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Topic: 16 bits is more than enough (Read 8047 times)
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## 16 bits is more than enough

##### 2022-08-09 19:29:09
To get the picture on how huge  a 16 bits range is, let make an analogy with graph paper in millimeter. A single sheet in A4 format is 21 centimeters by 30 centimeters.

To draw on Y axis the value of a single 16 bits sample on a little millimeter square the size of a pen tip, one would need a sheet (a roll!) of more than 65 meters. That's the height of a building with more than 20 storeys. 7 rolls of 10 meters will do.

Now let pretend that your hand is shaking while blacken this tiny 1 mm square with the pen. You miss the square and draw the point in the adjacent ones, a +/- 2 mm error in both X & Y axis. You now have reduced the resolution to 14 bits and added (depending the abscissa scale you choose) some jitters.

Could you spot this 2 mm error on the audio signal if it was projected as a picture on the facade of a building big as the Taj Mahal?  Could you hear it ? I doubt it. As to listen to this sound you'll have to stand back at least 50 meters from the facade.

I know that something opposes this analogy:  Hearing works on a logarithmic scale. Even so, analog ICs, PCB, cables, as the paper sheet, work in a linear world. LSB will be kind of submerged in a full 2**16 amplitude.

With 24 bits it's the same story but we'll need 1700 rolls of 10 meters length graph paper to exactly place the sample. 1,700 * 10 m = 17 km or 60 times the height of the Eiffel Tower. Stand back 20 km away. Can you see if the 1 mm2 point is in its right place, not 1 or 2 mm to high ? Look again. And remember that visual perception is much more accurate than hearing

Ask yourself why scientific instruments costing the price of a car are stuck below 16 bits (more a format than a resolution) even for very low speed like 0.2 Hz while you can buy 24 bits audio players for peanuts.

## Re: 16 bits is more than enough

##### Reply #1 – 2022-08-10 00:51:18
16 bits is "more than enough" but not for the reasons you've described.  A 16-bit digital sample with noise shaping can capture up to 120 dB of signal-to-noise ratio.  There is no music produced or reproduced on the face of the earth that exceeds that, nor can modern electronic equipment be any quieter.

Instead, your analogy strikes me as similar to that made by people who argue higher resolution in images is analogous to higher sample rate in audio: higher pixel density allows finer visual detail, so more frequent samples should create higher audio fidelity.  Those people do not understand the way digital audio works.  A 44 KHz sample rate already can encode all the information needed to faithfully reproduce sinusoidal frequencies up to 20 KHz.  Again, there is no earthly music that requires anything more.

https://hydrogenaud.io/index.php?topic=106566.0
https://people.xiph.org/~xiphmont/demo/neil-young.html

## Re: 16 bits is more than enough

##### Reply #2 – 2022-08-10 04:39:04
Anything with at least 1 bit could be "enough", depends on sample rate.

## Re: 16 bits is more than enough

##### Reply #3 – 2022-08-10 09:10:25
What I would really like to know
What is up with all the oversized images on this forum lately?

## Re: 16 bits is more than enough

##### Reply #4 – 2022-08-10 09:22:29
What I would really like to know
What is up with all the oversized images on this forum lately?
Keeping up with time that demands increased bit depth even if there is no real need for it?

But seriously, maybe some forum admin could look into sizing defaults.

## Re: 16 bits is more than enough

##### Reply #5 – 2022-08-10 11:17:28
Our senses are impressively sensitive and scaleable.
16bit in PCM audio is enough but it's on the edge of enough. Undithered 14bit is distinguishable from 16bit.
Our vision is even more sensitive - 24bits for RGB are on the edge of enough, 16 bits are distinguishable from 24bits.
So, while the analogy is nice, it's not universal.

## Re: 16 bits is more than enough

##### Reply #6 – 2022-08-10 11:50:51
Our senses are impressively sensitive and scaleable.
16bit in PCM audio is enough but it's on the edge of enough. Undithered 14bit is distinguishable from 16bit.
Our vision is even more sensitive - 24bits for RGB are on the edge of enough, 16 bits are distinguishable from 24bits.
So, while the analogy is nice, it's not universal.
One usually have only 8 bits per primary color for distribution (lately increasing to 10 or 12). I would suggest that as the suitable analogy to audio. Having 3 color channels is more like the dual audio channels found in stereo.

