4 ms·

I wonder how they are doing this. Wouldn't a low quality recording render this fingerprint invisible?

diebeforei485 6y ago
I'd love to see some analysis of what's going on as well. I assume this would work better for audio recorded on-device (eg. using screen capture software) than audio recorded externally after being played out on the speaker.
grenoire 6y ago
I wonder if it can be filtered out, on the other hand. Does anybody have knowledge on audio fingerprinting/watermarking? Or is it perhaps security theater?
- jcelerier 6y ago
  most common technique is a spectral encoding, which can be quite resistant to degradation. here's some old (ugly) code - quite short as you can see: - encoding: https://github.com/jcelerier/libaudiotool/blob/master/src/libwatermark/watermark/SSWEncode.h#L43 https://github.com/jcelerier/libaudiotool/blob/master/src/li... - decoding: https://github.com/jcelerier/libaudiotool/blob/master/src/libwatermark/watermark/SSWDecode.h#L46 https://github.com/jcelerier/libaudiotool/blob/master/src/li...
- banger180 6y ago
  My Guess is that it is mostly a security through obscurity thing for now, we do not know exactly how they mark the audio. When someone figures this out I believe that it should be possible to filter this out. It would be interesting if they found a way to watermark the audio in such a way that removing the mark makes the audio unusable.
  - slezyr 6y ago
    Just compare two records from two different users.
- eigenvector 6y ago
  If the watermark is inaudible, can't it removed by re-encoding the audio with a bandpass filter tuned for audible range?
  - ithkuil 6y ago
    Inaudible just means that a person can't perceive it, not necessarily because it's outside the frequency range a human ear can sense. A common technique is to add pseudo noise to encode data over the whole audio spectrum. It's related to the spread spectrum techniques used for radio communications resistant to signal degradation (natural or jamming), common in many radio protocols, like your GPS receiver in your phone. https://en.m.wikipedia.org/wiki/Audio_watermark https://en.m.wikipedia.org/wiki/Audio_watermark
- lozf 6y ago
  Streaming and downloaded audio from Universal Music Group, and some Sony releases has been "inaudibly watermarked" for some years now, but there are several cases of people complaining that the watermark is actually audible in their supposedly lossless FLAC/ALAC/WAV download. AFAIK these are just used to identify the streaming / download source (e.g. Spotify / TIDAL / Qobuz etc.), rather than the individual user as will be the case with Zoom. It'll be interesting to see what, if anything, has changed with the technology.

I'd love to see some analysis of what's going on as well. I assume this would work better for audio recorded on-device (eg. using screen capture software) than audio recorded externally after being played out on the speaker.

grenoire 6y ago

I wonder if it can be filtered out, on the other hand. Does anybody have knowledge on audio fingerprinting/watermarking? Or is it perhaps security theater?

jcelerier 6y ago
most common technique is a spectral encoding, which can be quite resistant to degradation. here's some old (ugly) code - quite short as you can see: - encoding: https://github.com/jcelerier/libaudiotool/blob/master/src/libwatermark/watermark/SSWEncode.h#L43 https://github.com/jcelerier/libaudiotool/blob/master/src/li... - decoding: https://github.com/jcelerier/libaudiotool/blob/master/src/libwatermark/watermark/SSWDecode.h#L46 https://github.com/jcelerier/libaudiotool/blob/master/src/li...
banger180 6y ago
My Guess is that it is mostly a security through obscurity thing for now, we do not know exactly how they mark the audio. When someone figures this out I believe that it should be possible to filter this out. It would be interesting if they found a way to watermark the audio in such a way that removing the mark makes the audio unusable.
- slezyr 6y ago
  Just compare two records from two different users.
eigenvector 6y ago
If the watermark is inaudible, can't it removed by re-encoding the audio with a bandpass filter tuned for audible range?
- ithkuil 6y ago
  Inaudible just means that a person can't perceive it, not necessarily because it's outside the frequency range a human ear can sense. A common technique is to add pseudo noise to encode data over the whole audio spectrum. It's related to the spread spectrum techniques used for radio communications resistant to signal degradation (natural or jamming), common in many radio protocols, like your GPS receiver in your phone. https://en.m.wikipedia.org/wiki/Audio_watermark https://en.m.wikipedia.org/wiki/Audio_watermark
lozf 6y ago
Streaming and downloaded audio from Universal Music Group, and some Sony releases has been "inaudibly watermarked" for some years now, but there are several cases of people complaining that the watermark is actually audible in their supposedly lossless FLAC/ALAC/WAV download. AFAIK these are just used to identify the streaming / download source (e.g. Spotify / TIDAL / Qobuz etc.), rather than the individual user as will be the case with Zoom. It'll be interesting to see what, if anything, has changed with the technology.