But the key here is *bits*. If you're listening at normal levels, those
parts in music that "don't use all 16bits" (which is obvious, you can find
parts of all levels in a song) will be quieter, & thus the noise will be
less audible.
Put a sine wave in the lowest 1 or 2 bits of a 16bit piece of audio, it
should be horrible noise, right? If you crank up your volume until you hear
that sinewave, obviously it will. But at normal listening level, are you
really gonna hear that sinewave or worse, its horrible noise? My bet would
be *maybe*, in an anechoic room, after a couple of hours of getting used to
silence.
he cost is virtual nothing
I will certainly not disagree with that, it doesn't hurt & costs (almost)
nothing. But it's still snake oil.
Our biggest difference is that you are looking at this from the
end-listener point of view.
Yes, because that's the only thing 16bit audio applies to, the end listener.
Ok, apparently some still need to publish 16bit audio files for pro's
because not every tool out there (I guess) supports 24 (& I would still
advise against storing in integer format at all) or 32bit formats - this is
most likely not gonna last very long.
Talking about this, in a world where the end listener almost always listens
in lossy encoded formats, the 16bit quantization problem isn't even a shrimp
in the whole universe.
-----Message d'origine-----
From: Nigel Redmon
Sent: Thursday, February 05, 2015 7:13 PM
To: A discussion list for music-related DSP
Subject: Re: [music-dsp] Dither video and articles
Music is not typically full scale. My level was arbitrary—where the mixer
knob happened to be sitting—but the note is relatively loud in a musical
setting.
You don’t get to use all 16 bits, all the time in music. So, to complain
that it might as well be 13-bit…well, if we had 13-bit converters and sample
size, we’d be having this discussion about 10-bit. The bass note is LOUD,
compared to similar bits in actual music, as I’m playing from iTunes right
now.
OK, I’m not trying to convince you—it was obvious that we’d have to agree to
disagree on this. And, as you know, I’m not overstating the importance of
dithering 16-bit audio, as many others do. I’m simply saying that it’s worth
it—the cost is virtual nothing (it’s not even don’t in real time, but just
for the final bounce to disk), doing it doesn’t harm the music in any way
(if you can hear the distortion, I don’t think you’ll hear 16-bit flat
dither).
Our biggest difference is that you are looking at this from the end-listener
point of view. But why would I be giving advice to the listener? They aren’t
the ones making the choice to dither or not. The advice is for people in the
position of dithering. And these people do hear it. If my advice were “Don’t
bother—you can’t hear it anyway”, these people would think I’m an idiot—of
course they can hear it. Their business is to look for junk and grunge and
get rid of it. I can envision Bob Katz, Bob Olson, and Bruce Swedien
knocking at my door, wanting to beat me with a microphone stand and pop
screens for telling them that they can’t hear this stuff. (Just kidding,
they seem like really nice guys.)
The funny thing is that I’m arguing in favor of 16-bit dither with you, and
having a similar exchange with a mastering engineer, who is sending me
examples of why we really must dither at 24-bit ...
On Feb 5, 2015, at 9:49 AM, Didier Dambrin <di...@skynet.be> wrote:
If you mean that the peak loudness of the synth isn’t hitting full scale
Yeah I mean that, since, to compensate, you crank your volume up, making
it 13bit worth (from 14bit, after your extra -6dB gain)
I mean it's always the same debate with dithering, one could demonstrate
exactly the same with 8bit worth of audio in a 16bit file. To me a 16bit
file is 16bit worth of audio, for the whole project, thus with the loudest
parts of the project designed to be listened to. If the entire project
peaks at -18dB, then it's not designed to be listened to at the same level
as other 16bit files, and thus it's not 16bit worth of audio. One could go
further & store 1 bit worth of audio in a 16bit file and point out how
degraded it is.
Quantization & loss is everywhere in a computer (obviously) and magnifying
it doesn't make a point, because you always can bring the imperceptible
back to perception. To me it's all about what's perceptible when the
project is used as intended, otherwise, even 64bit float audio should be
marked as "lossy".
I could have had a louder sound with a similar tail that would have
produced the same distortion.
yeah, except that louder sound would have killed your ears, so you would
have cranked your listening level down, and not heard the noise anymore
-----Message d'origine----- From: Nigel Redmon
Sent: Thursday, February 05, 2015 6:22 PM
To: A discussion list for music-related DSP
Subject: Re: [music-dsp] Dither video and articles
Oh, sorry about the 6 dB. I made the 16- and 32-bit versions, then noticed
I had the gain slider on the DP mixer pushed up. I pulled it back to 0 dB
and made new bounces, plus the residual and dithered version subsequently,
but must have grabbed the wrong 32-bit version for upload.
I have no idea what you’re implying about "IMHO this is 13bit worth of
audio inside a 16bit file”. I took care to have no gain after the
truncation (except the accidental 6 dB on the 32-bit file). If you mean
that the peak loudness of the synth isn’t hitting full scale, then, A)
welcome to music, and B) it’s immaterial—I could have had a louder sound
with a similar tail that would have produced the same distortion.
