What is AAC?
AAC, Advanced Audio Coding, is a technique of compressing digital audio files. Officially, the MPEG-4 standard is most used to create small digital audio files. The current variant is specified in the ISO/IEC 14496-3 standard.
AAC is conceptually similar to the ubiquitous MP3 format. Like MP3, it takes advantage of human hearing deficiencies and dispose of digital bits corresponding to sounds unlikely to hear. The human hearing system does not hear quiet sounds in the presence of loud sounds similar to frequency; For example, a voice conversation cannot be heard, while Jumbo jet flies low above the head. This phenomenon, known as auditory camouflage, allows you to eliminate data with minimal loss of loyalty.
Like MP3, AAC is a loss algorithm, which means that the original digital sound cannot be re -created from compressed bits. When it comes to sound loyalty, there is no loss of data if the compressed sound is properly coded. Claims to AACIZE compared to mp3 inIn this respect: While MP3 requires a transparency of approximately 256 kilobites per second (KBPS), AAC can achieve the same quality at 128 kbps. This allows AAC files to be about half the size of MP3 files of the same quality and one tenth of the size of the digital data of the CD.
AAC provides several other advantages over MP3. It is able to handle much higher and lower sound frequency, provides up to 48 sound channels, and allows the creation of low latency of the sound necessary for two -way communication. For example, AAC can be used to compress telephone conversations while running, while using MP3 would introduce delay in sound. AAC also allows you to manage digital rights or DRMs that can be used to control how an audio file is used.
area where AAC stands out in low -bit compression. For example, sound books do not have a lynamic scope of music because they consist of little more than a mLuthe outside word. It potentially allows a much higher level of compression. The use of MP3 at such levels of compression produces scratches, hissy compressed sound, unlike low quality cassette records. AAC was specially designed for proper processing of such applications.
Unlike MP3, there is no public, free version of AAC encoding algorithms. All AAC users must license this technology from Via Licensing Corporation. AAC is most commonly used in a number of portable iPod Apple Computer music transmissions and is part of the new generation DVD specifications.