This is an article by Whitson Gordon I read the other day on LifeHacker. Contains some really useful information about audio quality. Worth a view.
Q: Dear Lifehacker,
I hear a lot of arguing about “lossless” and “lossy” music these days, but I’m having a hard time getting straight answers. Does bitrate really matter? Can most people tell the difference between high and low bitrate music files?
A: We understand your frustration. While you may have some idea about what bitrate is, the “can audiophiles really tell the difference” argument has raged on for quite some time, and it’s hard to get people to drop their egos and actually explain what these things mean and whether they really matter. Here’s a bit of information on bitrate and how it applies to our practical music listening experience.
What Is Bitrate?
You’ve probably heard the term “bitrate” before, and you probably have a general idea of what it means, but just as a refresher, it’s probably a good idea to get acquainted with its official definition so you know how all this stuff works. Bitrate refers to the number of bits—or the amount of data—that are processed over a certain amount of time. In audio, this usually means kilobits per second. For example, the music you buy on iTunes is 256 kilobits per second, meaning there are 256 kilobits of data stored in every second of a song.
The higher the bitrate of a track, the more space it will take up on your computer. Generally, an audio CD will actually take up quite a bit of space, which is why it’s become common practice to compress those files down so you can fit more on your hard drive (or iPod, or Dropbox, or whatever). It is here where the argument over “lossless” and “lossy” audio comes in.
Lossless and Lossy Formats
When we say “lossless”, we mean that we haven’t really altered the original file. That is, we’ve ripped a track from a CD to our hard drive, but haven’t compressed it to the point where we’ve lost any data. It is, for all intents and purposes, the same as the original CD track.
More often than not, however, you probably rip your music as “lossy”. That is, you’ve taken a CD, ripped it to your hard drive, and compressed the tracks down so they don’t take up as much space. A typical MP3 or AAC album probably takes up 100MB or so. That same album in lossless format, though—such as FLAC or ALAC (also known as Apple Lossless) would take up closer to 300MB, so it’s become common practice to use lossy formats for faster downloading and more hard drive savings.
The problem is that when you compress a file to save space, you’re deleting chunks of data. Just like when you take a PNG screenshot of your computer screen, and compress it to a JPEG, your computer is taking the original data and “cheating” on certain parts of the image, making it mostly the same but with some loss of clarity and quality. Take the two images below as an example: the one on the right has clearly been compressed, and it’s quality has diminished as a result. (You’ll probably want to expand the image for a closer look to see the differences—look at the fox’s ears and nose).
Remember, of course, that you’re still reaping the benefits of hard drive space with lossy music (which can make a big difference on a 32 GB iPhone), it’s just the tradeoff you make. There are different levels of lossiness, as well: 128kbps, for example, takes up very little space, but will also be lower quality than a larger 320kbps file, which is lower quality than an even larger 1,411 kbps file (which is considered lossless). However, there’s a lot of argument as to whether most people can even hear the difference between different bitrates.
Does It Really Matter?
Since storage has become so cheap, listening to higher-bitrate audio is starting to become a more popular (and practical) practice. But is it worth the time, effort, and space? I always hate answering questions this way, but unfortunately the answer is: it depends.
Part of the equation is the gear you use. If you’re using a quality pair of headphonesor speakers, you’re privy to a large range of sound. As such, you’re more likely to notice certain imperfections that come with compressing music into lower bitrate files. You may notice that a certain level of detail is missing in low-quality MP3s; subtle background tracks might be more difficult to hear, the highs and lows won’t be as dynamic, or you might just plain hear a bit of distortion. In these cases, you might want to get a higher bitrate track.
If you’re listening to your music with a pair of crappy earbuds on your iPod, however, you probably aren’t going to notice a difference between a 128 kbps file and a 320 kbps file, let alone a 320 kbps file and a lossless 1,411 kbps file. Remember when I showed you the image a few paragraphs up, and noted that you probably had to enlarge it to see the imperfections? Your earbuds are like the shrunken-down version of the image: they’re going to make those imperfections harder to notice, since they won’t put out as big a range of sound.
The other part of the equation, of course, is your own ears. Some people may just not care enough, or may just not have the more attuned listening skills to tell the difference between two different bitrates. This is something you can develop over time, of course, but if you haven’t yet, then it doesn’t particularly matter what bitrate you use, does it? As with all things, go with what works best for you.
So how high of a bitrate should you use? Is 320kbps okay, or do you need to go lossless? The fact of the matter is that it’s very difficult to hear the difference between a lossless file and a 320kbps MP3 (though you can run this test to find out if you can hear the difference). You’d need some serious high-end gear, a very trained ear, and a certain type of music (like classical or jazz) to hear the difference. For the vast majority of people, 320kbps is more than adequate for listening. You don’t need to pain yourself with finding lossless copies of all your favorite songs. Photo by Marcin Wichary.
Other Things to Consider
All that said, lossless file types do have their place. Lossless files are more futureproof, in the sense that you can always compress music down to a lossier format, but you can’t take lossy files back to lossless unless you re-rip the CD entirely. This is, again, one of the fundamental issues with online music stores: if you’ve built up a huge library of iTunes music and one day decide that you’d like it in a higher bitrate, you’ll have to buy it again, this time in CD form. You can’t just put data back where it’s been deleted. When possible, I always buy or rip in lossless just for backup purposes, but I’m a little overly obsessive—MP3 is a great standard, and it isn’t likely to change anytime soon, so unless you plan on converting your music at a later date, you’re probably fine just ripping or buying in MP3 format. Photo by Charlotte L.
All of this is merely scratching the surface of the audiophile’s challenge. There is of course a lot more to talk about, like variable bitrate and coding efficiency, but this should provide a simple introduction for the uninitiated. As I said before, it all depends on you, your hearing, and the gear you have at your disposal, so give it a shot. Compare two tracks side by side, try out some different audio formats for awhile, and see what it does for you. At the worst, you’ve spent a few hours listening to some of your favorite music—and isn’t that what this is all about anyway? Enjoy it!
P.S. Many of you undoubtedly have your own views on the subject, whether you’re a bitrate-hungry audiophile or if you belong to the “if I can hear it, it works for me” philosophy. Share your thoughts and experiences with us in the comments.
Originally found in: http://bit.ly/1pg4Zg6