On 3/28/14 12:25 PM, Didier Dambrin wrote:
my opinion is: above 14bit, dithering is pointless (other than for marketing reasons),
14 bits??? i seriously disagree. i dunno about you, but i still listen to red-book CDs (which are 2-channel, uncompressed 16-bit fixed-point). they would sound like excrement if not well dithered when mastered to the 16-bit medium.
in fact, i think that in a very real manner, Stan Lipshitz and John Vanderkooy and maybe their grad student, Robert Wannamaker, did no less than *save* the red-book CD format in the late 80s, early 90s. and they did it without touching the actual format. same 44.1 kHz, same 2-channels, same 16-bit fixed-point PCM words. they did it with optimizing the quantization to 16 bits and they did that with (1) dithering the quantization and (2) noise-shaping the quantization.
the idea is to get the very best 16-bit words you can outa audio that has been recorded, synthesized, processed, and mixed to a much higher precision. i'm still sorta agnostic about float v. fixed except that i had shown that for the standard IEEE 32-bit floating format (which has 8 exponent bits), that you do better with 32-bit fixed as long as the headroom you need is less than 40 dB. if all you need is 12 dB headroom (and why would anyone need more than that?) you will have 28 dB better S/N ratio with 32-bit fixed-point.
and all of the "demonstrations" will always make you hear 10bit worth of audio in a 16bit file & tell you to crank the volume to death
to *hear* a difference non-subtly, you may have to go down to as few as 7 bits. in 2008 i presented a side-by-side comparison between floating-point and fixed-point quantization ( http://www.aes.org/events/125/tutorials/session.cfm?code=T19 ) trying to compare apples-to-apples. and i wanted people to readily hear differences. in order to do that i had to go down to 7 bits (the floats had 3 exponent bits, 1 sign bit, 3 additional mantissa bits and a hidden leading "1").
-- r b-j r...@audioimagination.com "Imagination is more important than knowledge." -- dupswapdrop -- the music-dsp mailing list and website: subscription info, FAQ, source code archive, list archive, book reviews, dsp links http://music.columbia.edu/cmc/music-dsp http://music.columbia.edu/mailman/listinfo/music-dsp
