Audio File Formats Explained in Simple Terms
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headphoensAlmost everyone is familiar with the most commonly used file formats – for music, mp3 and wmv, for video, avi and mpeg, and for images, jpeg and gif. Unfortunately, these common formats are not the only ones we run into on a daily basis. On any given day, we are likely to also see .flv on Youtube or .pdf while opening documents.

It seems as though there is an unending list of file formats that accomplish the same task – saving a bunch of data. What is the purpose of the existence of these seperate formats, and why do they extend the list of available formats to “Save As…“? Is there any real difference between which extension a particular file is saved as, as long as it’s appropriate for the media being saved? Why, why, why do they plague me with their endless resistance to conversion?

The list of questions could go on, pretty much for the length of this article, but I believe I should provide some answers, since the questions are probably what led you here in the first place. So here goes nothing – a guide to the inner workings of the common, but still unusual file formats.

Technical Jargon:

    File Format: a specific way to encode data that is to be saved as a file. Please note that the file format does no encoding on its own – the encoding is left up to the codecs.

    Codec: a program/algorithm that encodes/decodes data to convert a file between different formats. The popular media codecs are generally for shrinking file size. Laurence did a post on codecs last year.

    Lossy Codec: refers to a codec that sacrifices file quality for the sake of compression.

    Lossless Codec: does not destroy any data, regardless of whether or not the data is necessary for the file’s integrity.

    Metadata: information about the file that is stored within the file itself – for example, when a picture was taken and what type of camera it was taken with, or the artist of an audio track. Karl has done a post How To Remove MetaData From Photos (Windows) How To Remove MetaData From Photos (Windows) Read More on how to remove metadata from photos.

    Container: a file format that concerns itself more with how data is stored, and not necessarily coded.

    Bitrate: the number of bits processed per second. To put things into perspective, mp3’s generally have a bitrate of 128 kbit/s, while CD’s generally have bitrates of around 1.4 Mbit/s.

    VBR/CBR: the difference between variable bitrate and constant bit rate is just that – VBR uses a higher bitrate to encode (and thus, allocates more space to)  more complex parts of the audio file.

Audio File Formats Explained

Itunes Codecs

.aiff /.wav

.aiff /.wav – These are both uncompressed, lossless formats, which means it takes about 10MB to save a minute’s worth of music. aiff was developed for Apple’s OSX, and wav for PCs, although both formats are compatible with both operating systems.

Wav is the format preferred by PC wielding audiophiles; mac users generally rip CD’s into the aiff file format. There are codecs like FLAC and WavPack that will compress .aiff and .wav files, although the resulting file will still be huge compared to the ubiquitous mp3 format. Simple Help has a great tutorial about playing .flac files in iTunes here; it is for Mac OSX users only.


.aac – Apple’s default audio format, AAC is a lossy compression scheme that was developed to replace mp3, but never achieved the prominence that mp3 has with listeners. Some argue that AAC produces the same quality audio at 96 kbits/s as a mp3 does at 128 kbit/s, but with the recent developments in mp3 codecs (particularly LAME), mp3s have performed far better in listening tests against AAC than in previous years. Nevertheless, when it comes to a sound quality to file size ratio, AAC beats MP3.


.ogg – Vorbis, which is the name of Ogg’s audio format, is an open source lossy compression format that is favored by developers of free software for its patent-free nature. Despite its claims of being able to produce better sounding music at smaller file sizes, Vorbis is not widely used because of its slow encoding time and the lack of native support from popular music players such as iTunes and Winamp.

However, many video game makers and programmers have begun using Vorbis because it is open source, and thus does not demand licensing fees like mp3 and aac do. If you are interested in testing the sound quality of Vorbis yourself, try the aoTuV modification of Vorbis and install the XiphQT plugin for iTunes.

Conclusion :

If you’re willing to sacrifice the storage space, and have ears sensitive enough to tell the difference between a CD and a ripped track, go with .wav or .aiff. Otherwise, .aac and .mp3 encoded at bitrates above 256 kbit/s are indistinguishable from CDs for the average person.

Vorbis performs the best at low bitrates around 64 kbit/s, whereas the LAME encoder for MP3 performs better at higher bitrates. Regarding VBR and CBR, the general rule of thumb is that VBR will produce better sound quality at a lower file size than CBR can.

Ultimately, it is up to your own ear to determine which codec to use, and which format is best for you. Perhaps you’d like to perform your own listening test, to determine how picky your ear is. If so, try WinABX, which is a program that performs double blind listening tests. When you finally decide which format and bitrate is optimal for you, get yourself a codec pack, and convert your music with the multitude of audio converters that are out there.

Not to ignite a flame war, but which format/codec/bitrate do you use? Do you think AAC or Vorbis will ever gain the type of popularity that MP3 has right now? Leave your opinion in the comments, and stay tuned for Part 2: Video!

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  1. la
    April 22, 2017 at 9:05 am

    This article cleared my confusion about all these format and codec stuffs. Thank you so much.

  2. Chetan Sachdev
    July 30, 2009 at 3:32 pm

    I enjoyed reading this article. I would like to have an article on Camstudio settings related to compression and having a good quality video with less size. Is there any article available for Camstudio settings ?

    • Angelina
      August 2, 2009 at 2:02 am

      I poked around in the archives, and unfortunately, didn't find anything specific to camstudio settings. However, since Camstudio uses its own codec that (allegedly) produces better quality files at a smaller file size, you can probably just play with the settings and figure out what works for you (and it wouldn't be as complicated as, say, picking WHICH codec and which format to use).

  3. Joshua
    July 30, 2009 at 3:03 am

    But Winamp does support OGG natively :o Most good players support OGG.

