Reduce Size of Mp3 Files
There are several reasons you might want to reduce the size of your mp3s. If you have a portable music player with limited storage, or want to share a song with your friend over internet, it is sometimes desirable to sacrifice some of the quality for quantity and variety.
How do you re-encode files? Here is a small software for it.
Its (appropriately) called MP3 quality modifier. Download it. Its a very small (<400 KB) stand alone file.
Extract it, Run it and it shows you the interface:
The suggested settings are shown. You can add files/folder to the list, set the quality, destination etc.
Leave the “Sample Frequency” and “Modus” as they are. I highly recommend that you keep the Bitrate Mode as “Variable”. 110-150 kbps range gives the best compromise, though you can (and should) try out other settings. Now just press start and go :)
Hearing is a very subjective phenomenon and you should try out a few different versions of the same file as well as a few different files over a period of time to find what combination of settings suits you best. The rule of thumb is, if you cant tell (or don’t mind) the difference, go for the lower bitrate.
Note : The following several paragraphs are not exactly essential, but you should read them eventually if you intend to do this regularly. Or skip to the end and read the excellent introduction given in the links.
The idea behind compression is this:
Unlike wav or flac, mp3 is a lossy format, which means that mp3 files are not true reproductions of the original sound, but are highly optimised to minimize the size without seriously affecting the audibility of the music.
The files are encoded at particular “bitrates”, which kind of indicate how much of the original data is kept, or how true the sound is to the original (aka master). Technically, bitrate is the file size per second of sound.
There are several factors that affect the quality of the output file, but as a rule of thumb, the higher the bitrate, the better it sounds, in the sense that it is closer to what the artist recorded.
Some of the more standard bitrates (measured in kbps) are 64, 96, 128, 256 and 320 kbps. In general, considering external factors that affect the sound you hear (environment, equipment, exposure time etc.) 128 kbps offers a fairly good compromise between size and quality.
So the idea is to re-encode the files to lower bitrates than they are to save space. You will find that the files are generally encoded at 192 kbps or more (right click on the file and view its properties/ID3 tags in your player to find its bitrate). You can covert them to 128 kbps without much loss of quality. As a rule of thumb, if you can’t (or barely) tell which is better by listening to them, use the lower bitrate.
For more detailed and accurate information on mp3 quality and bitrate visit this page, and maybe the wikipedia entry on mp3 format.
