What is AAC format

AAC (Advanced Audio Coding), known in Chinese as "Advanced Audio Coding", appeared in 1997, based on MPEG-2 audio coding technology. By Fraunhofer IIS, Dolby Laboratories, At&t, Sony (Sony) and other companies to develop together, the purpose is to replace the MP3 format. In 2000, after the MPEG-4 standard appeared, AAC integrated its characteristics, adding SBR technology and PS technology, in order to distinguish it from the traditional MPEG-2 AAC also known as MPEG-4 AAC.

Advanced Audio Coding. A file compression format designed for sound data, unlike MP3, uses a new algorithm for coding, more efficient, and has a higher "price/performance". AAC format can make people feel that sound quality is not significantly reduced

Under the premise of more compact. AAC format can be converted or listened to with Apple itunes (six components)

Apple ipods, Nokia handsets and Sony Walkman also support audio files in AAC format.

Advantages: Compared to MP3 and other lossy formats, AAC format sound better, the file is smaller.

Inadequate: AAC is a lossy compression format, and the current popular ape, FLAC and other lossless formats than the quality of the "intrinsic" gap. In addition, the current speed of transmission faster USB3.0 and more than 16G large capacity MP3 is accelerating the popularization, but also make AAC head "small" aura ceased to exist.

Prospect: In the perspective of development, just as "HD" is being accepted by more and more people, "lossless" must be the absolute mainstream of the Future music format. The future of AAC's "lossy" format is not optimistic.

From MP3 to AAC

As early as 1987, Fraunhofer IIS began the research and development of EUREKA project EU147, Digital Audio Broadcasting (DAB), which is the predecessor of MP3. Through cooperation with Professor Dieter Seitzer, they developed the famous Iso-mpeg Audio Layer-3 compression algorithm. This algorithm was integrated into the MPEG-1 standard in 1993 and was put into use since then MP3. By the end of 1996 Fraunhofer IIS in the United States to obtain MP3 patents, and in 1998 foreign statement will be charged MP

3 of royalties. Since the beginning of the 1999, MP3 format has been widely popular. In particular, there are a lot of free MP3 music sites, MP3 Walkman also flooded into the market like floods, various factors prompted MP3 to become the most mainstream audio format. Despite the VQF, WMA and other challengers, but MP3 solid foundation so that it is still firmly seated in the boss's position.

But the audio format is like a computer hardware and software, after all, to upgrade, like tape is not eliminated by CD? and CDs will be replaced by Dvd-audio. Over time, MP3 more and more can not meet our needs, such as compression rate behind the Ogg, WMA, VQF and other formats, the sound quality is not ideal (especially low bit rate), only two channels ... So Fraunhofer IIS and At&t, Sony, Dolby, Nokia and other companies to cooperate to develop the "21st Century data compression way" of the Advanced Audio coding (for short AAC) audio format to replace the MP3 position. In fact, AAC's algorithm was completed in 1997, when it was called MPEG-2 AAC, because it is still the extension of MPEG-2 (MP2) standard. But as the MPEG-4 (MP4) audio standard was formed in 2000, MPEG-2 AAC was also the core of its coding technology, adding some new coding features, so we called MPEG-4 AAC (M4A).