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From AAC, DSF and Flac to Mp3, Ogg Vorbis and WAV – Codecs

Intro

Contents

We stream a lot. Especially among you – the readers – streaming has become very common. We hardly ever think about what format we are streaming. AAC? ALAC? WAV? FLAC? We list these formats for you. Because one codec really isn’t the other!

You ‘rip’ a CD and suddenly get a load of complex quesetions on screen: how do you want to save the files? Without compression in .wav? Or do you want to go for lossless compression with ALAC or FLAC? Do you want to go as small as possible with “lossy” compression? Think AAC, MP3 or Ogg Vorbis? Choices, choices…

Codecs: two flavors

It is important to make a rough separation in the file formats. After all, there are formats – codecs: ‘enCOding / DECoding- that throw away data when making the file smaller (compressing) and formats that do not throw away data when reducing the size of the file. We call these formats Lossless (without loss of information) and Lossy (with loss of data).

Examples of lossy codecs are MP3, Ogg Vorbis and Opus. Examples of lossless formats are ALAC, FLAC and WMA lossless. WAV and AIFF are not included because they are uncompressed formats.

Tagging

An important feature of file formats – the files that use a particular codec – is the support for adding labels: tags. Software, by itself, is rather stupid. It does not recognize artists, songs or genres without help. Perhaps advanced AI add-ons will help, but for now it is not possible.

So we need to add labels to the files. With these labels we indicate who the artist is, what the name of the song is, on which album the song belongs, what the year of release is, et cetera.

Now, not all files support tagging and not all software can read all tags. For example, .WAV used to have a problem with tagging because .WAV was originally just an archive format. A file to make a direct copy of, say, a CD. Or just to make recordings. At the time, nobody stored albums in .WAV because it was way too big and storage space was way too expensive. So those few “idiots” who used WAV for copying CDs, they well… we’re out of luck. Although .WAV can now be tagged, it is not universally supported. FLAC, ALAC and (almost) all ‘lossy’ formats can be enriched with tags.

Support

Although this is not really a problem anymore, it is advisable to check whether certain formats can be played. FLAC is still not well supported on Apple-devices, for example. Ogg Vorbis is also not natively supported on Apple products. These formats can be played through VLC or perhaps Foobar. MP3, AAC, WAV are supported everywhere.

Bits and sampling rates

When a studio makes a recording of a band, it is usually done with 24 bits per sample. This gives dynamic freedom. The sampling rate – the amount of samples per second – can vary. Usually it is 44.1 kHz or a multiple of it: 88.2, 176.4 or sometimes even double that. 48 kHz and multiples thereof are also used, but are officially sampling rates for multimedia (movies / etc).

More and more music is released in ‘studio quality’ or: High Res. Sometimes this really sounds better, sometimes it doesn’t. It depends on how good the recording is. It depends a bit on how good the master is.

When storing music, you don’t want to lose any quality. You want to save lossless and then also preserve the bit depth and sampling rate. Fortunately, all lossless codecs support 24 and even 32 bit and high sampling rates. FLAC in particular is very flexible in this regard. Lossy codecs change bit depth to save space. Partly because of this, the noise floor fluctuates. This also causes unrest in the playback. However, most codecs can handle 24 bits and higher sampling rates.

Multichannel

For surround enthusiasts it is good to know that most lossless codecs – and some lossy variants – support multichannel audio. FLAC and ALAC, for example, support multi-channel audio. With mp3, an add-on is required. AAC supports surround by default (not surprising, this codec is widely used in video containers).

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