  4. Jalley
    July 29, 2009 at 4:19 am

    I actively pursue FLAC files when searching for downloads. The files are large, yes, but with increasingly speedy broadband, the extra time is fairly negligible. Also, Monkey's Audio (.ape) is a standout lossless compression program similar to FLAC; it works nicely.

  5. Aarne
    July 28, 2009 at 8:15 pm

    .WMV is for video and .WMA for audio? Or am I confusing formats and file extensions?

    What about .PNG?

    Otherwise, Great info.

    • kaz
      July 29, 2009 at 12:14 am

      PNG... I take it you're a synesthete?

      • Angelina
        August 2, 2009 at 1:56 am

        LOL clever way to put it

        .PNG is an image file

        I actually got really confused, and then attempted to look up "PNG Audio" on Google =[

  6. James
    July 28, 2009 at 5:11 am

    Very good post demonstrating a good knowledge of the codecs and whats best for them. Just thought I would add I've written a guide about ripping Flac audio in Linux in a few easy steps. Flac guide I hope people find this useful.

  7. James
    July 28, 2009 at 4:51 am

    There's some errors in your explanations. For one, .wav is not the native format for audio CD's; Red Book is .

  8. freddy
    July 28, 2009 at 4:47 am

    WAV is not the "native format of audio CDs". That doesn't even make sense, actually.

    I suspect that you mean that audio CDs and WAV files both use little-endian data. That's OK (but not necessarily always true of WAV), but AIFF can contain big OR little endian data.

    Also, AIF/WAV are not uncompressed, lossless formats. In fact, they may contain compressed audio. They *can* be uncompressed, but it is not a requirement.

    Maybe if you prefaced the whole article with "In iTunes,", then maybe this article would be a lot more accurate.

    • kaz
      July 28, 2009 at 10:23 am

      Yes, the format is not the codec - but in the case of WAV and AIFF, use of a compressed codec is a rare exception; it hardly belongs in a overview "in simple terms." The same goes for CDs; the data on an audio CD is in the same encoding as nearly all WAVs. For purposes of sound quality and format conversion speeds, they are the same.

    • Angelina
      August 2, 2009 at 1:50 am

      AH i'm sorry >< I must have gotten confused. WAV and Redbook are both encoded in PCM format, and somewhere in the middle I probably mixed them up. AHH sorry for the [accidental] misinformation! Also regarding AIFF/WAV being able to hold compressed audio, yes, that is true, but I tried to focus on the most commonly used/seen formats, which for WAV, is entirely uncompressed. Thanks for your really good point about Red Book though!

  9. Ace Bandit Mcgee
    July 28, 2009 at 4:20 am

    WMV is the best for audio. Yep. Definitely.

    • Angelina
      August 2, 2009 at 2:07 am

      are you referring to WMA? WMV is windows media VIDEO

      unless you're being sarcastic and I've missed it entirely =|

      I'd say it definitely depends on the situation, and what the audio is being used for. If it's just for casual listening, and the listener is not a super audiophile, then sure, whatever floats your boat. However, if it's for archival purposes, or for production purposes, I wouldn't say WMA is the ideal format to go with.

  10. Ryan
    July 27, 2009 at 7:06 pm

    Nice overview here. I'm def. going to refer people to this when they have questions. If anyone wants a more detail about optimizing Lame MP3 encoding read this reference: LAME MP3 Encoding Tips and Command Line Examples

  11. chanklor
    July 27, 2009 at 4:01 pm

    does anyone knows the reason why some car's stereos can't play certain songs?
    i have like a hundred songs in a usb flash, i plug it in my car, and just like half of the songs songs are played, and when i try to play the other half, it just says ERROR. does anyone knows why? i've checked the songs' properties and they have the same BITRATE, the same CBR, the same everything...!!!! it's frustrating

    • kaz
      July 27, 2009 at 4:06 pm

      What format are they stored in? If they're in WMA or certain other formats and (likely if you bought them online) they may have DRM, which is not trivial to remove and would make it impossible to play them on a stereo.

      • chanklor
        July 27, 2009 at 4:28 pm

        mmm, they're stored in MP3 format. i downloaded them from rapidshare...

  12. Filipe Carvalho
    July 27, 2009 at 3:30 pm

    Winamp DOES support OGG in its default installation:

  13. kaz
    July 27, 2009 at 3:25 pm

    You missed lossless compressed formats, such as .flac. It has the same perfect quality as .wav and .aiff, but takes about half the space.

    • Angelina
      July 27, 2009 at 8:38 pm

      actually I think I mentioned them at the bottom of the paragraph about lossless formats, but only in passing. There's a link to .flac 's homepage, and a good article on making itunes play .flac encoded audio.


      • kaz
        July 27, 2009 at 8:41 pm

        Ah. I read too fast =P

  14. Will Mueller
    July 27, 2009 at 1:09 pm

    Glad someone finally did a post on this. I usually use WAV when ripping CDs, but, like you said, it takes up like 40-50mb for a 4-5 minute song, except you can get somewhere around 1000kb/s audio bitrate, which is exception, but usually not able to be played through the average soundcard. In any case, when ripping CDs from audio it is generally just good practice to use 320kb/s MP3 because it is high enough quality and is not too large of a file (around 10mb per 3.5 minute song).

    • Angelina
      August 2, 2009 at 2:11 am

      I've actually read a couple articles that said the average listener can't tell the difference between 256 kb/s and 320 kb/s, so I think for the average listener 256kb/s is probably enough. However, if you have the disk space to spare, then why not go with a higher bitrate, just to.. yknow, kick in the psychological "i'm listening to better quality files" mindset?

      or maybe I just find high bitrates unnecessary because I have a hard time telling between 128kb/s and 320kb/s LOL