re: Stereo > Mono Downmixing on iOS
Re: Stereo > Mono Downmixing on iOS
- Subject: Re: Stereo > Mono Downmixing on iOS
- From: Brian Willoughby <email@hidden>
- Date: Mon, 04 Apr 2011 01:25:29 -0700
On Apr 3, 2011, at 23:49, tahome izwah wrote:
2011/4/3 Richard Dobson <email@hidden>:
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.
Care to share any pointers?
Sample Rate Conversion is one good example. See:
http://src.infinitewave.ca/
Apple's AudioConverter SRC in CoreAudio comes in very close to the
top of the list in quality. That site does not strictly have a
"list" but you can browse the various SRC implementations and find
the best performers interactively. That said, the iZotope 64-bit SRC
is just about the only one which outdoes Apple's (presumably 32-bit)
implementation. I'm fairly certain that the 64-bit implementation is
the bulk of the reason for the increased performance. Note the noise
floor of 24-bit and 32-bit SRC algorithms, and compare the nearly-
silent 64-bit implementation.
Apart from SRC, many filtering and other frequency-domain DSP
benefits from 64-bit implementation. Granted, 32-bit is often enough
to suffice, given that floating point adapts to small signals quite
well. I assume that there are filters which benefit from 64-bit math
just as much as SRC.
Brian Willoughby
Sound Consulting
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