8 ms·

This like arguing that aspect ratios are stupid and wrong because sometimes they apply to a screen which is really big and sometimes it's really small and somet

This like arguing that aspect ratios are stupid and wrong because sometimes they apply to a screen which is really big and sometimes it's really small and sometimes they apply to a physical print or a photo or a billboard or a vintage TV and sometimes it's a jpg or a PNG. Aspect ratio is a ratio. It can be a ratio between pixel counts, or between print dimensions, or physical display dimensions. All of which are useful in their own way, none of which are directly comparable, all of which are understandable in context. dB is the same. It's a ratio split into convenient steps - more convenient than Bels would be - that compares two quantities. The quantities can be measured in different units. The units are implied by the context. The only mild confusion is the relationship between voltage and power ratios. But that's a minor wrinkle, not a showstopping intellectual challenge.

sandblast 1y ago
Ratios are numbers. They are literally just fractions. No one argues that the numbers don't make sense because you can have different units. But that's what units are for – to know what does the preceding number refer to. Why have a unit that doesn't give you full information?
- more-nitor 1y ago
  this if a TV seller went bonkers and only said "it's 10:16", can you guess the actual size of that TV?
  - jhbadger 1y ago
    But that's not what is being expressed. You might as well complain that the ratio doesn't give you information on the price, weight, or power usage of the TV.
gwd 1y ago
> Aspect ratio is a ratio. Right, but in this case they only give you one of the two numbers. Imagine being told that your TV had an aspect ration of ":16", and you just have to magically know what the other number means in the context. And sometimes ":16" actually means ":4", because quadratic mumble mumble, and sometimes the number is scaled according to some other "how big it seems to humans" factor; all of which you also just have to know in context.
- megous 1y ago
  Ratio is just a single number. 4:3 can be expressed as 1.3333~ and it just says how much bigger one number is compared to another. RE: Yes, I was able to read and understand the article. I also have 8 years of EE. Ratio is still a single number in the end. You can have an actual size of a monitor 1600 x 1200 and the ratio of sides is 1600/1200, which is just a single number. You can express it in multiple ways. You still need at least one size + understanding of what the aspect ratio is used to describe in a particular situation (units (mm, px, ...), ...) to be able to calculate the complete dimensions of a monitor screen. Same issue with % or ppm, or whatever. You always need a defintition to understand what the numbers are abstracting in any particular situation.
  - gwd 1y ago
    Sure, and 10db means "10x more power". But: 1. 10x more power than what? It changes, and you Just Have to Know. 2. It's 10x more power; so if you're measuring power, like pascals, then 10db means 10x more pascals. But if you're measuring something like voltage, then it's not 10x more voltage, it's something else. 3. And if you're talking about sound, you may be talking about objective power; or you might be talking about how much more powerful it seems to humans.
    - nayuki 1y ago
      > Sure, and 10db means "10x more power". But: 1. 10x more power than what? It changes, and you Just Have to Know. That gives me an idea - explicitly state the basis and multiply. So the current notation "3 dBm" should instead be "1 mW × 3 dB". Furthermore, any addition in the logarithmic domain must be grouped, like: "3 dBm + 5 dB" --> "1 mW × (3 dB + 5 dB)".
  - ants_a 1y ago
    So my display aspect ratio is 2.5dB. Or is it 5dB because it's not measuring power?
- dagw 1y ago
  Imagine being told that your TV had an aspect ration of ":16" We kind of have that with people talking about a screen or image being "2k" and then expect you to infer what the actual resolution and aspect ratio is from context.
pwdisswordfishz 1y ago
Why, you're right: aspect ratios are stupid because people often don't bother distinguishing between SAR, PAR and DAR, leading to lots of confusion. And sometimes even mistake the ratio of pixel densities for the pixel aspect ratio: https://trac.ffmpeg.org/ticket/11279 https://trac.ffmpeg.org/ticket/11279 https://trac.ffmpeg.org/ticket/11284 https://trac.ffmpeg.org/ticket/11284
- sgarland 1y ago
  Nothing better than spending hours encoding something, only to discover you got one of those wrong.
svara 1y ago
Respectfully, I'm not sure you fully understand how dB is used. The analogy to aspect ratios only works for one of multiple uses of decibel. dB SPL and dB(A) are not ratios, they're absolute. You can derive them from a ratio and a reference level, but the former can be expressed in Pascal and the latter relates to Pascals after applying a perceptual correction function. Similarly, dBm can be expressed as an absolute potential in Volt. And then you've got the cases where it really just is a ratio (one of two possibilities). You'll see all of these called "decibels". You see why people are irritated?
- wisty 1y ago
  Yep you have dB for a ratio, and dB SPL as a physical unit. Just as the article says. And yeah, the issue is when people forget to use physical units, like if they say it's 30 degrees outside amd not saying C F or K or latitude. The historical context is a bit meaningless as well since the main application for the OG dB is 101 classes.
- hgomersall 1y ago
