Everyone's always asking me about bitrates for music, and what's appropriate. My advice in 5 easy steps.
1) Source should be a record, CD or DVD.
2) Choose FLAC, OOG first and VBR m4a or mp3 if you must.
3) When dealing with lossy formats like MP3, aim for VBR with an Average BitRate of 192-320, and turn off joint stereo to get full stereo.
4) When space needs to be considered, use short playlists with short songs and reduce to 96-160 at VBR or 160-256 CBR, and try joint stereo on.
5) Test your ears. Find out what you like and use it as a baseline.
Now for those who need a little bit more information about the who and the what, please look below:
1) Source should be a record, CD or DVD.
Secure the highest-quality version available for your digital archive, downloading versions online should be a last resort after your original copy has already been damaged if your artist has no physical copies avilable in your area, you should be wary of step 2 when downloading a digital copy.
2) Choose FLAC, OOG first and VBR m4a or mp3 if you must.
There is great variety in the amount of frequency of music complexity. Most music will build towards sections and then change greatly at a particular moment, so avoid formats like mp3 that allow people to encode in Constant Bit Rate without realizing it. If you are backing up your own music and prefer to use MP3, see step 3.
3) When dealing with lossy formats like MP3, aim for VBR with an Average BitRate of 192-320, and turn off joint stereo to get full stereo.
Avoiding Constant Bit Rate is already helping you out immensely in making sure that you have a high-end music library, and tests do demonstrate that quality levels above 160 are difficult to distinguish, depending on the quality of your equipment. However, for that time when you do purchase high-end studio headphones for the home, you'll want to be able to enjoy all of your tracks the way they were meant to be heard.
4) When space needs to be considered, use short playlists with short songs and reduce to 96-160 at VBR or 160-256 CBR, and try joint stereo on.
When exporting to a mobile device like an mp3 player, variety is generally the goal. Pick a maximum song length 6, 9, 12 minutes, and ensure your playlists are made up of less than 100 songs each shorter than that length. Several songs I love are excluded at the 12 min limit, but these songs often don't finish playing anyway. If your player is not VBR compatible, average stereos and earbuds will not demonstrate much loss in quality at 160-256. Invest in a deck or device that supports VBR if space is still an issue, or export at a variety of bitrates for different playlists.
5) Test your ears. Find out what you like and use it as a baseline. Known as an ABX test.
Take highly different styles of music export some different versions and listen to them with the best equipment you have. Find the qualty level where you notice a loss of quality and archive a step above. Then export to mobile devices at your baseline, or a step lower, depending on your personal desires for quality versus variety.
For additional reading, please look into the following sites:
http://gizmodo.com/5251247/the-great-mp3-bitrate-test-my-ears-versus-yours
http://www.codinghorror.com/blog/2005/12/variable-bit-rate-getting-the-best-bang-for-your-byte.html
http://www.maximumpc.com/article/do_higher_mp3_bit_rates_pay_off?page=0,3
http://www.noiseaddicts.com/sound-challenge/?selection=1&submit=Submit
http://www.hydrogenaudio.org/forums/index.php?s=a282bb8e7baba13f1ce3fba99b6d6abc&showtopic=30637&st=25