You could say that the 3-channel matrixing to YCbCr is somewhat similar to mid-side stereo or low-order ambisonics (?), but even then the achromatic information found in the luma channel can usually be encoded with sufficient precision using 8-10 bits.

-k

## Re: 16 bits is more than enough

##### Reply #7 – 2022-08-10 12:02:41
What I would really like to know
What is up with all the oversized images on this forum lately?
Looks pretty normal to me with desktop Firefox and default font size? BTW, I reduced the attached image to 251 colors, my screen is 1920*1080 and set to 130dpi.

## Re: 16 bits is more than enough

##### Reply #8 – 2022-08-10 12:10:14

Our vision is even more sensitive - 24bits for RGB are on the edge of enough, 16 bits are distinguishable from 24bits.
So, while the analogy is nice, it's not universal.

Like Knutinh say a video file is more like a 3 * 8 bits channels audio file.
10 bits by primary color are more than enough  for the eyes.
Most of JPEG pic are 3 * 8 bits and they are perfect. Better than a Kodachrome.

## Re: 16 bits is more than enough

##### Reply #9 – 2022-08-10 12:19:05
What I would really like to know
What is up with all the oversized images on this forum lately?
Keeping up with time that demands increased bit depth even if there is no real need for it?

But seriously, maybe some forum admin could look into sizing defaults.

It was just to show the tiny millimeter square
Here 640 width. Looks not to scale on a 22 inch screen. But +150%

## Re: 16 bits is more than enough

##### Reply #10 – 2022-08-10 12:24:10
https://people.xiph.org/~xiphmont/demo/neil-young.html

"Misinformation and superstition only serve charlatans. So, let's cover some of the basics of why 24/192 distribution makes no sense  [...]. Why push back against 24/192? Because it's a solution to a problem that doesn't exist, a business model based on willful ignorance and scamming people."

## Re: 16 bits is more than enough

##### Reply #11 – 2022-08-10 14:31:12
What I would really like to know
What is up with all the oversized images on this forum lately?
Keeping up with time that demands increased bit depth even if there is no real need for it?

But seriously, maybe some forum admin could look into sizing defaults.
The OP is using external images (which I believe are always shown full size).
The OP can manually scale the image
Code: [Select]
`[img width=300]https://i.postimg.cc/Gpsq9f5Q/sheet.jpg[/img]`

The OP could also be manually thumb-nail the image
Code: [Select]
`[url=https://i.postimg.cc/3wxdc1Jg/a387a1b3.jpg][img width=200]https://i.postimg.cc/3wxdc1Jg/a387a1b3.jpg[/img][/url]`
korth

## Re: 16 bits is more than enough

##### Reply #12 – 2022-08-10 21:22:58
One usually have only 8 bits per primary color for distribution (lately increasing to 10 or 12).
It's worth noting that the move from 8 to 10 bits for video has almost nothing to do with picture quality. It mostly just improves compression efficiency. The main effect on PQ is a reduction in bandng artifacts, but reducing banding also improves compression. Most of the benefit comes from using 10 bits; using 12+ bits is approaching the same snake oil territory as 24/192 audio.

## Re: 16 bits is more than enough

##### Reply #13 – 2022-08-10 21:27:48
16bit is Red Book standard for CDs.

CDs only make about 22Hz per left and right channel.
"The lack of money is the root of all evil." - Mark Twain

## Re: 16 bits is more than enough

##### Reply #14 – 2022-08-10 23:06:45
Quote
CDs only make about 22Hz per left and right channel.
The frequency is limited to half of the sample rate (44,100 samples per second) and this is unrelated to bit depth.

Digital audio is quantized in two dimensions, amplitude and time.

## Re: 16 bits is more than enough

##### Reply #16 – 2022-08-11 00:25:09
In video don't forget about HDR and wide gamut, where 8 bits per channel would be far from enough.

## Re: 16 bits is more than enough

##### Reply #17 – 2022-08-11 10:39:54
What I would really like to know
What is up with all the oversized images on this forum lately?
Yeah man, I'm on my 1990s DX2-66 and my 14" crt screen cannot handle those.