I’m not surprised you couldn’t hear it, as I said it required fairly high
listening levels and I don’t know what your equipment is. It can be heard
on a professional monitoring system. I’m monitoring off my TASCAM DM-3200,
and it does not have a loud headphone amp—I can’t hear it there. But it’s
right on the edge—if I boost it +6 dB I have no problem hearing it. But my
monitoring speakers get louder than the headphones, so I can hear it
there. And I know engineers who routinely monitor much louder than my gear
can get.
On Feb 5, 2015, at 4:55 AM, Didier Dambrin <di...@skynet.be> wrote:
I couldn't hear any difference (through headphones), even after an insane
boost, and even though your 16bit truncated wav was 6dB(?) lower than the
32bit wav
But even if I could hear it, IMHO this is 13bit worth of audio inside a
16bit file.
-----Message d'origine----- From: Nigel Redmon
Sent: Thursday, February 05, 2015 9:13 AM
To: A discussion list for music-related DSP
Subject: Re: [music-dsp] Dither video and articles
OK, here’s my new piece, I call it Diva bass—to satisfy your request for
me to make something with truncation distortion apparent. (If it bother
you that my piece is one note, imagine that this is just the last note of
a longer piece.)
I spent maybe 30 seconds getting the sound—opened Diva (default
“minimoog” modules), turn the mixer knobs down except for VCO 1, set
range to 32’, waveform to triangle, max release on the VCA envelope.
In 32-bit float glory:
http://earlevel.com/temp/music-dsp/Diva%20bass%2032-bit%20float.wav
Truncated to 16-bit, no dither (Quan Jr plug-in, Digital Performer),
saved to 16-bit wave file:
http://earlevel.com/temp/music-dsp/Diva%20bass%2016-bit%20truncated.wav
You’ll have to turn your sound system up, not insanely loud, but loud. (I
said that this would be the case before.) I can hear it, and I know
engineers who monitor much louder, routinely, than I’m monitoring to hear
this. My Equator Q10s are not terribly high powered, and I’m not adding
any other gain ahead of them in order to boost the quiet part.
If you want to hear the residual easily (32-bit version inverted, summed
with 16-bit truncated, the result with +40 dB gain via Trim plug-in):
http://earlevel.com/temp/music-dsp/Diva%20bass%2016-bit%20truncated%20residual%20+40dB.wav
I don’t expect the 16-bit truncated version to bother you, but it does
bother some audio engineers. Here's 16-bit dithered version, for
completeness, so that you can decide if the added noise floor bothers
you:
http://earlevel.com/temp/music-dsp/Diva%20bass%2016-bit%20dithered.wav
On Feb 4, 2015, at 1:10 PM, Didier Dambrin <di...@skynet.be> wrote:
Yes, I disagree with the "always". "Not always needed" means "it's
sometimes needed", my point is that it's never needed, until proven
otherwise. Your video proves that sometimes it's not needed, but not
that sometimes it's needed.
-----Message d'origine----- From: Nigel Redmon
Sent: Wednesday, February 04, 2015 6:51 PM
To: A discussion list for music-related DSP
Subject: Re: [music-dsp] Dither video and articles
I totally understood the point of your video, that dithering to 16bit
isn't always needed - but that's what I disagree with.
Sorry, Didier, I’m confused now. I took from your previous message that
you feel 16-bit doesn’t need to be dithered ("dithering to 16bit will
never make any audible difference”). Here you say that you disagree with
"dithering to 16bit isn't always needed”. In fact, you are saying that
it’s never needed—you disagree because “isn’t always needed” implies
that it is sometimes needed—correct?
On Feb 4, 2015, at 5:06 AM, Didier Dambrin <di...@skynet.be> wrote:
Then, it’s no-win situation, because I could EASILY manufacture a bit
of music that had significant truncation distortion at 16-bit.
Please do, I would really like to hear it.
I have never heard truncation noise at 16bit, other than by playing
with levels in a such a way that the peaking parts of the rest of the
sound would destroy your ears or be very unpleasant at best. (you say
12dB, it's already a lot)
I totally understood the point of your video, that dithering to 16bit
isn't always needed - but that's what I disagree with.
-----Message d'origine----- From: Nigel Redmon
Sent: Wednesday, February 04, 2015 10:59 AM
To: A discussion list for music-related DSP
Subject: Re: [music-dsp] Dither video and articles
Hi Didier—You seem to find contradictions in my choices because you are
making the wrong assumptions about what I’m showing and saying.
First, I’m not steadfast that 16-bit dither is always needed—and in
fact the point of the video was that I was showing you (the viewers)
how you can judge it objectively for yourself (and decide whether you
want to dither). This is a much better way that the usual that I hear
from people, who often listen to the dithered and non-dithered results,
and talk about the "soundstage collapsing" without dither, “brittle”
versus “transparent" , etc.
