Which Lossless Audio Codec, and Why?

deadsquid puts forth a worthy follow up question to last week's query on audio codecs: "I'm about to re-rip my entire CD collection for the fourth time. I don't want to do it again, so have decided to invest in a small(ish) array and use a lossless codec to create a reference set of my music. From the reference, I plan on transcoding to a variety of bitrates (depending on where the final product will end up) and whichever format of the week suits the device(s) the transcoded content will ultimately sit on. I don't particularly care about encoding time, but would like something that transcodes nicely to MP3, WMA, OGG, and other formats in a reasonable length of time. I would like to ensure that track metadata is maintained in the reference, and is easily transferable when transcoded. I also want something that's not proprietary to an individual's or small group's whims. I'm thinking FLAC, but was wondering if other people had better experiences with other codecs. If you were to use a lossless encoding format, which would you use, and why?"

Comments

Definitely FLAC

[Punboy]

I would definitely go with FLAC. No patent/IP worries, no licensing... its opensource... and it transcodes very nicely. I use it personally for my entire collection except what I switch over to my iPod, which is when I transcode it to 192Kbps AAC. Don't use Apple's Lossless, it has licensing issues and Linux decoders are buggy at best. Don't use RAW or WAV cause um... they're too big.

comparisons of lossless compression

[belmolis]

I made some comparisons of lossless compression techniques a while back. This web page contains the results of my own tests (for speech data) and links to the tests I found (for music). I use FLAC.

Re:Again?

[mellon]

You can't edit mp3s. Well, you can, but the results aren't good. You have to decompress the mp3, do your editing, and recompress, and chances are that you're going to get artifacts when you do this. So if you ever intend to use an audio file for any kind of editing, you really want it stored losslessly.

At Diamond Mountain University, we typically record all our classes, at 16bit 44khz mono, which consumes a substantial amount of disk space. When people record directly to MP3 it's a huge hassle because I can't take the audio and do dynamic range compression on it without creating artifacts, which means that you can't listen to it on your car stereo unless you have a luxo-mobile with really good sound baffling.

Right now I store all this stuff as AIFF files, but the idea of converting them to FLAC files is definitely attractive.

Re:Consider longevity of the codec

[belmolis]

the reason WAV has been around for so long is that it's just doing a direct read of the bits on the audio CD, and dumping them to a file.

Not exactly. WAV is a FILE format, not an audio representation format. The audio data can be in any of dozens of formats, many of them involving lossy compression. One of the registered audio data formats (with ID 1) is straight PCM data, that is, uncompressed audio in the usual format. WAV files often contain straight PCM data, but they don't have to. (I've got some lecture notes on audio data and file formats here.)

Re:Flac for sure

[booch]

uh...why not create wave files and then compress the hell out of it with a separate data compression program

That's pretty much what FLAC is -- it's a specialized data compression program. To a "normal" data compression program (ZIP, gzip, etc.), audio data looks pretty random, so it wouldn't do a very good job. The important lesson here: knowing more about your data allows you to compress it better.