“I’m a Mac user and I’m trying to encode my audio files (in AIFF format) into MP3s to upload to a music delivery site. When I follow the uploading criteria at the site my normally clean-sounding MP3s – encoded with SoundJam – end up sounding noisy after I’ve downloaded them from the site. Other artist’s files sound cleaner than mine. If I try to create the MP3s directly from Pro Tools, the MP3 site I use rejects them completely. How do I get better sounding files that a site will accept? Do these sites reprocess the files they receive?”
To answer your last question first (do sites reprocess the files) – that’s a definite maybe. They are often reprocessed in that the MP3s are converted into .WAV format [which is another issue entirely – going from AIFF to MP3 to .WAV… final quality = ???]. The files are often also encoded as “lo-fi” RealAudio files for preview purposes. The .WAV files are often used in the creation of audio CDs that can be purchased from many of these sites. The end MP3 that a user could download, however, should be the same one you uploaded, although the final answer to that question would have to come from them.
As far as the ‘better sounding files’ question is concerned, if your files normally sound good before you encode them, and also sound good after encoding as well, then you’re doing OK so far. An MP3 encoder such as SoundJam works on the Garbage In, Garbage Out principle, meaning that the end file can approach being as good as what you put in to begin with. Of course this means any master-quality audio you convert with one of the popular encoders for Mac out there today (SoundJam, MPecker, BladeEnc) should ideally reflect the quality of the original audio file. But bear in mind that encode rates for MP3s can go all the way up to 320kbps, yet most sites require lower rates, like 128kbps. 128kbps is the least passable 44.1kHz encoding rate for MP3s; any trained audio ear should be able to pick out the compression artifacts. However, they are easily downloadable because of their greatly reduced size (relative to the original audio file) and, for what it’s worth, can still be referred to as “near CD-quality”, which is ideal for marketing purposes.
Obviously each site has its own preferences about the exact types of files you must submit. Most MP3 encoders are easily configurable to accommodate those parameters. If you want to export audio as an MP3 file directly from Pro Tools, there are two main concerns as far as the typical MP3 site is concerned: the file name, and blank space at the beginning of the file. The file name absolutely HAS to have the “.mp3” extension at the end or a PC won’t recognize it, so if you’re having upload problems this is the first thing to check. The other problem could be caused by some sites’ preference for a bit of blank lead-in space [silence] at the beginning of the audio file. A tune that is literally ‘cued-up’ with no breathing room at the beginning doesn’t work into their master plan for some reason – and they don’t exactly specify why. No matter… this probably won’t be the first thing you’ve had to do in your life without knowing the reason behind it!