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This article makes the same mistake that is done frequently with video. So, let’s look at a similar issue with video. Your display is likely only 720p, or 1080

This article makes the same mistake that is done frequently with video. So, let’s look at a similar issue with video. Your display is likely only 720p, or 1080p, but a 4K video on youtube will still look a lot better, although technically it should have no visible difference. But the reality is, we don’t get uncompressed video, or uncompressed audio. We have a choice between audio or video compressed with lossy codecs, at 16bit/44kHz or 16bit/96kHz, or 4:2:0 video at 1080p or 4:2:0 video at 4K. And just like you need 4K 4:2:0 mp4 video to get even close to the quality of uncompressed 1080p 4:4:4 video, you also need far higher sampling rate and depth of highly compressed audio to get a quality similar to 16bit/44.1kHz PCM. That’s the real reason why 24bit/192kHz AAC downloads were even discussed.

TazeTSchnitzel 9y ago
> Your display is likely only 720p, or 1080p, but a 4K video on youtube will still look a lot better, although technically it should have no visible difference. Not at all, bitrate differences are audible. > And just like you need 4K 4:2:0 mp4 video to get even close to the quality of uncompressed 1080p 4:4:4 video, you also need far higher sampling rate and depth of highly compressed audio to get a quality similar to 16bit/44.1kHz PCM. …how so?
- kuschku 9y ago
  > Not at all, bitrate differences are audible. Even with the same bitrate, you’ll need 4K video to get quality comparable to uncompressed 1080p. For example, mp4 defines that the brightness channel Y should be stored with full resolution, and the color channels Pb Pr should be stored at half resolution. So in a 4K mp4 video at lossless bitrate, the actual colors will only be stored at 1080p. This functionality is called Chroma Subsampling. Audio Codecs do something very similar, causing these exact issues.
  - astrange 9y ago
    It doesn't matter what resolution the color is stored at, as long as the high frequencies are the same as the Y channel. You won't have lost anything. Of course, cross-channel intra prediction would work better[1] but 4:2:0 is pretty good quality considering you can throw out 3/4 the pixels. [1] https://people.xiph.org/~unlord/spie_cfl.pdf https://people.xiph.org/~unlord/spie_cfl.pdf
    - kuschku 9y ago
      That’s again the same issue. Nice theory, and theoretically is true, but all real algorithms also subsample high frequencies, and scale them back up with nearest-neighbor. The same issue happens with audio. Nice theory, completely broken realistic implementations.
      - astrange 9y ago
        It's true that nearest neighbor is bad, but the important part is the YUV->RGB conversion. It distributes the missing high frequencies out of the Y channel into all three RGB images.
anyfoo 9y ago
The article was arguing about 24bit/192kHz digital audio, not about what codecs do or don't do with it. If you need 24bit/192kHz with both inaudible frequencies and inaudible dynamic steps to make 16bit/48kHz music sound better at the same bitrate, then the parameters you've given to your codec suck. Same for video. YouTube very likely allocates more bandwidth for 4k video than would be required for equivalent quality at lower resolutions, assuming that you are interested in higher overall quality (e.g. less artifacts) if you go through the trouble of 4k video. That's a conscious choice, not a technical necessity.
- kuschku 9y ago
  With video it’s not about bitrate, but Chroma Subsampling. Basically, mp4 and webm video only encodes the brightness channel Y at full resolution, and the color channels Pb Pr at half resolution. You can’t have mp4 or webm video without Chroma Subsampling, it’s defined in the codecs standard. Audio codecs do something very similar, cutting off a large percentage of the higher and lower frequencies. mp3 (and AAC) for example allocate almost the entire space for the frequencies around 4 to 8kHz, and drops then drops a certain percentage of the upper frequencies entirely. The article talks about uncompressed audio, but the topic he responds to is Apple choosing to sell 24bit/192kHz AAC lossy compressed audio. The author of the article is responding to a business decision, which has nothing to do with the actual topic of the article.
  - astrange 9y ago
    Chroma subsampling is optional in AVC and HEVC and IMO we should stop using it for 480p or smaller video. Not because the information is important - color is usually bandlimited - but because all the decoders use the worst resampling algorithm to display it.
  - cellularmitosis 9y ago
    Funny anecdote, I first became aware of this while watching Aliens. When the aliens cut the power and the set is bathed in the red of the emergency backup lights, the resolution of the video appears much worse.
- 9y ago
mcbits 9y ago
Suppose you have a 5 Mbps data budget, 1080p display, and 4k source material. You will get better quality by first downsampling the 4k to 1080p and then compressing and distributing the result. If you compress and distribute the 4k, followed by downsampling to display at 1080p, you cannot recover the color and/or motion information that was lost in order to fit all of those pixels into 5 Mbps. However, if you have a 20 Mbps budget for the 4k to account for having 4 times as much original data, then there shouldn't be much of a difference in the downsampled 1080p video (ignoring peculiarities of the codec). All this is not very relevant to the audio issue being discussed. It would be relevant if it were physically impossible to perceive the difference between 1080p and 4k video, and if watching 4k video potentially caused optical illusions. In that case, the only reason to prefer the 20 Mbps 4k stream would be if you planned to edit, mix, or zoom around in the video instead of simply watching it. When it comes to audio, since size isn't as much of a concern as video, in most cases I would say "maybe I'll want to edit it someday" is strong enough reason to get the 24/192 material at a correspondingly high bitrate if it's available.
- kuschku 9y ago
  But that’s the exact issue that this entire article is missing! It’s all about peculiarities of the codec! The issue at hand is apple selling 24bit/192kHz versions of lossy AAC compressed files, compared to 16bit/44.1kHz versions of AAC files. And the issue I was comparing with video was the same – with video, codecs enforce Chroma Subsampling, where the resolution for color is half that of the actual imagery. In the same way, AAC and mp3 heavily reduce the bandwidth for the upper half of the frequency spectrum, spending like 90% of their available bandwidth on the lower half (with 44.1kHz, they prioritize the range between 4 and 8kHz, specifically, where speech is). The entire topic is if using a codec that specifically cuts away the lower and upper parts of the frequency spectrum, increasing the frequency spectrum can improve quality. And yes, it does. Apple is selling AAC, not WAV. Which makes the entire article useless. Yes, we should all focus on replacing 16bit/44.1kHz AAC with 16bit/44.1kHz FLAC instead of 24bit/192kHz AAC, and we all should focus on replacing 4:2:0 1080p mp4 with 4:4:4 1080p mp4 instead of 4:2:0 4K mp4 (the chroma subsampling issue I mentioned). But that’s not the reality we live in, and given the choice between 16bit/44.1kHz AAC and 24bit/192kHz AAC, I’ll choose the second.
BuuQu9hu 9y ago
You're getting downvoted but you're absolutely correct. The question is NOT > Does 24/192 sound better than 16/44.1? The answer is no. The ACTUAL question is > Does COMPRESSED 24/192 sound better than COMPRESSED 16/44.1? The answer is yes (specifically in the case of mp3, aac, etc).

