Apple Lossless Conversions to Lower BitRates

2nd Part of Useful Suggestions:

This was originally posted by the incredible Sparky the wUnderdog with help from MacMuse:

As a general principle, you can fit more CD's on your iPod if you encode at lower bitrates (making smaller files), but at the cost of audio quality. Apple Lossless promises to capture all the data on the original CD (thus preserving quality) but coded so the file takes half the space. MP3 and AAC (an implementation of variable bit rate MP4) both eliminate some of the information on the CD in order to compress the digital recording into ever smaller files--the lower the bitrate, the smaller the file, but smaller files mean more information lost and consequent poorer sound quality.

AAC files ripped in iTunes certainly sound better than its MP3's, with audio quality close to the best LAME MP3's at higher bitrates. With the type of music I listen to most often, sound quality declines substantially as bitrates fall below 256kbps, but LAME or AAC @ 256kbps sounds pretty darned good, and at 320kbps LAME alt-preset-insane is amazingly faithful to the original. However, many users claim that with the music they listen to they can't hear the difference between 192 or even 128 kbps files and the original CD source, so they naturally choose lower bitrates to fit more "songs" on their iPods.

CDs take approximately 10MB per minute of music; Apple Lossless takes 5MB/minute; LAME insane takes 2.5MB/min; AAC or MP3 at 256kbps take 2MB/min; and iTunes Store files (AAC@128kbps) take 1MB/min. At these rates, a 20GB iPod (really 18.6GB) can hold anywhere from 30 hours to over 300 hours of music. (iPod marketers express this potential playback capacity as "songs," figuring 4 minutes per song--thus 300 hours at 128kbps = 4500 "songs.") You will need to listen to samples ripped with different bitrates and codecs to determine the optimum tradeoff point for you between quality and quantity. It's worth taking some time to do this at the start as it sure beats reripping everything in your collection 2 or 3 times to get it right later.

So far as convenience goes, nothing beats iTunes's one-step process. To change bitrate as you import from CD, go to the iTunes menu>Preferences, select the Importing tab, choose AAC or MP3 encoder in the "import using" selection box, then choose "Custom" in the "setting" box, and the window permitting bitrate selection will pop up. If you choose iTunes MP3 encoder, at least use VBR (variable bit rate) to maximize the sound quality. (VBR increases sample size as data complexity increases.)

If you would prefer LAME MP3's, fear not, for the easy-to-use CDex ripping software is a free download and requires only one simple extra step to get the files into iTunes for transfer to your iPod. Now if AAC sound quality is comparable to LAME MP3, you might wonder why you should even consider LAME: Because of portability to other devices. At present, hardly anything but iPods can read AAC's or Apple Lossless, but almost everything reads MP3's. So if you plan to burn CD's of your compressed files for playback on your home or car CD player (for instance), it would be wise to choose MP3.

One other consideration specific to the iPod- It has a 32MB cache (If you don't know what a cache is, read the last paragraph of this page: iPod + iPod Mini- Batteries). Keep individual file sizes below 25 MB as the rest of the 32 MB memory holds the iPod's Operating System. If you choose a compression rate that results in large files (ie.. Lossless), then the cache won't hold very much 'music' and the hard drive will have to spin up frequently to fill it, and that will shorten your battery life somewhat.

Edited by The Mimico Kid

3rd discussion by StarDeb 55:

Message #1.1.1.2.1.1.1.1: RE: Features I'd like to see added to iTunes
Posted by StarDeb55 on 11:15pm Sep 13, 2005 CDT

Zentor, when I did the previously mentioned test I also imported in Lossless. I can't tell a lie the audio quality was outstanding compared to even a high bitrate AAC. It's possible to import in Lossless then "downsize" to sync to iPod. One way this could be done is to change your importing format to the lossy format you want to use, then right click on the Lossless songs & click "convert to AAC."
You would not suffer an audio quality loss since you are going from Lossless>Lossy. I have adequate room to do this as my library is stored on a 180GB EHD, but my problem is I don't have adequate time. I also don't want to have to separate the duplicates which will occur when you make the conversion. If you want more infomation on going from Lossless>Lossy due a search in the forums for Buegie, one of our regular posters, who I'm pretty sure is in the process of actually doing this.

When it comes to the VBR option, you are not limited to 128, you can set the bitrate where you want. I did some "Google" searches over the weekend to improve my understanding of the VBR option, & I would suggest you do the same. My basic understanding of how it works is that, for example, you are set to import AAC @256 with VBR, during quiet or less complicated portions of a song the VBR would decrease the bitrate because there are less things that have to be detected in th! e file, during more complicated, difficult, louder portions of the song, the VBR may increase the bitrate >256 to insure that all important audio dynamics of the song are recorded. Long story, short, the 256 would end up being an average. Here's a link I posted over the weekend that provides a little more information.

StarDeb55, "AAC VBR encoding" #5, 05:04pm Sep 13, 2005 CDT

3rd part of discussions in another thread

Helicon Twist 2008
Joined: Aug, 2005
Posts: 16
Earth Thank you both for your responses.

What I'm trying to do (the short version) is to first archive my CDs in Apple Lossless format, then have them converted to AAC format (at a sampling rate of my choosing) for transfer to an iPod.

I assumed that I needed to separate iTunes libraries to do this. The first would have all of my music in Apple Lossless format. Into the second, I would import everything from the first into AAC format.

But based on your responses, it seems that I start with a single iTunes library and import the CDs to it as Apple Lossless. The resulting music files get put in a smart playlist set up to capture only Lossless files. I then create new smart playlists set up to capture anything that isn't a Lossless file. With a right- (control- ) click, I can convert the Lossless files to AAC format, the songs from which go to the correct playlists. Finally, I set up iTunes to transfer only the AAC playlists to my iPod.

