1. Introduction to AAC AAC is the abbreviation of Advanced Audio Coding (Advanced Audio Coding). This music format has higher quality than MP3. AAC is developed by Fraunhofer IIS-A, Dolby and AT&T** *An audio format developed with the same company as part of the MPEG-2 specification. The algorithm used by AAC is different from that of MP3. AAC improves encoding efficiency by combining other functions. AAC's audio algorithm far exceeds some previous compression algorithms (such as MP3, etc.) in terms of compression capabilities. It also supports up to 48 audio tracks, 15 low-frequency audio tracks, more sampling rates and bit rates, multiple language compatibility, and higher decoding efficiency. In fact, the AAC algorithm was completed in 1997. It was called MPEG-2 AAC at that time because it was still regarded as an extension of the MPEG-2 standard. However, as the MPEG-4 audio standard took shape in 2000, MPEG-2 AAC was also used as the core of its encoding technology, and some new encoding features were added, so it is also called MPEG-4 AAC. AAC does not see that the high frequency part of the spectrum is better than MP3 with the same frequency, or even worse than the latter. But you can also easily find that the AAC signal is obviously denser and thicker than MP3! The actual listening effect can be left to you to experience for yourself. What can be guaranteed is that AAC is indeed much better than MP3! In short, AAC can provide better sound quality while reducing the size of MP3 files by 30%. Features of AAC: ① Improved compression rate: higher sound quality can be obtained with smaller file size; ② Multi-channel support: can provide up to 48 full-range channels; ③ Higher resolution: supports up to 96KHz Sampling frequency; ④Improved decoding efficiency: decoding and playback takes up less resources; Dolby Laboratories’ conclusion: ①128Kbps AAC stereo music is considered by experts to be less noticeable than the original uncompressed audio source; ②AAC format operates at a bit rate of 96Kbps The performance exceeds the 128Kbps MP3 format; ③ At the same 128Kbps, the sound quality of the AAC format is significantly better than MP3; ④AAC is currently the only Internet radio format that can obtain "excellent" in all EBU audition test items.

Generally speaking, AAC can be said to be an extremely comprehensive encoding method. On the one hand, the characteristics of multi-channel and high sampling rate make it very suitable for future DVD-Audio; on the other hand, the high sound quality at low bit rate makes it very suitable for future DVD-Audio. It is also suitable for mobile communications, Internet telephony, online broadcasting and other fields. It is really versatile!