## Re: 16 bits is more than enough

##### Reply #18 – 2022-08-12 20:22:48
Under laboratory conditions (with higher than typical LCD brightness levels) it was found that the human eye can see somewhere between 600-1000 shades of gray, so it is necessary to have a minimum of 10 bits per channel (1023 levels) for HDR picture quality. It's not that hard to see banding in undithered 24 bit images where the green channel (wavelengths our eyes are most sensitive to) needs high dynamic range.

There are similar limitations in auditory precision in hearing, considering the most transparent psychoacoustic compression is generally limited to an accuracy of 8 bits significant digits and transparent LossyFLAC/etc goes down to 8 bits significant digits, that 16-bit "half" precision is more than enough to fool human hearing with more dynamic range than 16-bit audio. So you can encode masters in less than 16 bits if it's floating point.

## Re: 16 bits is more than enough

##### Reply #19 – 2022-08-12 22:47:30
Under laboratory conditions (with higher than typical LCD brightness levels) it was found that the human eye can see somewhere between 600-1000 shades of gray, so it is necessary to have a minimum of 10 bits per channel (1023 levels) for HDR picture quality. It's not that hard to see banding in undithered 24 bit images where the green channel (wavelengths our eyes are most sensitive to) needs high dynamic range.

But we can imagine that in the future we'll put fake windows / screen on a wall to replicate a view to the exterior (with some "AI" to show a view relatively to our position - imagine that!). To simulate full range from deep dark night, moon light, to full sunlight, This will need a bigger range than 1024 levels of lumens per cm2 even if the eye is limited to 1024 ones, because of the pupils. I have no idea of the range it will need. Perhaps 16 bits will not be enough

Quote

There are similar limitations in auditory precision in hearing, considering the most transparent psychoacoustic compression is generally limited to an accuracy of 8 bits significant digits and transparent LossyFLAC/etc goes down to 8 bits significant digits, that 16-bit "half" precision is more than enough to fool human hearing with more dynamic range than 16-bit audio. So you can encode masters in less than 16 bits if it's floating point.

Converting a 16 bits signal to 8 bits is not really a "compression".
A sample in int16 or float16 have the same number of "shades".

## Re: 16 bits is more than enough

##### Reply #20 – 2022-08-12 23:30:53
Converting a 16 bits signal to 8 bits is not really a "compression".

It... literally is? By a factor of 2, in fact.

## Re: 16 bits is more than enough

##### Reply #21 – 2022-08-13 01:45:23
Converting a 16 bits signal to 8 bits is not really a "compression".

It... literally is? By a factor of 2, in fact.

So call it a division by a factor of 256 but certainly not compression. If you compress an audio file with FLAC it keep its 16 bits depth. Same thing if you "compress" it to have a more or less same amplitude all along the track with an audio digital compressor, it's still 16 bits after the process.

## Re: 16 bits is more than enough

##### Reply #22 – 2022-08-13 10:00:12
An experimental format I made previously. Not really floating point but some sort of log approximation, with 8 or 12 bits quantization.
https://hydrogenaud.io/index.php/topic,121181.msg1005031.html#msg1005031

Half-float contains negative zero, infinity and NaN, so in practice the usable values are fewer than 16-bit integer.

## Re: 16 bits is more than enough

##### Reply #23 – 2022-08-13 12:52:59
An experimental format I made previously. Not really floating point but some sort of log approximation, with 8 or 12 bits quantization.
https://hydrogenaud.io/index.php/topic,121181.msg1005031.html#msg1005031

Half-float contains negative zero, infinity and NaN, so in practice the usable values are fewer than 16-bit integer.

The range of values are not the same but the total number of distinct value possible is the same.

For integer format: 2**32 = 4,294,967,296

For real, float, fixed, etc.. whatever the (sign, expo, etc..) layout:

fraction => 2**24 = 16,777,216
expo => 2**8 = 256

fraction * expo = 4,294,967,296 like for a int32 ou uint32

## Re: 16 bits is more than enough

##### Reply #24 – 2022-08-13 15:08:02
To elaborate, "usable values" means usable finite and numeric values, not range and other things, I did not mention range in the first place, and your examples don't include half-float as well:
https://evanw.github.io/float-toy/
NaNs and infinites occupied some values, unless repurposed to represent audio sample values, but doing so will break the specs.
Total discrete values regardless of meaning of course are same in 16-bit integer and half-float, this does not need special mention obviously.

For example, the 8 and 12-bit companding formats I mentioned in my previous post don't contain negative zero, NaNs and infinities.