I know there's a parallel discussion about human hearing and what audio cards can get there. But I'm just trying to get one simple fact clear, that is the bit depth of audio in Pd :)
Leaving the human hearing or audio cards aside, some DAW (like Pro Tools or Ardour) do operate on audio files that are actual 32 bit resolution. I guess the idea is to keep quantization error as low as possible when mixing, normalizing, processing, filtering, mastering and everything. Then you can convert it to, say, 24 bit high quality audio afterwards for distribution - I guess this is the standard for highest digital audio these days, meaning that it's pointless to have a final audio that's higher than that, but then, 32 bit dac seem to be showing up already as chuck pointed out, but I digress. Moreover, you can also convert it to 16 bit CD quality afterwards, or even just make some MP3 or whatever...
Not to get into the discussion if dealing with 32 bits internally on a DAW is really important or worth the hassle (and not even getting into the deal with new 32 bit dac), the fact is that 32 bit audio exists out there for some time now. They do have this 32 bits option, or even more maybe... (not sure if they're pushing it to 64 yet, but it doesn't matter).
So, I always knew Pd was "32 bit", and knowing the above, I was misled to think Pd was just like Pro Tools or Ardour, that it could process audio in 32 bit. But I was thinking about it these days and it hit me that you just can't say Pd processes audio like Ardour and Pro Tools do on 32 bit precision.
Bottom line, you can't!
So this made me wonder what the heck that precision would be...
Chuck made me think it was a bit more than 24 bits, now it seems Miller says it's more likely to be 20 bits :)
cheers
2015-04-23 12:25 GMT-03:00 Miller Puckette msp@ucsd.edu:
I get 1 000 000 = 2^19.9 so a 20 bit dynamic range.
I don't think A/D/A hardware ever gets better than about 110 dB dtnamic range though.
cheers Miller
On Thu, Apr 23, 2015 at 05:20:51PM +0200, Cyrille Henry wrote:
Le 23/04/2015 16:41, Alexandre Torres Porres a écrit :
Yep, nice indeed, I guess I learned - in short and in layman's
undetailed terms - that audio output is ~24bits (a bit higher, but much higher for smaller numbers).
Moreover, digital audio cards won't likely have more than 24 bit
precision for many years to come, so it's just way more than enough.
The human ear is usually consider to be sensible from 0dB to 120dB, so a
range of 10^(12/2) between the smallest and biggest amplitude.
i.e from 1 to 1 000 000, or from 1 to 2^13.8 so, the human ear sensitivity can be considered to be about 14 bits. 16 bits diffusion should be enough. 24 bits diffusion is already overkill.
cheers c
thanks
2015-04-23 6:43 GMT-03:00 Julian Brooks <jbeezez@gmail.com <mailto:
jbeezez@gmail.com>>:
Nice. Thanks Chuck, I learnt something.
On 22 April 2015 at 23:45, Charles Z Henry <czhenry@gmail.com
mailto:czhenry@gmail.com> wrote:
On Wed, Apr 22, 2015 at 5:11 PM, Alexandre Torres Porres <porres@gmail.com <mailto:porres@gmail.com>> wrote: > So I start with this idea that the audio (values from -1 to
- can't be in
> full 32 bit float resolution, it's less. I don't see why thatis "wrong".
> And then, from it, my first question here was: "what is theaudio resolution
> then?". I'm still clueless here about this answer. > > Moreover, is it more or less than what 24 bit audio cardshandle?
Let me try: 32-bit floating point numbers have 24 bits of precision.Always. The
remaining 8 bits are just for the sign and exponent. When the amplitude of the signals decrease, you don't lose any precisionin
floating-point. The value of the least significant bit (LSB)gets
proportionally smaller. However, the output of a 24-bit soundcard always has a fixed quantization. The LSB is always the same size. Smallernumbers have
less precision. The mismatch occurs when converting from the 32-bit floats tothe
24-bit fixed point numbers. Now, the smaller numbers aren't as precise anymore. They get rounded to the nearest number in the24-bit
fixed point system. So, yes, the resolution (of small numbers) in floating point(internal
to Pd) is finer than the resolution of those numbers when output (driver/DAC). Also, the 24-bit fixed point format is for values between -1and 1.
That means that numbers between 0 and 1 have just 23 bits. In32-bit
math, the numbers between 0.5 and 1 still have 24 bits ofprecision
(the sign is held elsewhere). That means that Pd's internal resolution is finer than the soundcard resolution for allnumbers
between -1 and 1. Chuck _______________________________________________ Pd-list@lists.iem.at <mailto:Pd-list@lists.iem.at> mailing list UNSUBSCRIBE and account-management ->http://lists.puredata.info/listinfo/pd-list
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