Audio Format Transcoding for Compatibility?

brandorf asks: "With the multitude of compressed audio formats that are available today, (MP3, Ogg, AAC, and FLAC to name very few) our music libraries start to spread across quite a few different formats. While this isn't a problem for desktop/media PC use, as programs like Winamp or iTunes have plugins available for almost every format. However, when it's time to start using a portable unit, it's unavoidable that some files will get transcoded. Have there been any studies or experiments as to how similar the codecs really are? Will transcoding from Format A to B sound worse than going from A to C? What's your experience with this?"

Comments

Hydrogen Audio have tested this

[doofusclam]

http://www.hydrogenaudio.org/forums/index.php?show topic=32440

The site insists on proper ABX tests too, not some thirteen olds insisting they can tell the difference between FLAC and Monkey's Audio codecs.

Re:Hydrogen Audio have tested this

[Anonymous Coward]

...not some thirteen olds insisting they can tell the difference between FLAC and Monkey's Audio codecs.

I'm twenty-one, and I can tell the difference: FLAC is GPLed, Monkey's Audio is not.

Re:Hydrogen Audio have tested this

[Fweeky]

The codec portions (libflac and friends) are BSD licensed; the FLAC tools themselves are GPL.

WavPack is another nice lossless BSD-licensed codec, which is more advanced in some respects, if not as well supported.

If you're that concerned...

[Anonymous Coward]

Use a lossless format for archival purposes (any format really since you won't use it on your portable), then use MP3 for everything else. MP3 is the only thing that pretty much every portable can play. OGG and Windows Media are a close second but I would never consider Windows Media format.

Quality Loss

[Sebilrazen]

I've noticed significant reduction in lows and an unsettling amount of distortion when I go from vinyl to wax cylinder.

Re:Quality Loss

[dstone]

I've noticed significant reduction in lows and an unsettling amount of distortion when I go from vinyl to wax cylinder.

Run a green, felt-tipped pen around the outside of the wax cylinder. It will restore the low frequencies lost from vinyl. I would describe the restored sound as quite earthy, rather than airy though. If airy is what you're going for, I suggest making make two light applications of green felt-tipped marker, rather than one heavy one. This however, could result in very cinnamon flavored mids and highs though, so be careful. In a pinch, you could use a black felt-tipped pen, but don't just use any old Sharpie. Use something really expensive, preferably immediately after writing a page of taoist scriptures on parchment paper. Northern taoist is fine, but southern taoist would be better, especially if you listen to a lot of jazz. Unless it's smooth jazz. Oh, and insulate yourself with 24K gold arch supports before trying any of this, otherwise the earth's own vibrations could mellow your high frequencies, resulting in distinctly cedar-flavored vocals.

FLAC, ALE, etc. are the way to go

[Anonymous Coward]

Seriously. Encode your music in a lossless format, then transcode it to whatever lossy format you use on the go. Sure, it's much bigger, but it will be bit-for-bit accurate! Even if you can't tell the difference on your $50 computer speakers and bundled iPod headphones, you can feel good because you know it's better.

Also, it will get you laid.

Love, your hard drive manufacturer.

Why not just keep lossless copies?

[zoeblade]

Hard drive space is plentiful. Just rip everything to a lossless format, such as FLAC, or even .wav or .aiff if you can't be bothered with the hassle, then make a convenient shell script to convert everything into another format as and when required. That way, you get the best sounding MP3s or Ogg Vorbis files with none of the bad side effects of transcoding, and as soon as any given codec is improved or replaced by a better one, you won't have to worry about not taking advantage of the shiny new algorithms.

Just an FYI

[Andy Dodd]

Requantizing audio of a given format to reduce its bitrate is likely to cause less of a problem than switching formats.

Simply put, each format has different criteria on what information is thrown away and what is not. Thus, for example, something that MP3 may keep but AAC throws away will not be present if you transcode from AAC to MP3, IN ADDITION to losing anything that AAC keeps but MP3 throws away. The same holds true in reverse.