Formats
This time we’re going to take a look at delivery formats for digital audio. The mp3 is ubiquitous but is it good enough or just convenient?
MP3’s and other compressed audio formats have revolutionized the music industry. There was a time when sending a raw .wav or .aif rip of a song off a CD over email was impractical due to the size of the file (roughly 10MB per minute of stereo audio @16-bit). Along comes the mp3 and everything changed. Those same files were now compressed down to a manageable size – typically at least a 10th of the original size. Higher compression rates can make the files even smaller. By this point the mp3 has dominated as a preferred format for listening to music. The reasons why are several: small file size, header info that includes artist, song title, album and such, compatible with pretty much every computer and portable audio device (including cell phones) and they sound good. Or, do they?
For studio operators and producers, the mp3 has become a convenient way to send mixes to clients or as an easy means of exchanging ideas. They certainly sound good enough to get a rough idea of how a mix holds up. In fact, at higher bit rates (lower compression ratios) they can sound quite decent and if you buy music on iTunes and other such online stores, 256kbps is becoming more commonplace. It’s noticeably better than the 128kbps encoding rate. If you take the time though to compare your full .wav or .aif mixdown with an mp3 encoded from it (even at higher bit rates) you will notice a difference. The mp3 does not sound nearly as good. There is a good deal of subjectivity here – many people listen to everything on little ear buds and admittedly it’s hard to hear the sonic difference on those. But if you run the comparison through a really good sound system or good studio monitors you’ll hear in most cases that the mp3 is lacking in the high end and the low end. Why? Mp3 is a lossy format. That means that during encoding, certain frequencies deemed unnecessary are discarded to save room. The theory is that these frequencies are essentially inaudible to humans so by removing them you create a smaller file that sounds great. In my opinion, even though I use and listen to mp3’s constantly that discarded frequency information takes something else with it. I believe that some of the sonic landscape is sacrificed as harmonic content is compromised. Ultimately it’s up to you but I think the goal still remains to find a small-footprint delivery format that retains every bit of the original sonic information. So, does such a thing exist?
Yes, but with some reservations. First there’s FLAC (Free Lossless Audio Codec). It’s lossless so unlike an mp3, no data is discarded. The catch is that it’s quite a bit larger and requires support to play back – not all devices or systems support FLAC natively.
AAC (Advanced Audio Coding) is an Apple-proprietary format that while being lossy, compares more favorably against mp3s. Smaller size files encoded with AAC can sound better than higher bit-rate mp3s in fact. AAC is widely supported but you still may find some compatibility issues – such as AAC playback on certain portable music players.
WMA (Windows Media Audio) format is similar to AAC but it’s Microsoft’s proprietary format. It can be used in either lossy compressed form or lossless. Lossless formats again are much larger than lossy ones but even the lossy ones again have a favorable comparison against mp3s, much like AAC files do. WMA also is not supported on all portable devices.
There are other formats out there and some I didn’t mention here. Convenience is going to drive a lot of what we do but as studio owners and engineers, educating musicians and clients and letting them hear the difference can go a long way towards perhaps changing the landscape in favor of higher-quality compressed formats. Remember, any format is only as good as its original source!