  Stop saying "one of two possibilities". It isn't. A dB is a power ratio. The fact that you can describe that in terms of voltage ratio is a simple reflection of the fact that power ratios can be described as a voltage ratio squared. When talking about voltage ratios directly from dB you're just short circuiting the necessary square root.
sgarland 1y ago
> The units are implied by the context. This is the absurd part. There do exist other ratios that masquerade as units, e.g. specific gravity, and its meaning also changes depending on what you’re using it for - liquids are compared to pure water at 4 C, gases are compared to air at 20 C. As the parent comment points out, you can get used to things with experience. That doesn’t make them any less absurd. Look at Fahrenheit, for example. I’m American, and I still think it’s absurd, but because I’m extremely used to it, it feels natural.
- Aachen 1y ago
  Coulomb? In a discussion about units, leaving out the degree word or symbol made me initially try to parse it as that you must mean it literally, though context quickly makes clear that isn't the case ^^'
  - sgarland 1y ago
    Fair point. I did briefly think about finding the Unicode symbol on my phone. My bad.
- tzs 1y ago
  > Look at Fahrenheit, for example. I’m American, and I still think it’s absurd, but because I’m extremely used to it, it feels natural. What do you find absurd about Fahrenheit? If it is that its 0 point is not absolute 0 then I think you can make a good case, at least for scientific work. It's a bit harder to make the case for absolute 0 being the 0 point a scale for ordinary day to day use since all temperatures most people deal with will be 3 digit numbers (and making you degree large won't help because people will still need 3 digit number--they just won't be integers any more). If you find it absurd compared to Celsius then I think it is hard to make a convincing case. They are both scales with a 0 point way above absolute 0, differing only on where they put their 0 point and the size of the degree. (They originally differed on direction, with Celsius putting 0 at the boiling point of water and setting the degree size so that water froze at 100, but Celsius soon came to his sense and flipped so the numbers went up as it got hotter). Fahrenheit set 0 at the coldest temperature he could make in his lab and tried to set 100 at body temperature. Celsius (once he got the direction fixed) set 0 at water freezing and 100 at water boiling. That gives Fahrenheit a smaller degree and puts the range of temperatures most people deal with most of the time above 0. Celsius made it easier to memorize two temperatures that are very significant in many human activities, namely the freezing point of water and the boiling point of water (although the latter is probably less important...generally most people only deal with boiling water when they are trying to boil water and don't need to care about the temperature. It's not like freezing which can happen naturally and so people often need to monitor temperature to find out if there is danger of freezing). But that 0 point in Celsius means that a lot of people have to regularly deal with negative temperature which is a little annoying. The metric system chose Celsius, but I've not been able to find any compelling technical reason for that. A metric system with Fahrenheit would have fine too. Note that unlike mass, length, area, and volume units pre-metric systems generally only had one temperature unit. There was nothing in temperature like miles, yards, inches, feet, furlongs, etc. for length and gallons, pints, cups, etc. for volume. A system that went with one single length unit (the meter) and one single volume unit (the liter) and then derived larger and smaller units from those using consistent ratios and prefixes that were the same across different types of units was a massive simplification. I asked an LLM why metric went with Celsius and got a lot of circular reasons. For example it cited that various thermodynamic forumals would not work with F degrees because the Boltzman constant is defined in the SI system using K. But the Boltzman constant is defined that way because SI uses the metric system. In an F based metric system the Boltzman constant would be defined in R and everything would work fine. The non-circular reasons it suggested were also not satisfactory. One was that C was more common than F in Europe at the time the metric system was created, which technically does answer the question I asked but then raises the question of why C became more common pre-metric. It also suggested that having water freeze at 0 and boil at 100 fits in better with a decimal system which doesn't really make a lot of sense. As for why C became more popular than F pre-metric it suggests that the 0 and 100 points were easier to reproduce. Fahrenheit's choice of body temperature for the 100 point was definitely a mistake as it is too fuzzy (it was even dumber than metric's initial choice for the meter as 1/10000000th of the distance from the distance from the North Pole to the equator along the meridian passing through Paris). Freezing and boiling of water do take some care to use (you need to control pressure and contaminants) but are going to be more consistent that body temperature. But there is no reason I can see that the fuzziness in Fahrenheit's 100 point couldn't have been fixed by simply changing the defining points from 0 and 100 to water freezes at 32 and boils at 212. Yes, it is not as easy to memorize as 0 and 100 but does let us have a scale where most temperatures dealt with by most people most of the time are 2 or 3 digit positive integers.

