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View Full Version : Audio Quality ACC vs CD experiment


audidrv
11-01-2004, 06:25 PM
So,

My 20 gig Ipod comes in this week. I Downloaded Itunes and started playing with it, researched formats and started to convert my cd collection to AAC at 192KBPS

Now i do care a great deal about audio quality, and i wanted the best sound from my ipod... however i am willing to make some compromises in the name of storing more music on this device... for any real lichening i will be using CD's ect on my home system.

so i figure aac @192 is a good size, and should be great quality.

I Used a set of studio monitors for this experiment. I hooked up an input selection switch to my monitors, a cd player on one end and my computer on the other. I got the two songs lined up dead even and switched back and forth between the compressed format and the CD.

I fully expected to not be able to hear the difference, however i was slightly disappointed that i could. Now this wasnt a big difference, but it sure was noticeable, digital artifacts and muddy midrange distortion through out the track, a lack of some midrange depth was also present.

I tried this with every track on the CD, some were worse the others. a few you could hardly tell (more acoustic tracks) but the more complex the recording the worse the artifacts and distortion got.

I started to play around with Itunes settings now and found the "Sound enhancer" slider bar in the audio preferences. to my surprise by setting this option ON and the bar to 50% the sound quality is improved vastly! Still not as good as the CD of course but it is so close now its hard for me to tell the difference.

My question now is, Itunes has the option, does the 4g ipod have this "sound enhancer" software switch as well?


Any who i though i would share my findings. nothing earth sharing here. All i have discovered for myself is that even a fairly high bit rate AAC file has noticeable artifacts and distortion. These are mostly solved with apples software however. I am sure that a bit rate of 256+ the difference between cd and AAC would be almost imposable to tell but for a compromise between quality and file size, I personally would not go lower then 192 in this format


-Charles

Breddy
11-02-2004, 09:17 AM
Did you try this same experiment with MP3?

-Breddy

Breddy
11-02-2004, 07:02 PM
Also, the experiment didn't factor out the DAC difference. If you are recognizing compression artifacts you're probably safe doing it the way you are, but for a true test of just the AAC compression algorithm, I think it would be more scientific to use the same hardware, i.e., compare AAC vs WAV using the same sound output device.

I'm not trying to kill your test here, I'm just fairly interested in the results :) I may have to set something up here but I really don't feel like moving around either my PC or my hi-fi gear!

-Breddy

CryingWolf
11-08-2004, 08:24 PM
Agreed about the DAC

What about lossless? vs wav vs ACC

I have had no issues with 192AAC . I think the size vs. quality is a good trade-off.