Mp3 audio to mp4 audio

hey can anyone tell me any free software to convert mp3 to more reduced form like mp4 ???

Aheads MP4 encoder (included in all recent versions of Nero) and a frontend.
http://www.rarewares.org/aac.html - NEncoder
You probably need to decompress the MP3s first and you can do that by using LAME and wrapping it all up on a batch file (*.bat).
//Danne

rememer that compressing an already compressed lossy audio file such as mp3 will result in quality loss. Though if the mp3 source is say 320kbps you probably won’t hear a difference, but at 128kbps you can likely hear the difference side by side

I do not agree. Chances are:

  1. The bitrate of the final file is LOWER than the bitrate of the original file = quality loss. For example, if you compress a 128 kbps MP3 to a 112 kbps MP4 you will end with less quality (very easy to understand).

  2. The bitrate of the final file is HIGHER than the bitrate of the original file = same quality, the final file only takes more space. This is because any type of conversion with a lossy algorithm (like MP3 and MP4) is non reversible. For example, if you convert a 128 kbps MP3 to a 256 kbps MP4 there will be space filled with zeros (or very little bits) because of the higher bitrate which was lost during the compression of the original MP3 file.

  3. The bitrate of the final file is EQUAL to the bitrate of the original file = same quality. Probably, if you are using the latest version of the same compression algorithm, you will end up with a file which will take less space than the original.

It’s not going to happen, try it yourself…
//Danne