This article is meant for the ones who decided to “experience the digital world” and want to store all their CD library into the Hard Disk. Of course there’s not a single way to do it, so the hope of this article is giving you an help doing the right thing in the right way, avoiding to waste a lot of time.
Choosing the right compression format
Choosing the right compression format is actually a lifestyle philosophy more than just a choice. There are tons of so called audio compressor that allows to store the data in several ways… so just let me employ my little knowledge to shade a bit of light on this argument .
WAV (uncompressed audio) format is definitely the rawest and quality-proof way to store music tracks. It does not imply any form of compression, it just stores ordered sequence of bits as they arrive from the source. Choosing WAV as a storage for your album, as far as this introduction could ever suggest, is, in my opinion, the worst way to build up your album collection. WAV format requires a large amount of space (about 500-600 MBytes for a single album), it’s heavy to transport and stream and, at last, does not support tagging (so generally you can’t organize/explore your wav files collection by Artist name, Album name, Year, etc…).
A good idea is to compress somehow audio tracks and… here we go!
Absolutely the first big risk in this cases is to get lost in the chaos of audio codecs. Actually various codecs are available... so what's the right one for you? Well the answer is not simple... it really depends on your expectations and your audiophile skills.
Actually audio codecs may be mainly divided in to two groups:
Lossy vs. Lossless compressors.
A nice variety of lossy compressor is nowadays available (let’s cite OGG Vorbis, Microsoft WMA,MP3…). As, indeed, there are several differences across them, lossy compressors are generally based on psychoacoustic models that try to degrade in an “inaudible” manner the original signal in order to reduce the space required to store the file. The most common one is absolutely MPEG Layer 3 compressor, widely known as MP3.
MP3, used with a decent bit rate (192 kbps or more) is a very popular choice. The high compression ratio (it can store an entire album in about 100 MBytes) as well as the good space/quality tradeoff made this codec the standard de facto for handheld music. Nowadays it’s absolutely the most supported audio format (nearly every software and hardware music player has a support for MP3 files). Of course MP3 is a lossy format. It’s algorithm is mainly based on psychoacoustic models that discard certain frequencies, apparently less audible by human ears. So, aside from the bit rate used (of course an higher bit rate can improve the overall quality), compressing an audio signal using MP3 (or any other lossy compressor) implies a certain loss of information and an overall degrading of the original waveform.
Apart from the lossy encoders there is another way to compress audio tracks: Lossless compressors.
Differently from the previous ones a lossless compressor (as per definition) does NOT alter, filter or change in ANY WAY the acoustic data.
What I mean is that compressing an original WAV soundtrack with a lossless compressor and decoding it back into another wav file (Original WAV -> Compressed file -> Decompressed WAV) will give back an exact bitwise copy of the original source file.
On the other side lossless compressor does not generally offer an high compression ratio compares to lossy ones (it's really variable but is really hard to go under 50%)
Now, let me guess what would be the obvious question: “How can lossless compressors achieve space saving without degrading in any way the original waveform?". The answer is somehow simpler than the lossy case.
Lossless compressor generally does not use any form of audio processing, psychoacoustic models or other. They just act on the raw byte data of the files. The main idea is to compress data in a completely reversible manner.
To convince yourself just think on zip-software… they compress and decompress data without loosing any kind of information achieving sometimes very high compression ratios.
Now, lossless audio compressors works in a very similar way. The trick is to optimize the compression algorithm in order to give better performances when used with audio files.
The choice of lossless codecs is a bit restricted. At the time of the writing these are the mainly available lossless compressors: Microsoft WMA Lossless codec, Apple Lossless Encoder, Monkey’s Audio and FLAC (Free Lossless Audio Codec).
The first three are proprietary formats. FLAC is on the other side an Open Source compressor. I’ll not spend many words on comparison of these compressor and how they work. I’ll just say that in my opinion FLAC it’s probably the best choice: it’s has a large software support (supported by Winamp, Windows Media player and many other software players as it is an open patent…) and is experiencing a growing acceptance on hardware devices (actually several high end hardware players support FLAC, such as Squeezebox, etc)
As told before, the kind of compressor is really a lifestyle choice. Most of the people can’t take the difference between an original soundtrack and a low quality 128kbps MP3. Some others can’t stand the “wavy water sound” coming even from 320 kbps MP3s.
So if you’re a wary audiophile and want to rip and store your beloved CD collection on your hard disk, FLAC should be definitively the best approach to do this.
At this point we have two choices:
How to RIP (and play of course) your CD collection using FLAC compressor.
It’s now time to enjoy your “quality and space proof” album collection !