Audio Codec
Audio Codec
Audio Codec
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<strong>Codec</strong>bit rateGeneral (medium to high bit rate)640 kbps (max.)448 kbps (DVD,AC-3 Digital cable TV)384 kbps (ATSC)<strong>Audio</strong> <strong>Codec</strong> (1)SamplingfrequencyNumber ofchannels- MultiDescriptionBelonging to Dolby Digital,supporting multi-channelaudio, used on DVDPulse-code modulation, digitalrepresentation of an analoguesignal by sampling thePCMVariedmagnitude of the signal at- Up to 864 kbps (DS0)uniform intervals, used indigital telephone systems anddigital audio in computers andCDsAAC - 8 – 96 kHz - Advanced <strong>Audio</strong> Coding,ATRAC48, 64, 66, 132, 256kbps- -Adaptive Transform AcousticCoding, developed by Sony,used to store information onMinidisc,Digital Theatre System, used768 – 1536 kbps (6-DTS- Multi for in-movie sound on film andchannel)on DVDMP1 384 kbps Varied 1, 2 Lowest encoder complexityMP2MP3256 – 384 kbps(excellent)224 – 256 kbps (verygood)192 – 224 kbps(good)224 – 320 kbps(excellent)192 – 224 kbps (verygood)128 – 192 (good)Varied 1, 232, 41.1, 48kHzMusepack 160 – 180 kbps - 2TwinVQConstant bitrate at80, 96, 112, 128,160, 192 kbps- -Vorbis 45 – 500 kbps - -WMAConstant andvariable bit ratesupport1, 2- MultiMore complex encoder anddecoder, able to remove moreof the signal redundancy andto apply the psychoacousticthreshold more efficientlyMore complex, directedtowards lower bit rateapplicationsKnown as MPC, MPEGplus,MPEG+ or MP+, a derivativeof MP2Developed by NipponTelegraph and TelephoneCorporationOpen and free codec projectfrom the Xiph.org FoundationDeveloped by Microsoft
<strong>Audio</strong> <strong>Codec</strong> (2)Sampling<strong>Codec</strong>bit ratefrequencyVoice (low bit rate, optimised for speech)Number ofchannelsG.711 64 kbps 8 kHz -G.723.1 6.3, 5.3 kbps - -G.72616 – 40 kbps32 kbps (Commonlyused)- - -DescriptionCompressed pulse codemodulation (PCM)Used in Voice over IP (VoIP)applicationsG.728 16 kbps - - -G.729 6.4, 8, 11.8 kbps - -Mostly used in VoIPapplicationsHILN 6 – 16 kbps - -AMRSpeex4.75, 5.15, 5.90,6.70, 7,40, 7.95,10.2, 12.2 kbpsVariableHarmonic and Individual Linesand Noise- - Adaptive Multi-Rate,8, 16, 32kHzOthers (used for satellite radio and IBOC digital radio)PAC - - --Used in teleconferencesoftware, streaming, P2P andaudio processing applicationsPerceptual <strong>Audio</strong> Coding, analgorithm like MPEG’s MP3standard, used by SiriusSatellite Radio