In the Stanley Cup streams we’ve been watching, there are alternating faint tones in the background of all the game audio. They sound like “modem noises” and step discretely through a set of tones at a rate of about 2Hz.
I’ve been hearing them for several weeks now, and googling around it looks like other people are complaining too.
I did a little investigation and I can see them in the audio. See the horizontal lines at the bottom of this image? It’s divided into three of the distinct “notes” from the noise.
The most complaints about it are on Sportsnet, across all sports. Interestingly it’s not there for any commercials: just the sport itself. It gets louder in proportion to the overall loudness of the stream but it’s the same basic pattern in all cases.
Okay, I might be going insane, but even at absolute full blast on every control I have, there is no audio on that youtube video. Doesn’t even show up on the EQ.
I can’t hear shit in the YouTube video, but audio watermarking does sound like a strong possibility. I know SSTV uses that audio range (though I doubt it’s SSTV). If you can isolate just the data sounds, try running it through something like FLDigi and see if it can make heads or tails of it?
If I were a betting man, I’d say five will get you ten it’s FSK-encoded data; it’s a cheap algorythm (both in terms of cost and computer power), and it’s robust against the kind of things that they’d want it to be robust against, like corruption and static.
8PSK seems to look the most like that spectrogram (the image here is a waterfall, so rotate 90 degrees clockwise mentally): 8PSK - Signal Identification Wiki
Agreed on that. I think I identified an initialization sequence that recurs periodically.
My signal isn’t the cleanest… I’m recording via OBS from a pirate stream of someone else’s stream via Sportsnet. I’m going to look for cleaner sources.
I can imagine an encoding pipeline being set up badly enough to cause this, and I can also imagine noise reduction being set extremely aggressively also causing it.
But the fact that I’ve since found a bunch of people who opened support tickets to Sportsnet and are getting the runaround… This could well be a poorly implemented watermark.
I submitted this thread and YouTube video to the crew behind the Twenty Thousand Hertz podcast, who are experts in the field of sound. Let’s hope my query produces results.
