Audio Codec (1) Sampling Number of Codec bit rate Description frequency channels General (medium to high bit rate) 640 kbps (max.) Belonging to Dolby Digital, 448 kbps (DVD, supporting multi-channel AC-3 Digital cable TV) -Multiaudio, used on DVD 384 kbps (ATSC) Pulse-code modulation, digital representation of an analogue signal by sampling the Varied magnitude of the signal at PCM -Up to 8 64 kbps (DS0) uniform intervals, used in digital telephone systems and digital audio in computers and CDs AAC - 8 – 96 kHz - Advanced Audio Coding, Adaptive Transform Acoustic 48, 64, 66, 132, 256 Coding, developed by Sony, ATRAC -- kbps used to store information on Minidisc, Digital Theatre System, used 768 – 1536 kbps (6- DTS -Multifor in-movie sound on film and channel) on DVD MP1 384 kbps Varied 1, 2 Lowest encoder complexity 256 – 384 kbps More complex encoder and (excellent) decoder, able to remove more 224 – 256 kbps (very of the signal redundancy and MP2 Varied 1, 2 good) to apply the psychoacoustic 192 – 224 kbps threshold more efficiently (good) 224 – 320 kbps More complex, directed (excellent) towards lower bit rate 32, 41.1, 48 MP3 192 – 224 kbps (very 1, 2 applications kHz good) 128 – 192 (good) Known as MPC, MPEGplus, Musepack 160 – 180 kbps - 2 MPEG+ or MP+, a derivative of MP2 Constant bitrate at Developed by Nippon TwinVQ 80, 96, 112, 128, --Telegraph and Telephone 160, 192 kbps Corporation Open and free codec project Vorbis 45 – 500 kbps - - from the Xiph.org Foundation Constant and Developed by Microsoft WMA variable bit rate -Multi support Audio Codec (2) Sampling Number of Codec bit rate Description frequency channels Voice (low bit rate, optimised for speech) Compressed pulse code G.711 64 kbps 8 kHz - modulation (PCM) Used in Voice over IP (VoIP) G.723.1 6.3, 5.3 kbps - - applications 16 – 40 kbps G.726 32 kbps (Commonly --- used) G.728 16 kbps - - - Mostly used in VoIP G.729 6.4, 8, 11.8 kbps - - applications Harmonic and Individual Lines HILN 6 – 16 kbps - - and Noise 4.75, 5.15, 5.90, AMR 6.70, 7,40, 7.95, - - Adaptive Multi-Rate, 10.2, 12.2 kbps Used in teleconference 8, 16, 32 Speex Variable - software, streaming, P2P and kHz audio processing applications Others (used for satellite radio and IBOC digital radio) Perceptual Audio Coding, an algorithm like MPEG’s MP3 PAC - - - standard, used by Sirius Satellite Radio.