sandblast 1y ago

Ratios are numbers. They are literally just fractions. No one argues that the numbers don't make sense because you can have different units. But that's what units are for – to know what does the preceding number refer to. Why have a unit that doesn't give you full information?

more-nitor 1y ago
this if a TV seller went bonkers and only said "it's 10:16", can you guess the actual size of that TV?
- jhbadger 1y ago
  But that's not what is being expressed. You might as well complain that the ratio doesn't give you information on the price, weight, or power usage of the TV.

gwd 1y ago

> Aspect ratio is a ratio. Right, but in this case they only give you one of the two numbers. Imagine being told that your TV had an aspect ration of ":16", and you just have to magically know what the other number means in the context. And sometimes ":16" actually means ":4", because quadratic mumble mumble, and sometimes the number is scaled according to some other "how big it seems to humans" factor; all of which you also just have to know in context.

megous 1y ago
Ratio is just a single number. 4:3 can be expressed as 1.3333~ and it just says how much bigger one number is compared to another. RE: Yes, I was able to read and understand the article. I also have 8 years of EE. Ratio is still a single number in the end. You can have an actual size of a monitor 1600 x 1200 and the ratio of sides is 1600/1200, which is just a single number. You can express it in multiple ways. You still need at least one size + understanding of what the aspect ratio is used to describe in a particular situation (units (mm, px, ...), ...) to be able to calculate the complete dimensions of a monitor screen. Same issue with % or ppm, or whatever. You always need a defintition to understand what the numbers are abstracting in any particular situation.
- gwd 1y ago
  Sure, and 10db means "10x more power". But: 1. 10x more power than what? It changes, and you Just Have to Know. 2. It's 10x more power; so if you're measuring power, like pascals, then 10db means 10x more pascals. But if you're measuring something like voltage, then it's not 10x more voltage, it's something else. 3. And if you're talking about sound, you may be talking about objective power; or you might be talking about how much more powerful it seems to humans.
  - nayuki 1y ago
    > Sure, and 10db means "10x more power". But: 1. 10x more power than what? It changes, and you Just Have to Know. That gives me an idea - explicitly state the basis and multiply. So the current notation "3 dBm" should instead be "1 mW × 3 dB". Furthermore, any addition in the logarithmic domain must be grouped, like: "3 dBm + 5 dB" --> "1 mW × (3 dB + 5 dB)".
- ants_a 1y ago
  So my display aspect ratio is 2.5dB. Or is it 5dB because it's not measuring power?
dagw 1y ago
Imagine being told that your TV had an aspect ration of ":16" We kind of have that with people talking about a screen or image being "2k" and then expect you to infer what the actual resolution and aspect ratio is from context.

pwdisswordfishz 1y ago

Why, you're right: aspect ratios are stupid because people often don't bother distinguishing between SAR, PAR and DAR, leading to lots of confusion. And sometimes even mistake the ratio of pixel densities for the pixel aspect ratio: https://trac.ffmpeg.org/ticket/11279 https://trac.ffmpeg.org/ticket/11279 https://trac.ffmpeg.org/ticket/11284 https://trac.ffmpeg.org/ticket/11284

sgarland 1y ago
Nothing better than spending hours encoding something, only to discover you got one of those wrong.

svara 1y ago

Respectfully, I'm not sure you fully understand how dB is used. The analogy to aspect ratios only works for one of multiple uses of decibel. dB SPL and dB(A) are not ratios, they're absolute. You can derive them from a ratio and a reference level, but the former can be expressed in Pascal and the latter relates to Pascals after applying a perceptual correction function. Similarly, dBm can be expressed as an absolute potential in Volt. And then you've got the cases where it really just is a ratio (one of two possibilities). You'll see all of these called "decibels". You see why people are irritated?

wisty 1y ago
Yep you have dB for a ratio, and dB SPL as a physical unit. Just as the article says. And yeah, the issue is when people forget to use physical units, like if they say it's 30 degrees outside amd not saying C F or K or latitude. The historical context is a bit meaningless as well since the main application for the OG dB is 101 classes.
hgomersall 1y ago
Stop saying "one of two possibilities". It isn't. A dB is a power ratio. The fact that you can describe that in terms of voltage ratio is a simple reflection of the fact that power ratios can be described as a voltage ratio squared. When talking about voltage ratios directly from dB you're just short circuiting the necessary square root.

