The MPEG-4 Low Delay Audio Coder (a.k.a. AAC Low Delay, or AAC-LD) is audio compression standard designed to combine the advantages of perceptual audio coding with the low delay necessary for two-way communication. It is closely derived from the MPEG-2 Advanced Audio Coding (AAC) standard. It was published in MPEG-4 Audio Version 2 (ISO/IEC 14496-3:1999/Amd 1:2000)[1][2][3][4][5] and in its later revisions.[6][7]
AAC-LD uses a version of the modified discrete cosine transform (MDCT) audio coding technique called the LD-MDCT.[8] AAC-LD is widely used by Apple as the voice-over-IP (VoIP) speech codec in FaceTime.[9]
- ^ ISO (2000). "ISO/IEC 14496-3:1999/Amd 1:2000 - Audio extensions". ISO. Retrieved 2009-10-07.
- ^ ISO/IEC JTC 1/SC 29/WG 11 (July 1999), ISO/IEC 14496-3:/Amd.1 - Final Committee Draft - MPEG-4 Audio Version 2 (PDF), archived from the original (PDF) on 2012-08-01, retrieved 2009-10-07
{{citation}}: CS1 maint: numeric names: authors list (link) - ^ Heiko Purnhagen (2000-02-19). "AES 108th Convention: MPEG-4 Version 2 Audio What is it about?". Heiko Purnhagen. Retrieved 2009-10-07. [dead link]
- ^ Jurgen Herre, Fraunhofer Institut for Integrated Circuits (2000-03-08), MPEG-4 Low Delay Audio Coding (PDF), retrieved 2009-10-07 [dead link]
- ^ Heiko Purnhagen (2001-11-07). "The MPEG Audio Web Page - MPEG-4 Audio (ISO/IEC 14496-3)". Retrieved 2009-10-07. [dead link]
- ^ ISO (2007). "Low delay AAC profile - ISO/IEC 14496-3:2005/Amd 1:2007". ISO. Retrieved 2009-10-07.
- ^ ISO (2001). "ISO/IEC 14496-3:2001 - Information technology -- Coding of audio-visual objects -- Part 3: Audio". ISO. Retrieved 2009-10-07.
- ^ Schnell, Markus; Schmidt, Markus; Jander, Manuel; Albert, Tobias; Geiger, Ralf; Ruoppila, Vesa; Ekstrand, Per; Bernhard, Grill (October 2008). MPEG-4 Enhanced Low Delay AAC - A New Standard for High Quality Communication (PDF). 125th AES Convention. Fraunhofer IIS. Audio Engineering Society. Retrieved 20 October 2019.
- ^ Daniel Eran Dilger (June 8, 2010). "Inside iPhone 4: FaceTime video calling". AppleInsider. Retrieved June 9, 2010.