4/30/10
9:53 am

MacMost Now 392: Understanding iTunes Audio Formats

iTunes lets you use a variety of file formats for ripping CDs or converting music. Learn about each one: AIFF, WAV, MP3, AAC and Apple Lossless. Decide which format might work best for your music collection.

Video Transcript
Hi, this is Gary with MacMost Now. On today's episode, let's look at different audio formats used by iTunes. Now if you use iTunes to manage your music collection, you may want to know more about the different audio file formats that iTunes uses. So in iTunes, you have the choice between 5 different audio formats. And these are used when importing a CD or converting music from one format to the other. These are the formats you can convert to. But it may be useful to talk about a format that's not listed there. It's a format called Redbook. And the Redbook format is used by CD's, audio CD's and it's kind of been the standard for music since about 1980. Now, Redbook uses something called Linear PCM, which is a particular method of pulse code modulation which represents an audio waveform as a sequence of amplitude values recorded at a sequence of times. So it kind of looks like this if you take a look at it as a visual representation and you're probably familiar with as an audio waveform. And this is what's used on CD's and it's basically where you start if you're importing music from CD. So Mac starting handling audio early, 1988, Apple came out with the Audio Interchange File Format or AIFF. And this is very similar to Redbook. It uses linear PCM to represent an audio waveform as a file. So it's relatively lost its conversion from your CD's to AIFF format even though technically, it's not exactly the same format. And the file format itself isn't compressed at all so all the audio is laid out and is relatively large. Could be approximately 10 megabytes per minute of music. And the format used today as AIFF is a site variation on the original format but it's essentially the same. So in 1991, Microsoft and IBM came up with their own video format called the WAV format. Wave Audio Video format abbreviated WAV. And today, both Macs and Windows computers can play AIFF and WAV files so it really doesn't matter which format they're in. They're both lossless file formats that are not compressed. Now in the '90's, people got interested in compressing audio video formats so it'd be more reasonable to send them over the early internet. And the MPEG 1 Audio Layer 3 format, otherwise known as MP3 was born and this allows you to compress audio into a fraction of the size of the AIFF or WAV files and make it easy to send over the internet. Now you sacrifice some quality but you gain portability. So with the MP3 format, we had the beginnings of the music industry moving to the internet as people were exchanging MP3 files all over the place, legitimately and illegally. And this led to all the online music stores that we have today. But before that happened, these new file formats had taken over from MP3. So in 1997, a standard was released, the AAC Standard, which was developed by Apple and a whole bunch of other companies. And this has slightly better compression and better quality than MP3, it stand for Advanced Audio Coding and it's used now as the default in iTunes and in fact, it's also used as the default in a ton of other devices. But there's also the interest a lossless format, one that is actually not losing any quality but still compresses the music. And Apple came out with the Apple Lossless format and this format actually compresses the size of the files by about 50 percent but it doesn't lose any quality at all. So you can use Apple Lossless to record things in the same quality you would get with AIFF or WAV but save some file space. Apple Lossless is also very easy to decode, so low-power, small devices, like the iPod, can easily decode it and produce audio without using too much processor power and thus without using too much battery life. When choosing a file format to store your entire music library, you first want to look into if you want to put it into lossless format. Now AIFF and WAV have the advantage they've been around longer and thus they may play back on some devices that Apple Lossless does not. But Apple Lossless will save you a lot of file space. Now between MP3 and AAC, you have 2 good compression algorithms. AAC's better quality and better compression but there's some devices, for instance, a lot of car stereos that still don't support AAC. But AAC is being supported by more and more devices in just about anything new that comes out it's going to support that and it is the standard. So my advice is that in your extreme audio file, then you'll probably want to use Apple Lossless to store all your music and then convert it as needed to MP3 or AAC to put it on to various devices. AAC, if you're to put it on an iPod because Apple Lossless format will probably take up too much space for you to fit enough music onto your iPod or iPhone. Now for everyone else, probably storing your files in AAC format is the best idea unless you have a specific device, like let's say your car stereo that only supports MP3 files. In that case, you may want to use high quality MP3's instead. Hope you found this look at iTunes file formats useful. Till next time, this is Gary Rosenzweig with MacMost Now.

Comments: 6 Responses to “MacMost Now 392: Understanding iTunes Audio Formats”

    Adrian
    5/1/10 @ 11:16 am

    Gday,
    I have just found your site, and have to say you are so knowledgable.
    There is more to learn in listening to a few minutes of your words than I have found elsewhere, and in many you tube videos combined. Thankyou for taking the time to create such carefully prepared videos. It is much appreciated and look forward to going back through some of the previous ones made.

    Cheers,
    Adrian

    Paul Brainerd
    5/3/10 @ 6:03 pm

    I know this goes beyond the scope of what your webcast encompassed, but the evolution of Metadata ID3 is interesting, as well as the royalty and fees associated with compression formats like mp3. It really is amazing how many formats of video, music, and GUI’s is general, are born from the fact of circumventing patent rights.

    Brent
    5/4/10 @ 8:11 pm

    My brother put me on to your informative and accessible items – I appreciate them. There’s a catch; when my bro converted to Apple Land, he gave me his Windows system, so that’s where I live. As I listened to this item, I wondered where .flac figures in all of this and the degree of transfereability of the lossless methods you mention to Windowsland.
    Thanks

      5/4/10 @ 8:16 pm

      I never thought to check out the iTunes options on Windows. Are they not the same?

    Ralph
    5/8/10 @ 12:41 pm

    Gary
    A great summary of the audio format issues!
    It was most timely and helpful, as I am in the process of converting my entire CD collection to digital.
    Based on your comments on the pros and cons of each format, I have opted for Apple Lossless as the best way to create audio files which best compliment the audio capability of my home entertainment system.

Comments Closed.