sgarland 1y ago

> The units are implied by the context. This is the absurd part. There do exist other ratios that masquerade as units, e.g. specific gravity, and its meaning also changes depending on what you’re using it for - liquids are compared to pure water at 4 C, gases are compared to air at 20 C. As the parent comment points out, you can get used to things with experience. That doesn’t make them any less absurd. Look at Fahrenheit, for example. I’m American, and I still think it’s absurd, but because I’m extremely used to it, it feels natural.

Aachen 1y ago
Coulomb? In a discussion about units, leaving out the degree word or symbol made me initially try to parse it as that you must mean it literally, though context quickly makes clear that isn't the case ^^'
- sgarland 1y ago
  Fair point. I did briefly think about finding the Unicode symbol on my phone. My bad.
tzs 1y ago
> Look at Fahrenheit, for example. I’m American, and I still think it’s absurd, but because I’m extremely used to it, it feels natural. What do you find absurd about Fahrenheit? If it is that its 0 point is not absolute 0 then I think you can make a good case, at least for scientific work. It's a bit harder to make the case for absolute 0 being the 0 point a scale for ordinary day to day use since all temperatures most people deal with will be 3 digit numbers (and making you degree large won't help because people will still need 3 digit number--they just won't be integers any more). If you find it absurd compared to Celsius then I think it is hard to make a convincing case. They are both scales with a 0 point way above absolute 0, differing only on where they put their 0 point and the size of the degree. (They originally differed on direction, with Celsius putting 0 at the boiling point of water and setting the degree size so that water froze at 100, but Celsius soon came to his sense and flipped so the numbers went up as it got hotter). Fahrenheit set 0 at the coldest temperature he could make in his lab and tried to set 100 at body temperature. Celsius (once he got the direction fixed) set 0 at water freezing and 100 at water boiling. That gives Fahrenheit a smaller degree and puts the range of temperatures most people deal with most of the time above 0. Celsius made it easier to memorize two temperatures that are very significant in many human activities, namely the freezing point of water and the boiling point of water (although the latter is probably less important...generally most people only deal with boiling water when they are trying to boil water and don't need to care about the temperature. It's not like freezing which can happen naturally and so people often need to monitor temperature to find out if there is danger of freezing). But that 0 point in Celsius means that a lot of people have to regularly deal with negative temperature which is a little annoying. The metric system chose Celsius, but I've not been able to find any compelling technical reason for that. A metric system with Fahrenheit would have fine too. Note that unlike mass, length, area, and volume units pre-metric systems generally only had one temperature unit. There was nothing in temperature like miles, yards, inches, feet, furlongs, etc. for length and gallons, pints, cups, etc. for volume. A system that went with one single length unit (the meter) and one single volume unit (the liter) and then derived larger and smaller units from those using consistent ratios and prefixes that were the same across different types of units was a massive simplification. I asked an LLM why metric went with Celsius and got a lot of circular reasons. For example it cited that various thermodynamic forumals would not work with F degrees because the Boltzman constant is defined in the SI system using K. But the Boltzman constant is defined that way because SI uses the metric system. In an F based metric system the Boltzman constant would be defined in R and everything would work fine. The non-circular reasons it suggested were also not satisfactory. One was that C was more common than F in Europe at the time the metric system was created, which technically does answer the question I asked but then raises the question of why C became more common pre-metric. It also suggested that having water freeze at 0 and boil at 100 fits in better with a decimal system which doesn't really make a lot of sense. As for why C became more popular than F pre-metric it suggests that the 0 and 100 points were easier to reproduce. Fahrenheit's choice of body temperature for the 100 point was definitely a mistake as it is too fuzzy (it was even dumber than metric's initial choice for the meter as 1/10000000th of the distance from the distance from the North Pole to the equator along the meridian passing through Paris). Freezing and boiling of water do take some care to use (you need to control pressure and contaminants) but are going to be more consistent that body temperature. But there is no reason I can see that the fuzziness in Fahrenheit's 100 point couldn't have been fixed by simply changing the defining points from 0 and 100 to water freezes at 32 and boils at 212. Yes, it is not as easy to memorize as 0 and 100 but does let us have a scale where most temperatures dealt with by most people most of the time are 2 or 3 digit positive integers.