Tech Tip:MP3 and the Pro Studio
By Craig Anderton
As engineers and/or musicians, we want the best-sounding recordings possible. Okay … but then the MP3 format came along, which some call data compression, but is actually data omission. All those nuances we slaved over have vanished, trampled by a mercilessly efficient coding algorithm. What’s more, the reduced file size has encouraged the downloading phenomenon that is re-shaping the record industry—whether for better or worse remains to be seen.
But does the MP3 format have anything to offer those involved in professional recording? Read on …
Music To Go; The Reality Test
Note the spectra for a standard 44.1kHz stereo WAV file (top)
and an MP3 version encoded to 64kbps stereo (bottom).
Above 8 kHz or so, response in the MP3 file falls off a cliff
We’ve all heard of the musicians who don’t sign off on a recording until they’ve heard it through a car radio. This makes sense: not only does it test a mix’s real-world transportability, but road noise obscures any subtleties, so that you find out what truly stands out in the mix. For example, you may find out that the guitar figure you could hear perfectly over the studio monitors needs to come up a bit in level to match the other instruments in the mix.
MP3s exhibit a similar phenomenon at low bit rates. Below 96kbps in particular, if your mix can survive the MP3 torture test, it can probably survive anything. There seems to be a correlation between mixes that can hold up at low bit rates, and their ability to sound good over a variety of systems. Although the following illustration shows the main difference as relating to high frequencies, low-level information also takes a hit with MP3.
Are Your Songs in Order?
Portable MP3 players provide a great way to test out song orders. When you’re assembling an album, do a rough assembly into a portable MP3 player, and listen to it when walking around, doing yard work, exercising, food shopping (added bonus: it can drown out the lame background music in your local supermarket), or whatever. Repeated listenings can reveal flaws in song orders that you might not catch otherwise.
Creating MP3 Files
Programs that can "rip" Red Book Audio files to MP3 are cheap and plentiful—but converting WAV or AIF files can be more problematic. Fortunately, you likely have software that can already do this. Digital audio editors such as Adobe Audition, Steinberg Wavelab, BIAS Peak, Sony Sound Forge, etc. can save WAV or AIF files in a variety of MP3 formats, at a choice of bit rates.
Furthermore, many DAWs and music-making programs can export audio in MP3 format. While intended for converting multitrack recordings into something you can send over the web or load into an MP3 player, no law says you can’t just load in a WAV or AIF file and convert that. However, note that because the industry-standard Fraunhofer MP3 algorithm needs to be licensed, MP3 export capability may be optional at extra cost.
MP3 Recorders: Not Just Toys
The MP3 format has even worked its way into recording, with small, hand-held devices (such as those TASCAM, Korg, Edirol, etc.). These perform no-moving-parts recording to CompactFlash or other types of memory cards, and offer decent sound quality. These types of recorders have several possible applications:
With a quality mic, the results can be usable even in pro situations. Sound effects are usually layered sufficiently in the background so that the data omission isn’t as problematic as it would be for critical musical recording.
Because of the compact size, these small recorders are easy to carry around for capturing any inspiration you might have. For some instruments, the quality is good enough so that if you capture something really incredible, it can be brought over to your DAW and used. Most people will probably not recognize you’ve slipped an MP3 into the mix.
A "record everything" box.
These recorders are so easy to set up and use that it’s a no-brainer to just hook the thing up to your mixer’s stereo outs and then record rehearsals, jam sessions, the songwriting process, whatever. For example, the TASCAM PocketStudio 5 loaded with a 128 MB CompactFlash card can record about 2.2 hours of stereo music, or nearly 4.5 hours in mono! Yes, you really can record everything that goes on during a session if you’re so inclined.
An accessory when playing live.
Any MP3 playback device can store long samples—pads, sound effects, spoken word sections, drones, etc.—which can be played back and mixed into the set at strategic times. This is particularly good for "groove" type applications where you can mix what’s playing in and out of a tune, although of course, the material has to be something that doesn’t require synchronization.
I used to cart around a sampler for this sort of thing, then I downsized to Minidisc. But an advantage of MP3 is that even the anti-shock memory in a CD player or Minidisc has a harder time coping with the constant vibration of subwoofers woofing and people dancing than an MP3 player.
The Rodney Dangerfield of Pro Audio?
MP3s and other data compression formats don’t get much respect from pro audio types, because … well, because they simply aren’t "CD-quality," despite what the marketing weasels would like you to believe. Yet, in the pre-CD-R days, studios routinely ran off cassette copies for band members to carry around with them and play in their portable players. Data-compressed files are just the latest version of that concept, and if you make peace with their limitations, they do indeed have some surprising uses in today’s high-res world.