The aliasing thread

[Majken]

You may check the .rar waves at the website to have a listening reference too.

Yer.. well I'm never gonna listen to those samples again. Last time I tried i started crying. It was the worst kind of torture I could possibly imagine. I'm oversensitive to high treble and i happen to be able to hear all the way up to 18kHz or so. It hurt like friggin crazy, especially through my sennheiser headphones that are sort of sharp sounding. Heh!

WilliamK: You're very right. However I tend to pitch samples like crazy heh. So to me it's sort of interesting. But then again I'm working on a synth atm where I'm trying to get high aliasing for a nastier sound. Ah well, it's fun stuff to look at anywho.

/Majken

[george]

Anyway, let the battle beging. People will see with time that aliasing is only a problem when you are really pushing the sound from its original root-key.

I don't see any battle really.

Aliasing is only one of many features who compromises a sampler. Kontakt or Match5 don't deliver great resampling sound quality but the rest of the features still make them good products.

I think it's interesting to know how much muddy or clean will a mix sound due aliasing, which is a matter of personal taste as well

I'm working on a synth atm where I'm trying to get high aliasing for a nastier sound. Ah well, it's fun stuff to look at anywho

What about using Tracktion sampler instead? For uber nasty sound I'd recommend Jeskola XS-1 because their distortion and bit degrader are really sick

[Urs]

You only need a 15khz sinewave sample as root (C-4) and proceed to play from C-4 to B-4 and B-3 to C-3 (backwards) at 80 bpm.

As you use a sine wave and the spectrums posted on that site show multiple frequencies, the phenomenon proved is not aliasing. Period.

Regards,

Urs

[Majken]

So what is it then?.. "Audio Mud" (caused by pitching), heh

/Majken

[WilliamK]

..

[Urs]

So what is it then?.. "Audio Mud" (caused by pitching), heh

/Majken

Maybe some samplers are a bit more advanced than others and feature an internal representation that we do not know about, or which might be based on spectrums at a certain base frequency. Then, a sine at any frequency might for instance lay inbetween the bins, and so it pours over the whole spectrum, or, in granular devices might be split into small pieces, whereas in simple sample players they do not.

Simple samplers might do better with sines, complex samplers might do better with music, dunno

However, the spectrums on that site do not say anything about aliasing. An aliased sine always remains a sine and will always do so.

Cheers,

Urs

[WilliamK]

..

[Majken]

However, the spectrums on that site do not say anything about aliasing. An aliased sine always remains a sine and will always do so.

Isn't the thing with aliasing that a sine will no longer be a sine? It will be a jagged sine, aliasing = overtones that did not originally belong to the material. Which is an artifact from pitching. At least that's what I always thought.

/Majken

[Robert Randolph]

Sorry, i was making music...


what's this all about again?



*snicker*

[Urs]

Funny, those short vertical smears at the beginning and end of a note obviously represent the samplers' technology to avoid clicks (which you even get when you start a sine at zero crossing). The EXS for instance doesn't click when playing back a sine (I would give a lot to know how they did that). This is a good thing for the musician, but on that site it appears as a pseudo-scientific disadvantage.

If you ask me, this site is a reality distortion field that is made up to confuse musicians for some (economic?) purpose

It would have helped more (the musician, not the author) to post a couple wav files with actually authentic musical material played back by different samplers. This gives musicians a better idea than suggestive assumptions that can easily be falsified.

Urs

[WilliamK]

..

[Urs]

However, the spectrums on that site do not say anything about aliasing. An aliased sine always remains a sine and will always do so.

Isn't the thing with aliasing that a sine will no longer be a sine? It will be a jagged sine, aliasing = overtones that did not originally belong to the material. Which is an artifact from pitching. At least that's what I always thought.

/Majken

No, an aliased sine remains a sine. No jags.

http://www.musicdsp.org/phpWiki/index.p ... liasing%3F

"Jags", whatever that would be, can only come from processes, such as distortion, granular stuff etc.

Cheers,

Urs

[Majken]

The BOTTOM image is a 15khz sine waveform done with a 192.000hz samplerate. Notice that it is "almost" smooth.

Well here's where good old Nyquist comes into play. A digital signal does not sound like it looks. 44.1kHz samplerate can play a perfect sine at 20kHz, meaning it can most definately play one at 15kHz. However looking at the the samples isn't gonna say much about how it sounds. When it's filtered and played back through the DA converter we're gonna hear it like a perfect sine.

The tests may not accurately show the difference between the quality of the playback and pitch engines in the sampler. But I believe that it does show there at least is a difference.

Just like you said though, more samples pitched up and down and compared would be interesting.

/Majken

[Urs]

Actually, if I just pump the envelope attack and release a small bit, it doesn't click.

Yeah, but I also want some punch... Attacks of 6+ ms (which makes sines un-clicky across the musical spectrum) are not acceptable if you simulate analog filter clicks... hence I think there must be some magic around that I havn't uncovered, yet...

If you ask me, you are totally right, and I would REMOVE both sites. Unless they change how they test the programs.

Thanks, yeah.

I generally dislike when developers attack other developers. We're such a great community. All developers I know in person are very nice people (and it's big fun to hang out for lots of beer even if we are direct competitors). If any dev thinks he's gotta rant about others publicly, the public (i.e. the KvR community) should give the answer.

Cheers,

Urs

[Majken]

"Aliasing is a term, most commonly used for the artifacts, specific to the digital audio world. Resampling, imperfect interpolation or distortion - they all will result in a high frequency buzz and non-harmonic frequency content."

A sinewave with high frequency buzz will look like a jagged/uneven sinewave. Since the buzz/distortion could be broken down to sinewaves at higher frequencies.

Meaning that if you have a perfect sinewave and connect an oscilloscope to the audio output it will be shown as a sinewave. If you pitch it until aliasing occurs it will no longer be a pure sinewave because of higher frequency content making it an uneven sinewave.

/Majken