Hi there!

Listen to dithering algorithms used out there, "The Great Dither Shootout", link
In this thread there are some samples containing (amplified) noise shaped dither = loud high pitched noise. I tried to compress them to mp3 (lame aps etc.) and the result was awful ... chirping/ringing. Now there's another thread with a similar sample:
Test your soundcard for clipping, with this sample
This time, besides audible dialing tones, the sample contains a loud modulated 20kHz tone. If played back on not-so-decent equipment (I guess >90% of soundcards out there) without tricks (like software resampling) strange distortion is caused.

So I thought a combination of both could be used as some kind of CD copy protection. It'd work like this:

1. Add loud highpassed/ath shaped noise to the signal
That's it ... only one step!

Result:
1. Without special knowledge (resampling ...) PC playback won't be a nice experience while on decent hifi equipment it will sound OK.
2. Encoding to mp3 will result in artifacts, mainly chirping/ringing, even with --alt-preset standard (and higher).
3. Listening to these unchanged mp3s with cheap soundcard + no software resampling will be even more annoying ...
4. Lossless compression ratio will become worse.
[sarcasm]
5. Lots of fried tweeters, so hifi industry will be able to sell new stuff to ppl
[/sarcasm]

Some examples (in attatched .zip file)
india.flac - Original: 20 seconds of "India.Arie - Back to the Middle"
india_noise.flac - Original+noise
india_noise.mp3 - Original+noise, lame 3.90.2 --alt-preset standard -Z

Enjoy!

tigre

-edit: zip file attatched

Very interesting indeed.
Not that I like you giving bad ideas to the greedy RIAA...

Just one thing:
I was just reading the latest posts in the recommended compiles/settings thread (it even features something you wrote!) and it seems that HA admin is really trying to make people forget about the -Z thing and push for the adoption of 3.90.3 which already has it. This is to avoid confusion among board users (specially n00bs) and to unencourage the "experimenting" with switches which would lead to more confusion and degradation of quality (you wrote something like that!)
So let's try and not mention -Z, again!

It won't do anything against ripping/burning (anything lossless) of course.

Wouldn't it be just as simple as applying a lowpass (maybe @19.5KHz) ?

And some (not many) people might hear the added noise (as it would be loud). Also, could it bother radio stations, or do they lowpass @15 KHz?
--
Ge Someone

Right. I thought the big enemy of RIAA & co is file sharing, prevention of security copy for private use is just "collateral damage", isn't it?


You mean for getting rid of the "protection"? Yes, but as you'll find out if you listen to the examples (see 1st post), e.g. lame --aps's integrated lowpass doesn't help much to prevent artifacts / clipping on playback here ... It can't prevent anything, but it'll make things more complicated for Joe Kazaa.

There were discussions about it some time ago, when the first CD protections appeared. It seems it has already been done, and tested in central Europe CD production (unsure information), but given up quickly.

I see. Thanks for the info. Would have been too easy ...

Wait... they might have given up because of fried devices, not because of unefficiency.

I feel VERY uncomfortable with ultrasonic waves (above 16kHz) I can't hear above ~17400Hz but I feel it and my head starts to feel woozy, and I have to take a couple of minutes of rest to recuperate. So I won't buy those CD's and I can imagine there are at least a couple others like me.

i'm kinda glad that protection method was ditched... i just listened to "udial.ape" and was flattened by it (never thought i could hear that high).

but this would be a cool thing to put in movie soundtracks... like when somebody gets stabbed or something gross happens...

If you're human and your soundcard doesn't resample or clip, you shouldn't hear the high-pitched sounds.

I know this is an old thread, so it might be worth asking again now: has anyone every seen or heard (or heard of) a CD (or LP?) that makes use of this idea?

Cheers,
David.

Too late!

I just stumbled on this... SunnComm buys music anti piracy company

No more analogue hole.

Imagine to be forced to have to buy (again) the songs you have on CD to transfer them to a portable media since it would be impossible for you to rip it any way you'll try. (Or use the crappy versions in double on these CDs)

The question is, will the RIAA succeed in blewing up our fair use rights, and also prevent us from recording radio on tapes like it can be done with video by Macrovision.

The RIAA dreamt it, someone dit it.

okay... if this makes it into the market we can see a lot of expensive audio equipment becoming useless.

and a lot of fried tweeters, traumatised pets and confused bats.

[edit]

btw, we can still record this stuff on audio casettes so long as there's no auto-leveling. same with macrovision and VCRs with different AGC circuits to the ones assumed by macrovision to be universal (like my old toploader). it would mean the tape recording unnecessarily hot though.



well, i'm human, my sound card doesn't resample or clip (but it's got a VERY high noise floor unfortunately) and i heard it. Koss R-80 headphones and windows mixer on 2/3 full volume. no damaged equipment thank god.

This is not sure. I once came across a sample with high pitched noise, that was quite impossible to record on tape.
It was Cosmic Baby - Heaven's tears (Remix by Jam el Mar), the first 20 seconds. I'm at work and can't upload it now.

I've read about these. I'd reckon that they're a terrible idea, maybe the only time that a compressed file sounds better than the original