There's a problem with this method, though: won't my iTunes library now contain a Lossless and an AAC file for each song? And doesn't iTunes transfer the entire library of songs to the iPod, regardless of playlist?

Please clarify so that I can confidently embark on my CD archiving project... and, thanks again!

__________ANSWER____________

Michael Allbritton
Level 3
Joined: Dec, 2000
Posts: 1035
Directly Above the Center of the Earth! When you transcode the Lossless files to AAC, yes, you will have two copies of the same files in your Library. But you don't always have to keep the AAC files around. For example, I have all my live music in Apple Lossless, and when I want to take some on the iPod I use another Automator Workflow I created to transcode it and copy it to a Playlist that syncs to my iPod. When I'm done with the AAC files I delete them.

Which brings me to your question about syncing to the iPod. You can set up a Smart Playlist that, depending on the criteria you use, will contain only music you want to have on the iPod and tell iTunes to sync only that Playlist to the iPod. For example, the criteria might be:
"Kind is aac audio file" (This will exclude any Lossless files from the Playlist.)
"Limit to 15 GB selected by random" (This will limit the size of the playlist to 15 GB and select songs at random from your Library of AAC file.).

There are a wide variety of criteria to use, and you should experiment to get the Smart Playlist to behave just how you want it to. As long as you tell iTunes to only sync this Playlist to the iPod you won't go wrong. Or you can tell iTunes to manually manage the iPod which means you can then drag and drop only the music you want to be on the iPod.

You don't have to keep the iTunes Music folder at the root of the HD. But if you want other users on the computer to be able to have access to the music this is the easiest way to do it. There are no permissions to worry about, nor to you have to worry about music files being in several different user directories. It is all in one place. And about once a week each user can use the Add To Library command and add the files to their iTunes Library that they don't have yet.

If you have not found it yet you will find the iTunes Support page helpful.

Does that help?

Zentor
Level 2
I'm also trying to understand the complexities but it sounds like that everything
has to go into the library and use smart playlists/folders to manage files with
different bit rates. I've taken the liberty of your discussion and response and
transferred them over to another topic where I hope users can go and get
an overview more easily.

RESPONSE

Michael Allbritton
Level 3

Yes, all tracks go into the main Library. Using Playlists is not the only way to keep track of different bit rates and such, but for me it is the best way. You can also sort the Library by bit rate by adding that column to the display window. Pull down Edit > View Options (Command+j on the keyboard) and select the Bit Rate check box, then click the column to sort the Library. Personally, I don't like doing this; I find using a playlist to gather all the Lossless files into one location to work better.

Smart Playlists can be very powerful tools for working with your music if the Library starts getting large. I have almost 6500 tracks in my Library and I use a couple dozen Smart Playlists on a regular basis to let me find just what I want to listen to very quickly. If I get tired of listening to Party Shuffle, like I'm doing right now, then I can jump right to a particular Genre, Artist, mix Playlist in seconds.

Michael,
I will most likely do what you have done.
Now I know its easy to convert Apple Lossless to AAC by selecting
Advanced>Convert Selection to AAC which I will be using probably completely,
but just out of interest what is the process if its :

1. AAC higher>lower bit rate (do you just change the preferences in importing
and then use the same "Convert Selection to AAC") or is there another
process?
2. What about AAC>mp3 (or other)??

Thanks

RESPONSE>>>>>>>

Michael Allbritton
Level 3

The answer is, simply, yes. Just change the import settings in the prefs. However it should be pointed out that it is not recommended to transcode from one lossy codec to another. Like taking AAC 192 to AAC 128, or MP3. You will lose quality in the audio, and it may not sound good.

Say you have a some audio files you imported at MP3 320, and now you want to lower the bit rate on those files to fit more of them on your digital music player. Most people on these boards will recommend that you just import them again from the original CD, if you still have it. This will ensure you get the best quality sound in the lower bit rate file.

If you think you are going to be doing a lot of transcoding of Lossless to AAC or MP3 files you might find these Automator Workflows I've made useful. There are README files included with each archive that tells you what you need to know to use the Workflows.

Hi Buegie -- thanks for your great response which I hope will give a lot
of users in this topic the info they need.

I was sort of 20% through importing at AAC/128 -- my only benchmark were
my computer speakers and I couldn't tell much difference BUT after reading a
lot of the discussions, I became convinced that I better play it safe then sorry
since I plan to get a decent stereo system soon.

What I am doing is using one smart playlist as my NEW LIBRARY and then use
others to categorize and divide the different types of music. Hope it will work out.

Couple of questions I have for you if you don't mind:

Have you had any experience or seen comments re streaming Lossless music files to your
stereo through airport--is there any degradation or is it worth doing?

Smart Playlist:
I've set the number of songs at 0 and unchecked the box--will that give me
unlimited number of songs in this playlist or will there be a restriction?

How do I clean up my GENRE drop-down menu -- I know how to add categories through the custom option BUT how do I get rid of a lot of the ones I will never use?

Thanks again for your reply and I'll have a look at your link tomorrow.

Cheers,

Z.

Thanks Buegie for your reassuring reply. I'll be importing CDs until Christmas
(kidding I hope) but in the end I think I won't have any regrets. Take care and
Good Night!!!

just to let users know that have been following the discussion that to re-import
the songs using Apple Lossless is easier than I expected -- iTunes will ask
you if you want to replace the existing songs (at the lower rates) so you totally
avoid duplicate songs

As well it remembers which tracks you wanted to download so you don't have to go through the names again and set the importing on "automatic pilot"

Buegie
You're absolutely right--I had been hesitating because I'm re-importing about
3,000 songs so I wasn't looking forward to scanning through each CD again to
see which tracks were worth importing. Now I can basically do it while I'm
reading the paper.

Cheers