But if I’m to give you a rule of thumb, a practical bit of advice that
you can apply without concern that you might be doing something wrong
in a given circumstance, that advice is “always dither 16-bit
reductions”. First, I suspect that it’s below the existing noise floor
of most music (even so, things like slow fades of the master fader
might override that, for that point in time). Still, it’s not hard to
manufacture something musical that subject to bad truncation
distortion—a naked, low frequency, low-haromic-content sound (a
synthetic bass or floor tom perhaps). Anyway, at worst case, you’ve
added white noise that you are unlikely to hear—and if you do, so what?
If broadband noise below -90 dB were a deal-breaker in recorded music,
there wouldn’t be any recorded music. Yeah, truncation distortion at
16-bits is an edge case, but the cost to remove it is almost nothing.
You say that we can’t perceive quantization above 14-bit, but of course
we can. If you can perceive it at 14-bit in a given circumstance, and
it’s an extended low-level passage, you can easily raise the volume
control another 12 dB and be in the same situation at 16-bit. Granted,
it’s most likely that the recording engineer hears it and not the
end-listener, but who is this video aimed at if not the recording
engineer? He’s the one making the choice of whether to dither.
Specifically:
..then why not use a piece of audio that does prove the point,
instead? I know why, it's because you can’t...
First, I would have to use my own music (because I don’t own 32-bit
float versions of other peoples’ music, even if I thought it was fair
use to of copyrighted material). Then, it’s no-win situation, because I
could EASILY manufacture a bit of music that had significant truncation
distortion at 16-bit. I only need to fire up one of my soft synths, and
ring out some dull bell tones and bass sounds. Then people would accuse
me of fitting the data to the theory, and this isn’t typical music made
in a typical high-end study by a professional engineer. And my video
would be 20 minutes long because I’m not looking at a 40-second bit of
music any more. Instead, I clearly explained my choice, and it proved
to be a pretty good one, and probably fairly typical at 16-bit, wouldn’t
you agree? As I mentioned at the end of the video, the plan is to
further examine some high-resolution music that a Grammy award-winning
engineer and producer friend of mine has said he will provide.
...and dithering to 16bit will never make any audible difference.
If you mean “never make any audible difference” in the sense that it
won’t matter one bit to sales or musical enjoyment, I agree. I imagine
photographers make fixes and color tweaks that will never be noticed in
the magazine or webpage that the photo will end up in either. But I
guarantee you, there are lots of audio engineers that will not let that
practically (using the word in the original “practical" sense–don’t
read as “almost") un-hearable zipper in the fade go. If they know it’s
there, and in some cases they CAN actually hear it, with the volume
cranked, you can tell them all day and all night that they are wasting
there time dithering, because listeners will never hear it, but they
will want to get rid of it. And the cost of that rash action to get rid
of it? Basically nothing. Hence my advice: Dither and don’t worry about
it—or listen to the residual up close and see if there’s nothing to
worry about, if you prefer.
On Feb 3, 2015, at 10:24 PM, Didier Dambrin <di...@skynet.be> wrote:
Sorry, but if I sum up this video, it goes like this:
you need dithering to 16bit and I'm going to prove it, then the video
actually proves that you don't need it starting at 14bit, but adds
"it's only because of the nature of the sound I used for demo".
..then why not use a piece of audio that does prove the point,
instead?
I know why, it's because you can't, and dithering to 16bit will never
make any audible difference.
It's ok to tell the world to dither to 16bit, because it's nothing
harmful either (it only mislays people from the actual problems that
matter in mixing). But if there is such a piece of audio that makes
dithering to 16bit any audible, without an abnormally massive boost to
hear it, I'd like to hear it.
Andrew says he agrees, but then adds that it's important when you
post-edit the sound. Yes it is, totally, but if you're gonna post-edit
the sound, you will rather keep it 32 or 24bit anyway - the argument
about dithering to 16bit is for the final mix.
To me, until proven otherwise, for normal-to-(not abnormally)-high
dynamic ranges, we can't perceive quantization above 14bit for audio,
and 10bits for images on a screen (debatable here because monitors
aren't linear but that's another story). Yet people seem to care less
about images, and there's gradient banding all over the place.
-----Message d'origine----- From: Andrew Simper
Sent: Wednesday, February 04, 2015 6:06 AM
To: A discussion list for music-related DSP
Subject: Re: [music-dsp] Dither video and articles
Hi Nigel,
Isn't the rule of thumb in IT estimates something like: "Double the
time you estimated, then move it up to the next time unit"? So 2 weeks
actually means 4 months, but since we're in Music IT I think we should
be allowed 5 times instead of 2, so from my point of view you've
actually delivered on time ;)
Thanks very much for doing the video! I agree with your recommended
workflows of 16 bit = always dither, and 24 bit = don't dither. I
would probably go further and say just use triangular dither, since at
some time in the future you may want to pitch the sound down (ie for a
sample library of drums with a tom you want to tune downwards, or
remixing a song) then any noise shaped dither will cause an issue
since the noise will become audible.
All the best,
Andrew
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