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AAC files with a Freq. cut off of 22.1

post #1 of 11
Thread Starter 

How is this possible? when i analize those 10mb files on the spectro they are full of sound and have a 22.1 cutoff freq how is this possible they look like any lossless file ..? someone could sell you a disc with those inside just converted to wav and you will never know.

 

Please explain? thanks

post #2 of 11

Because digital compression has come a long way and does a very good job? They maintain the same sample rate so the frequency response should go relatively unaffected. Your SNR will go down a bit but quality is by no means bad.

 

Try compressing a really dynamic file (with loud and soft sections) then sum the inverted compressed file with the original in audio editing software, the resulting track will be the difference in the files. It will consist of random noise that should resemble white noise. 

post #3 of 11
Thread Starter 
Quote:
Originally Posted by 65535 View Post

Because digital compression has come a long way and does a very good job? They maintain the same sample rate so the frequency response should go relatively unaffected. Your SNR will go down a bit but quality is by no means bad.

 

Try compressing a really dynamic file (with loud and soft sections) then sum the inverted compressed file with the original in audio editing software, the resulting track will be the difference in the files. It will consist of random noise that should resemble white noise. 

 

but lossless is still better right? and how to tell if someone sells you a fake CD with just those files inside?

post #4 of 11
Well of you're going to buy CDs only buy them sealed and unopened online or only after physically inspecting the disk to ensure its the original. Buying burned disks is very illegal and all around a bad idea. Lossless is just that. It's the original content at the full quality of Red Book if on a CD.
post #5 of 11
Thread Starter 
Quote:
Originally Posted by 65535 View Post

Well of you're going to buy CDs only buy them sealed and unopened online or only after physically inspecting the disk to ensure its the original. Buying burned disks is very illegal and all around a bad idea. Lossless is just that. It's the original content at the full quality of Red Book if on a CD.

 

okay thanks.

post #6 of 11

Pretty much nothing can play below 30hz so that doesn't matter

 

320AAC or MP3 is good only go to lossless if YOU can tell a difference.

post #7 of 11
Quote:
Originally Posted by ScaryFatKidGT View Post

Pretty much nothing can play below 30hz so that doesn't matter

320AAC or MP3 is good only go to lossless if YOU can tell a difference.

Any decent IEM should hit 20 Hz pretty easily; many will go lower.
post #8 of 11

Most people even with decent hearing can't hear 20Hz, it is the bottom threshold for GOOD hearing.

post #9 of 11

20Hz being the bottom threshold is an estimate for the most part. And everyone's hearing at that range is about the same, you don't lose low frequencies as you age like you do the high frequencies.

 

It can however still be perceived below that. Just not heard.

post #10 of 11
Quote:
Originally Posted by 65535 View Post

Most people even with decent hearing can't hear 20Hz, it is the bottom threshold for GOOD hearing.

I can hear down to 20 Hz (and a bit lower) without problem. Above 14 kHz is a different matter, since I'm old.
post #11 of 11

I know I hear down to 16-17Hz tested with for example XB500 and Q40. The upper limit I can't accurately tell as I've not had experienced with any good extentended highs in headphones yet, most headphones I've had drops significantly at least after 15kHz. When doing the FR sweep tests I tend to put volume very low as I hate those loud sine frequencies and I never turn up the volume more either compared to what's comfortably listenable at say 1 - 10kHz so therefore it relies quite a bit on the highs extension for the headphone to give me an idea of my upper-end hearing.


Edited by RPGWiZaRD - 1/30/13 at 5:38am
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