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What is AAC?
AAC is a lossy compressed format for digital audio.
Advanced Audio Coding (AAC) is a standard for lossy digital audio compression originally designed as a successor to the MP3 format. It became standardized in 1997 alongside the MPEG-2 Part 7 standard.
While MP3 has remained popular, many commercial broadcast stations and HD radio have adopted AAC. It’s also used in cell phones, game consoles, and eReaders, and can be encoded for digital music files with .m4a or .mp4 file formats.
How AAC Works?
AAC has multiple modes, with the most common being HE-AAC (High Efficiency Advanced Audio Coding), which allows to achieve high compression rates by employing techniques such as frequency prediction and temporal prediction.
HE-AAC was developed by Coding Technologies (later bought by Dolby Laboratories) as a lossy compressed format for digital audio transmission or storage. It uses a psychoacoustic model to reduce data while maintaining good quality for human perception.
Other common modes include the lossless encoding mode LC-AAC and the stereo-compatible formats MPEG-4 SLS and MPEG-4 ALS:
- LC-AAC is a lossless encoding mode that allows you to encode audio in its original quality, without any degradation of data. This makes it ideal for users who are looking for high quality audio files but do not wish to sacrifice disk space by using lossy compression.
- MPEG-4 SLS (Stereo Lossless Surround) can be used on both stereo (2 channel) content as well as multi channel surround sound material without any compromise in sound quality or compatibility
MPEG-4 SLS (Stereo Lossless Surround) supports both stereo and multichannel surround sound content without compromising quality or compatibility. AAC-LC’s versatility complements these other modes by providing a balanced solution for high-quality audio at efficient bit rates, which is critical for mobile and streaming applications.
Cloudinary supports AAC for upload and delivery. You can sign up here and read more about audio transformation in our documentation.
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