The most popular digital audio file formats, which include MP3 and AAC, employ lossy compression. Here, audio is split into frequency bands for each time interval. According to a model of the human auditory system, bands deemed inaudible due to the presence of louder frequencies are discarded or encoded using fewer bits.
Lossy compression results in much smaller files sizes, but reduced quality. Many of us won’t notice the difference when listening to our music on a portable player through a tiny earpiece, possibly with traffic noise in the background, but it’s most definitely present - especially at the higher compression ratios these codecs support.
When MP3 was developed more than 20 years ago, storage was expensive and PCs were lucky to have a 540MB hard drive - roughly 2,000 times lower in capacity than what’s popular today. Given that MP3 files are typically only 11 times smaller than uncompressed files, we can now afford to store more uncompressed audio. We also have audio formats at our disposal that use lossless compression, which slightly reduces the file size without affecting quality.
It might be easy to stick with the MP3 format when ripping tracks from CD, but all it takes to switch to uncompressed audio is to change a single setting. The ripping process should then take less time to complete, since less compression work is involved, although you won’t be able to store quite as many files in the same amount of space.
If you choose to adopt lossless compression for your portable media player, you’ll still be able to store around 600 tracks on an 8GB device. See Digital Home Advisor.
Here, we delve into the practicalities of recording and playing music tracks with small amounts of compression or even none at all.
Audio formats revealed
The most common format for uncompressed audio is Waveform Audio, which is usually referred to simply as WAV. Assuming a decent bit-depth and sample frequency, its quality is unsurpassed, since no information is discarded. Alternative formats can outdo it only by achieving the same quality and reducing the file size.
The most common format for compressed audio is MP3. This has various data-rate options, from 8 kilobits per second (kbps) to 320kbps. CD’s sampling rate of 44.1kHz and 16bit depth, for example, represents a reduction in file size of between four and 176 times.
As a lossy form of compression, though, the quality isn’t as good as it is with uncompressed audio, particularly at the lower bitrates.
AAC is a similar lossy format, although it’s estimated that the file sizes are about two-thirds that of MP3 for the same quality.
The two most common formats that use lossless compression (and sound as good as WAV) are Free Lossless Audio Codec (Flac) and Apple Lossless, often referred to as Apple Lossless Audio Codec (ALAC).
Also important to the audio quality are the sampling rate and bit-depth. These are measures of how many times per second the audio was sampled during recording and how many bits were stored per sample.
Files ripped from CD are fixed at 44.1kHz and 16bit, but in selecting music for download you should look out for higher quality sampling (such as 48-, 96- or 192kHz at 20- or 24bit). WAV, Flac and Apple Lossless all extend support beyond 44.1kHz/16bit.
For many years, hi-fi purists insisted that the earlier a component is in the playback chain the more important it is. The implication of this is that the CD player (or optical drive) is more important than the amplifier (or sound card) which, in turn, is more important than the speakers.
Working on this basis, if you want to improve the audio quality of music playback on a PC, the first line of attack should be to move from a lossy to a lossless format. While we wouldn’t disagree that this is vitally important, it would also be wrong to suggest that the hardware is unimportant. In fact, it could well be that you won’t notice the improvement provided by better-quality audio until you upgrade from the cheap audio hardware bundled with most PCs.
The best approach for listening to high-quality audio is to route the audio from your PC to a decent hi-fi system, taking the output from as early as possible in the playback chain.
If you really do want to listen to music on your computer, though, the easiest and cheapest upgrade would be to get a better-quality speaker set (speaker reviews). Don’t ignore your sound card (or chipset) and its associated amplifier; consider upgrading this to an external sound adaptor.
Rip audio files to a lossless format
Step 1. Although file-format compatibility depends on the playback software you use, your audio hardware might limit the sampling rate. Find out if your hardware is capable of 24bit audio at 96kHz and 192kHz by downloading the relevant test files from this site.
Step 2. These test files are in Flac format, which isn’t supported by Windows Media Player (WMP). Instead, download and install VLC Media Player. Try listening to the test files; if one or both won’t play then you’ll either have to stick with lower sampling rates (you can still use lossless compression) or upgrade.