TazeTSchnitzel 9y ago

> Your display is likely only 720p, or 1080p, but a 4K video on youtube will still look a lot better, although technically it should have no visible difference. Not at all, bitrate differences are audible. > And just like you need 4K 4:2:0 mp4 video to get even close to the quality of uncompressed 1080p 4:4:4 video, you also need far higher sampling rate and depth of highly compressed audio to get a quality similar to 16bit/44.1kHz PCM. …how so?

kuschku 9y ago
> Not at all, bitrate differences are audible. Even with the same bitrate, you’ll need 4K video to get quality comparable to uncompressed 1080p. For example, mp4 defines that the brightness channel Y should be stored with full resolution, and the color channels Pb Pr should be stored at half resolution. So in a 4K mp4 video at lossless bitrate, the actual colors will only be stored at 1080p. This functionality is called Chroma Subsampling. Audio Codecs do something very similar, causing these exact issues.
- astrange 9y ago
  It doesn't matter what resolution the color is stored at, as long as the high frequencies are the same as the Y channel. You won't have lost anything. Of course, cross-channel intra prediction would work better[1] but 4:2:0 is pretty good quality considering you can throw out 3/4 the pixels. [1] https://people.xiph.org/~unlord/spie_cfl.pdf https://people.xiph.org/~unlord/spie_cfl.pdf
  - kuschku 9y ago
    That’s again the same issue. Nice theory, and theoretically is true, but all real algorithms also subsample high frequencies, and scale them back up with nearest-neighbor. The same issue happens with audio. Nice theory, completely broken realistic implementations.
    - astrange 9y ago
      It's true that nearest neighbor is bad, but the important part is the YUV->RGB conversion. It distributes the missing high frequencies out of the Y channel into all three RGB images.

