AAC Audio Codec (Advanced Audio Coding)
AAC is a lossy audio compression method developed by MPEG Group (Moving Picture Experts Group). It was specified as a further development of MPEG-2 in the MPEG-2 standard. During development, known weaknesses and issues in the MP3 encoding process were taken into account and greatly improved.
Well, the sound quality is excellent. However, it comes at a price, and very few operators of video forums and vlogs will invest in the costs of the license. This is where open source solutions like FAAC (Free Advanced Audio Codec) become interesting. The AAC audio codec has the great advantage that it can deliver (reasonably) good stereo quality at bit rates around 64 kb.
As for the H.264 video codec, several profiles have been defined for the AAC audio codec. In this case, however, from the International Organization for Standardization, or ISO for short. Above all, they make it easier for hardware manufacturers to use this compression method. Here we will briefly introduce the most common profiles.
Low complexity profile (AAC-LC)
Designed primarily for medium to high bit rates. This profile is compatible with most AAC-compliant hardware end devices. Due to its advantages in terms of encoding and decoding efficiency and better sound quality at higher bit rates, this profile is the most common profile among all hardware manufacturers and music store providers.
Main Profile (Main AAC)
This profile is designed for low to medium bit rates. Due to its much higher encoding and decoding performance compared to AAC-LC, this profile is relatively inefficient. The sound quality at medium bit rates is better than that of the AAC-LC profile, but in no way justifies this inefficiency.
High Efficiency Profile (HE-AAC)
This profile is also designed for low to medium bit rates. However, thanks to the technical implementation of spectral band replication, or SBR for short, it offers significantly better quality at very low to medium bit rates than with the other two profiles. The high efficiency profile of the AAC audio codec is mainly used in streaming. However, at higher bit rates, the sound quality of the AAC-LC profile is better.
