Recently on the Internet OTR Digest there’s been a suggestion that Flac, a lossless audio compression system, should be used for old-time radio instead of the lossy MP3 standard. Before I get into an examination of the systems, I should probably give you the disclosure that I keep uncompressed audio files (AIFF format) of any high-quality OTR files I have, while I am also perfectly comfortable using low-bitrate MP3 files for listening. That is, while I use MP3 I don’t depend on it for mission-critical files.

Ok, let’s use a real-world file - and note I am not looking at compression time, since I don’t think the time it takes to compress a file is particularly relevant. This morning, I created an uncompressed 44kHz 16-bit stereo file that runs exactly 59:15, file size 627,102,044 bytes (that’s ~598 Megabytes). I first compressed the file with flac from the command line, using default settings (that is, flac filename.wav). The resultant lossless file was 245,067,147 bytes, roughly 233 megabytes. Not bad, I suppose. I then re-compressed that same file using the best compression (flac –best –verify filename.wav to be exact), for a slightly better result of 241,472,932 bytes or ~230 megabytes.

I then compressed the same file using 224kbps joint-stereo MP3 encoding (for those lame lovers out there, I used the command line lame -b 224 -q 2 -m j), which I’m pretty sure everyone will agree is overkill for OTR, and definitely overkill for the real-world recording I made as well. Note that this 224kbps file would burn to a perfectly-respectable audio CD indistinguishable from the original by any human I know…about the only thing I wouldn’t want to do with it is back-convert to uncompressed for editing and then re-compress, since every lossy compression cycle removes more data. The size of this file is 99,542,308 bytes…that’s right, about 95 megs. I can’t hear any difference; admittedly I’m in my fifties, but I’d doubt anyone would hear any difference at that high a bitrate.

(For giggles, I also compressed this same file to a 32kbps mono MP3 using lame -b 32 -q 2 -m m, something that is perfectly serviceable to add to my Inno or Nexus for listening while walking, or to play overnight - yeah, I keep news, OTR, and other programming playing all night long so if I wake up I have something to help lull me back to sleep. Anyway, the 32kbps mono file came out to 14,220,121 bytes, about 13.5 megabytes. I can clearly hear the difference between the original and this file, but I don’t particularly mind the difference. I’m sure it would be more of an issue if it were primarily music programming instead of talk, but I could and do listen to files at this bitrate.)

Bottom line based on these real-world tests: If you have a file important enough to archive, leave it uncompressed; space is cheap, and the savings aren’t really significant. If your purpose for the file is to use as a listening copy, using flac over MP3 doesn’t make one bit of sense, even if your goal isn’t to fit a bazillion files on one CD. About the only thing flac has going for it is the “bragging rights” of using a lossless compression format that isn’t supported by many playback applications or portable players.