Convert MP3 to AAC

MP3 (formally MPEG-1 Audio Layer-3 or MPEG-2 Audio Layer-3) is a digital format for storage of audio files as well as for audio streaming. The format was designed by MPEG programmers. It is one of the most required codecs for digital coding. The format is widely used in various file-sharing sites for evaluation downloading.

Due to lossy compression in this audio format, it is possible to compress CD tracks up to 1/10 of their original size while maintaining high playback quality. Moreover, it can be encoded at higher or lower bit rates to adjust the resulting quality. Overtones, which cannot be perceived by a human ear, are removed. Complex algorithms allow for smaller size of tracks. As a result, one compact disk can contain several hundred songs. MP3 is compatible with all most popular operating systems and supported by the most of modern DVD-players and music systems.

Prior to MP3 introduction, MPEG-1 had been widely used. That format contained not only audio data, but images as well. MP3 breaks an audio file into parts of the same length. When the processing is over, each part is packed into its own frame. It involves the technology of spectral limit that requires a continuous input signal to provide the use of two adjacent frames.

When spectral deleting is over, the file is to be compressed with mathematic methods. If necessary, compression rate can be changed, even inside the same frame. Files of 128 kbit/s have 11-fold compression. Further reduction of the file size will lead to significant deterioration in sound quality.

A proprietary format with lossy compression, which have been created as an alternative for MP3 with a higher quality of coding. Overtones out of human perception are being removed. AAC is two times less than MP3, which means 1/10 of CD digital data.

The format has being widely used since 1997 as the seventh release of MPEG-2 family. As it is supplied by hardware players, the format is highly demanded by music fans. It has been widely spread in Apple production and is being used by default in iTunes.

The format conception is similar to MP3, but it is more advanced. Being able to execute larger compression, it is represented as a separate segment of MPEG-4 standard which is used for creation of compact audio files. AAC is highly efficient with variable and continuous bitrate, with sampling frequency of 8-96 KHz.

The current version complies with the standard of ISO/IEC 14496-3. Compression is performed on the basis of auditory masking effect that provides with data reduction with no deterioration for sound quality.