anyfoo 9y ago

The article was arguing about 24bit/192kHz digital audio, not about what codecs do or don't do with it. If you need 24bit/192kHz with both inaudible frequencies and inaudible dynamic steps to make 16bit/48kHz music sound better at the same bitrate, then the parameters you've given to your codec suck. Same for video. YouTube very likely allocates more bandwidth for 4k video than would be required for equivalent quality at lower resolutions, assuming that you are interested in higher overall quality (e.g. less artifacts) if you go through the trouble of 4k video. That's a conscious choice, not a technical necessity.

kuschku 9y ago
With video it’s not about bitrate, but Chroma Subsampling. Basically, mp4 and webm video only encodes the brightness channel Y at full resolution, and the color channels Pb Pr at half resolution. You can’t have mp4 or webm video without Chroma Subsampling, it’s defined in the codecs standard. Audio codecs do something very similar, cutting off a large percentage of the higher and lower frequencies. mp3 (and AAC) for example allocate almost the entire space for the frequencies around 4 to 8kHz, and drops then drops a certain percentage of the upper frequencies entirely. The article talks about uncompressed audio, but the topic he responds to is Apple choosing to sell 24bit/192kHz AAC lossy compressed audio. The author of the article is responding to a business decision, which has nothing to do with the actual topic of the article.
- astrange 9y ago
  Chroma subsampling is optional in AVC and HEVC and IMO we should stop using it for 480p or smaller video. Not because the information is important - color is usually bandlimited - but because all the decoders use the worst resampling algorithm to display it.
- cellularmitosis 9y ago
  Funny anecdote, I first became aware of this while watching Aliens. When the aliens cut the power and the set is bathed in the red of the emergency backup lights, the resolution of the video appears much worse.
9y ago

mcbits 9y ago

Suppose you have a 5 Mbps data budget, 1080p display, and 4k source material. You will get better quality by first downsampling the 4k to 1080p and then compressing and distributing the result. If you compress and distribute the 4k, followed by downsampling to display at 1080p, you cannot recover the color and/or motion information that was lost in order to fit all of those pixels into 5 Mbps. However, if you have a 20 Mbps budget for the 4k to account for having 4 times as much original data, then there shouldn't be much of a difference in the downsampled 1080p video (ignoring peculiarities of the codec). All this is not very relevant to the audio issue being discussed. It would be relevant if it were physically impossible to perceive the difference between 1080p and 4k video, and if watching 4k video potentially caused optical illusions. In that case, the only reason to prefer the 20 Mbps 4k stream would be if you planned to edit, mix, or zoom around in the video instead of simply watching it. When it comes to audio, since size isn't as much of a concern as video, in most cases I would say "maybe I'll want to edit it someday" is strong enough reason to get the 24/192 material at a correspondingly high bitrate if it's available.

kuschku 9y ago
But that’s the exact issue that this entire article is missing! It’s all about peculiarities of the codec! The issue at hand is apple selling 24bit/192kHz versions of lossy AAC compressed files, compared to 16bit/44.1kHz versions of AAC files. And the issue I was comparing with video was the same – with video, codecs enforce Chroma Subsampling, where the resolution for color is half that of the actual imagery. In the same way, AAC and mp3 heavily reduce the bandwidth for the upper half of the frequency spectrum, spending like 90% of their available bandwidth on the lower half (with 44.1kHz, they prioritize the range between 4 and 8kHz, specifically, where speech is). The entire topic is if using a codec that specifically cuts away the lower and upper parts of the frequency spectrum, increasing the frequency spectrum can improve quality. And yes, it does. Apple is selling AAC, not WAV. Which makes the entire article useless. Yes, we should all focus on replacing 16bit/44.1kHz AAC with 16bit/44.1kHz FLAC instead of 24bit/192kHz AAC, and we all should focus on replacing 4:2:0 1080p mp4 with 4:4:4 1080p mp4 instead of 4:2:0 4K mp4 (the chroma subsampling issue I mentioned). But that’s not the reality we live in, and given the choice between 16bit/44.1kHz AAC and 24bit/192kHz AAC, I’ll choose the second.

BuuQu9hu 9y ago

You're getting downvoted but you're absolutely correct. The question is NOT > Does 24/192 sound better than 16/44.1? The answer is no. The ACTUAL question is > Does COMPRESSED 24/192 sound better than COMPRESSED 16/44.1? The answer is yes (specifically in the case of mp3, aac, etc).