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> we are the first to make it work for 48 kHz sampled stereo audio (i.e., CD quality) "CD quality" is 44.1khz over 16bit. > We achieve an approximate 10x comp

by guggle 4y ago

> we are the first to make it work for 48 kHz sampled stereo audio (i.e., CD quality) "CD quality" is 44.1khz over 16bit. > We achieve an approximate 10x compression rate compared with MP3 at 64 kbps, without a loss of quality. but then later: > The key to lossy compression is to identify changes that will not be perceivable by humans

augustuspolius 4y ago
It's quite amazing how they can build something so ingenious and yet make such a glaring mistake in the announcement post (48 kHz CD quality). On your second point: they probably meant that there is no loss in perceived quality, of course it's a lossy algorithm. 6kbps sound demo is really impressive! Initially I was turned off by aliasing artifacts (hiss) but to be fair 6kbps is a really really low bitrate.
- guggle 4y ago
  It is impressive, but it's also not something I would want to use for music listening. I guess the "10x" goal makes for an impressive chart, but I'd like to know what are the more realistic goals and gains.
  - augustuspolius 4y ago
    The interesting part to me was that they used specifically a 64kbps example, not a higher bitrate that would be more appropriate for music listening. Just speculating, but if they managed to get 10x higher compression rate compared to 64kbps MP3, could they achieve an even higher compression rate when compared to 320kbps MP3? If the algorithm is so good that it can compress audio down to 6kbps with just a few artifacts, would it sound almost good at 12kbps? 24kbps? Between this effort and the recently announced Google-led multi-channel/immersive audio codec initiative, I am pretty excited about the future of audio streaming and distribution.
    - brokenmachine 4y ago
      >recently announced Google-led multi-channel/immersive audio codec initiative Link?
    - beardyw 4y ago
      > they used specifically a 64kbps example, not a higher bitrate that would be more appropriate for music listening. ... but only if you are a bat.
      - genewitch 4y ago
        Bitrate as it pertains to the size is the purpose of all of this.
  - bongobingo1 4y ago
    > not something I would want to use for music listening The flute in particular suffers quite a lot and the triangle disappears completely!
  - Workaccount2 4y ago
    It is something you would want though if you are hosting content with audio consumed by people who aren't paying attention to audio quality.
- Dwedit 4y ago
  Because writeups are done at the last second, rather than as part of the project.
bscphil 4y ago
> While such techniques have been explored before for speech, we are the first to make it work for 48 kHz sampled stereo audio (i.e., CD quality), which is the standard for music distribution. Reading this extremely charitably, I think the contrast is supposed to be to speech which is normally uses much smaller sample rates. E.g. AMR-WB samples at 16 kHz. Speex, back in the day, supported up to 32 kHz. Full quality digitally distributed audio is often sampled at 48 kHz (e.g. Opus - the default audio codec on YouTube and many other sources), so I think "CD quality" is just supposed to emphasize that it's full-band rather than wide band or narrow band.
earthnail 4y ago
Since there is no perceptual difference to humans between 44.1 and 48 kHz, the statement about CD quality is perfectly fine - even more so as they operate on the higher sample rate. Most research in that field operates at 16kHz. Enough for most speech applications, not enough for CD quality. In general, CD quality in this field means a high enough sample rate that you can play all audible frequencies.
- rzzzt 4y ago
  They didn't specify bit depth either. I understand all of this reads like pointless pedantry, but a) it feels good indulging in it b) certain word combinations (such as "CD quality") have meanings backed by broad consensus, please use them responsibly so readers do not have to overexert their loose interpretation muscle. If they mean wide band, say wide band, noone will bat an eye.
- ihatepython 4y ago
  No, CD quality means 44.1 kHz 16-bit. DVD quality would be 48 kHz. Higher sample rate does not necessary mean higher quality

by guggle 4y ago

augustuspolius 4y ago

It's quite amazing how they can build something so ingenious and yet make such a glaring mistake in the announcement post (48 kHz CD quality). On your second point: they probably meant that there is no loss in perceived quality, of course it's a lossy algorithm. 6kbps sound demo is really impressive! Initially I was turned off by aliasing artifacts (hiss) but to be fair 6kbps is a really really low bitrate.

guggle 4y ago
It is impressive, but it's also not something I would want to use for music listening. I guess the "10x" goal makes for an impressive chart, but I'd like to know what are the more realistic goals and gains.
- augustuspolius 4y ago
  The interesting part to me was that they used specifically a 64kbps example, not a higher bitrate that would be more appropriate for music listening. Just speculating, but if they managed to get 10x higher compression rate compared to 64kbps MP3, could they achieve an even higher compression rate when compared to 320kbps MP3? If the algorithm is so good that it can compress audio down to 6kbps with just a few artifacts, would it sound almost good at 12kbps? 24kbps? Between this effort and the recently announced Google-led multi-channel/immersive audio codec initiative, I am pretty excited about the future of audio streaming and distribution.
  - brokenmachine 4y ago
    >recently announced Google-led multi-channel/immersive audio codec initiative Link?
  - beardyw 4y ago
    > they used specifically a 64kbps example, not a higher bitrate that would be more appropriate for music listening. ... but only if you are a bat.
    - genewitch 4y ago
      Bitrate as it pertains to the size is the purpose of all of this.
- bongobingo1 4y ago
  > not something I would want to use for music listening The flute in particular suffers quite a lot and the triangle disappears completely!
- Workaccount2 4y ago
  It is something you would want though if you are hosting content with audio consumed by people who aren't paying attention to audio quality.
Dwedit 4y ago
Because writeups are done at the last second, rather than as part of the project.

bscphil 4y ago

> While such techniques have been explored before for speech, we are the first to make it work for 48 kHz sampled stereo audio (i.e., CD quality), which is the standard for music distribution. Reading this extremely charitably, I think the contrast is supposed to be to speech which is normally uses much smaller sample rates. E.g. AMR-WB samples at 16 kHz. Speex, back in the day, supported up to 32 kHz. Full quality digitally distributed audio is often sampled at 48 kHz (e.g. Opus - the default audio codec on YouTube and many other sources), so I think "CD quality" is just supposed to emphasize that it's full-band rather than wide band or narrow band.

earthnail 4y ago

Since there is no perceptual difference to humans between 44.1 and 48 kHz, the statement about CD quality is perfectly fine - even more so as they operate on the higher sample rate. Most research in that field operates at 16kHz. Enough for most speech applications, not enough for CD quality. In general, CD quality in this field means a high enough sample rate that you can play all audible frequencies.

rzzzt 4y ago
They didn't specify bit depth either. I understand all of this reads like pointless pedantry, but a) it feels good indulging in it b) certain word combinations (such as "CD quality") have meanings backed by broad consensus, please use them responsibly so readers do not have to overexert their loose interpretation muscle. If they mean wide band, say wide band, noone will bat an eye.
ihatepython 4y ago
No, CD quality means 44.1 kHz 16-bit. DVD quality would be 48 kHz. Higher sample rate does not necessary mean higher quality