important iTunes install info

Z

zootbobbalu

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Dont freak out if iTunes hogs your CPU and your music starts to cut out unpredictably.

I just installed iTunes 3. After I changed some of the effects preferences, iTunes started to cut out from time to time when I would change applications or when I would open up web pages. This was really annoying.

After watching "top" from the terminal and observing how many CPU cycles iTunes was taking up, I noticed that iTunes was taking up 85% of my 450MHz G4!!!!!

Turns out that the "sound check" effects setting is the cause. This effect really taxes your CPU. If you don't have a Dual 1GHz G4 Tower and you need to get work done on your mac, you can stop iTunes from scanning your entire music library by clicking on the x to the right of the status bar.

If you have some time to kill, then let iTunes do its thing after adding the "sound check" effect. iTunes is taxing your CPU because it is scanning every song in your music library. I don't know how long this takes, but I have a large music library (40GB) and iTunes was still scannning after 15 minutes of waiting.
 
I encountered a weird problem where, upon launching VirtualPC and starting my Windows 2000 Pro installation, iTunes stopped playing completely. Actually, that's not exactly accurate. The volume just stopped. The song was still playing away -- I could tell by looking at the status bar in iTunes and see that the seconds were still counting away. Changing the volume up or down, even in the slightest, using the keyboard volume keys restored the sound.

This is completely repeatable with VirtualPC, and semi-repeatable with other processor-intensive applications.
 
Same here!

I wondered what was going on - I had indeed clicked 'check sound levels' so now all is explained.

I've only got a few hundred meg of mp3's so didn't take too long.
 
If anyone else is having this slowdown, can you let me know how long iTunes took to scan all of your music library (library size would be good to know too).
 
Are you sure that it's scanning every song in your playlist?

I thought all it would do is adjust the volume as the song is being played so that all the songs play at the same volume level.
 
I'm not sure, but why would iTunes need 85% of my CPU to adjust levels?

Other people have reported that iTunes stops hogging CPU cycles after running in "sound check" effects mode for a period of time.

If I have to except 85% CPU overhead just to listen to music in "sound check" effects mode I'm not going to use this effect.

I'm going to run iTunes while I sleep tonight and I'll post what happens.

Oh, to answer your question, I think iTunes is checking every song so it can create a record of the levels of every song, this way iTunes wont have to recheck songs over and over again.
 
like what zoot said, yes, iTunes is remembering the levels of each song and adjusting their playback volume accordingly. Of course this library also goes to the iPod. I wonder if it the library is song-specific, i.e. each MP3 gets a little tag added that says how much to change volume, or if it is just one big database stored somewhere on the comp? I would guess the 2nd option.

I think the better way to approach the Sound Check is to bring up a dialog box on 1st iTunes launch like previous ones that says "would you like to enable sound check? this will take some time to set up" or something like that.
 
I just tried out this sound check thing, and it appears that you are correct about it scanning all of your files.

It actually shows that it's doing it in the play window(where it shows the song title, time remaining, progress, etc), displaying the song that it's scanning.

However, you can stop it easily by clicking on the little X button that appears in the play window.

FYI, scanning 166 songs took less than 2 mins on a G4 400.
 
I just ran iTunes in "sound check" mode to see how fast my 450MHz G4 Cube would scan my music files for sound levels, and the time it took to scan 100 songs was 1 minute and 20 seconds. At this rate it would take about 30 minutes to scan the rest of my collection. That's not too bad. I just wish I would have known from the start what was causing iTunes to cut out in the first place!! I went crazy thinking I would have to uninstall iTunes and find a copy of iTunes 2 because Apple took iTunes 2 off of their web site, then when I figured out that it was iTunes scanning every song I thought it would take forever. I guess I should just chill out and enjoy the music :)

Recap:

it took 80 seconds to scan 100 mp3's (192 kbps each) on a 450MHz G4 Cube
 
like what zoot said, yes, iTunes is remembering the levels of each song and adjusting their playback volume accordingly. Of course this library also goes to the iPod. I wonder if it the library is song-specific, i.e. each MP3 gets a little tag added that says how much to change volume, or if it is just one big database stored somewhere on the comp? I would guess the 2nd option.

I think the better way to approach the Sound Check is to bring up a dialog box on 1st iTunes launch like previous ones that says "would you like to enable sound check? this will take some time to set up" or something like that.
Click to expand...

Erm... Did I say that? :confused:
 
Originally posted by xoot


Erm... Did I say that? :confused:
Click to expand...

nope, sorry xoot, I meant zootbobbalu a few posts up. But Z and X are right next to each other on the keyboard so it couldhave been possible...unless of course you use the wonderful Dvorak layout :)

and JetOSX, what do you mean they are requiring USB? (i'm not using my mac now so can' t try iTunes...not fair :p!)
 
Am I the only one that has noticed that the sound check thing is useless? It would have been great to equalize the volume of my MP3s. What it seems to to is flatten the volume level within the track. Additionally, any track that resembles having a wide dynamic range gets distorted.

~30 minutes of choppy sound whilst it scans all the tracks.
~7 minutes of listening to flat distorted sound.
~ 6 seconds to turn it off in disgust.
 
I'm assuming the "sound check" option works similar to technology that radio stations use to ensure that the songs they play are all at a similar volume level -- you know what I'm talking about. Throw in one of your CDs at home and listen to it... then throw in another, and it plays slightly louder or softer... sometimes more or less than slightly. Radio stations use a "volume equalization" thing to make sure that the stuff they play on the radio plays at the same volume so they don't blast your radio when they throw on a song that's louder than others...

You'll notice on the radio that it DOES mess with the fidelity and sound of a song, too. For example, some songs start softly and gradually fade into the main part of the song -- on the radio, you'll hear more static during the fade-in because their computers are "equalizing" the volume... they're raising the volume to their preset setting, thinking the song is playing too softly. Then, when the song really gets into it, the volume will back off a little bit -- so the song, regardless of the softness/loudness changes in it, plays at relatively the same volume. The result is a more flat sound with less dynamic range. I'm pretty sure the technology iTunes 3 is using to accomplish this is very similar.
 
The process 'ElDiabloConCaca' is describing is called "compression", where the volume dynamics of a particular audio source are suppressed, and the peak volume is then typically raised to the point where the volume peaks used to be. iTunes, however, is only normalizing the audio files. I don't believe they make any changes in dynamics, though the 'audio enhancer' feature does definitely play around with stereo effects. Normalizing simply changes the overall volume of the file based on a predetermined standard.... so this way all of your songs will have the same peak volume. Real-time compression would be too CPU intensive to make it worthwhile, plus many people would be unsatisfied with the changes it makes to the song. Artists and producers engineer a mix the way it sounds good, and beyond basic equalizing and spatial effects, it shouldn't be messed with. I haven't had a problem playing back any songs yet, but I haven't listened with anything other than my iBook speakers... :D If Apple did include the compression on this release of iTunes, that's pretty stupid. I agree with 'DazedAndConfuse' that it would definitely suck

Matt
 
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