AAC low delay (AAC-LD)
AAC-Low Delay (AAC- LD) was developed as an MPEG-4 coding based on Advanced Audio Coding (AAC) and combines the advantages of Perceptual Audio Coding( PAC) with the low delay times for two-way communication. The requirements for AAC-LD stipulate permissible delay times of 20 ms.
In addition, AAC-LD is characterized by good audio quality for music and speech. The delay time is always 20 ms and is independent of whether the data rate is 24 kbit/s, 48 kbit/s or 96 kbit/s. In contrast to AAC-LD, AAC compression has a delay time of more than 300 ms for a data rate of 24 kbit/s, about 170 ms for 48 kbit/s, and about 100 ms for 96 kbit/s. Only the G.-codecs optimized for voice communication have shorter delay times: G.711, G.721 and G.722.