Upload
wade-mcintosh
View
120
Download
1
Embed Size (px)
DESCRIPTION
Audio Coding Standards. §2.3. 主要介绍. MPEG 及其相关的音频编码标准、算法原理 包括 : MPEG-1 Layer I, II & III , MPEG-2 AAC 以及与之相关的 Dolby AC-3 , MPEG-4 的 Natural Audio ,未来 MPEG 发展方向等。 国家 AVS (Audio Video Standard) 发展计划. 第二章 音频信息处理 ▪ 标准. Contents. 2.3.1 Overview of Audio Coding Standards - PowerPoint PPT Presentation
Citation preview
Audio Coding StandardsMPEGMPEG-1 Layer I, II & IIIMPEG-2 AACDolby AC-3MPEG-4Natural AudioMPEGAVS (Audio Video Standard)2.3
Contents 2.3.1 Overview of Audio Coding Standards 2.3.2 ITU-T Audio Coding Recommendations 2.3.3 Perceptual Audio Coding Basic 2.3.4 MPEG Audio Coding Systems 2.3.5 Dolby Audio Coding 2.3.6 China Audio Coding Initiatives 2.3.7 Next Step of Audio CodingReferences
ReferencesBasics about MPEG Perceptual Audio Codinghttp://www.iis.fraunhofer.de/amm/techinf/basics.html
MPEG _ Chinahttp://www.mpegchina.com.cn/index.htm
MPEG-4 Industry Forumhttp://www.m4if.org/
MPEG.ORGhttp://www.mpeg.org/MPEG/index.html
1. An Overview of Audio & Sound Coding Standards From Source Coding to Perceptual Coding Audio / Sound Coding Technologies Multimedia Communication Multimedia Framework
Audio Coding OverviewFrom source coding to perceptual codingPsychoacoustic ModelLow data rate, Hi-FiFrom signal to contentStructured Audio & Audio RetrievingFrom local application to global accessMPEG 21 perspectiveMultimedia FrameworkFrom stereo to surrounding multi-channelDolby AC-3 5.1 system & more
International ORG. / COM.International Telecommunication Unionhttp://www.itu.int/home/CCITTthe International Consultative Committee on Telephony and TelegraphyInternational Organization for Standardizationhttp://www.iso.org/International Electrotechnical Commissionhttp://www.iec.org/MPEGMoving Picture Experts Group http://mpeg.telecomitalialab.com/
Dolby Laboratories, Inc.http://www.dolby.com/ http://www.dolby.com.cn/
2. ITU Recommendations G.711-PCM G.721-32kbit/s G.722-64kbit/s(7KHz) CELP-16kbit/s ITU
Chronicle1972G.711 64kb/s A PCM 1984G.721 32kb/s ADPCM G.722 64kb/s ADPCM G.723.1 5.3kb/s6.3kb/s LSF G.726 16kb/s1990G.727 16-40kb/s ADPCM1992G.728 / G.729 16kb/s LD-CELP1988RPE-LTP 13kb/sGSM1989VSELP 6.7kb/s
ITU Recommendations
PCM64kb/sG.711ISDN4.04.5(A)(A)APCMDPCMADPCM32kb/sG.72 1SB-ADPCM64kb/sG.722G.726G.727LPC2.4kb/s2.53.5
ITU RecommendationsG.711PCM8000Hz8AA 13PCMA14PCM8G.721198664kbit/sAPCM32kbit/s ADPCMPCM
ITU RecommendationsADPCM/ APCMPCMPCM415(15)04 PCMAPCM(synchronous coding adjustment)()
3. Preliminary for Perceptual Audio Coding(Psychoacoustic Model)(Perceptual Sub-band Coding)Dolby AC-3/MPEG Audio Coding
Some Conceptions( dyn/cm2 )( W/cm2 )(dB)10-16 W/cm2 = 0 (dB)( phon ) ( sone ) = 0 () ( Hz ) Mel ()Mel = 1000 Log2(1+)
Perceptual Audio Coding (1)HzdB 1 kHz120dB()1202 kHz4 kHz
Perceptual Audio Coding (2) 20 Hz18000 Hz40 dB
Perceptual Audio Coding (3)(masking tone)(masked tone)
(Frequency Domain Masking)(Simultaneous Masking)
(Time Domain Masking)
Perceptual Audio Coding (3 cont.)
Perceptual Audio Coding (3 cont.)250 Hz1 kHz4 kHz8 kHz = 0.25, 1, 4 kHz
Perceptual Audio Coding (3 cont.)(Critical Band)20 Hz16 kHz24
Bark ()1 Bark = () < 500 Hz, 1 Bark /100 () > 500 Hz, 1Bark 9 + 4log( /1000)
Perceptual Audio Coding (3 cont.)
(pre-masking)(post-masking)
520 ms50200 ms
Perceptual Audio Coding (3 cont.)Audio Masking
4. MPEG Audio MPEG-1 Audio : Layer I, II &III MPEG-2 Audio : Back Compatible (BC)AAC : Advanced Audio Coding (Non BC) MPEG-4 Audio : Overview MPEG 21 : The Next Step of MPEGMoving Picture Experts Group Audio Coding Standards
About MPEGISOIEC WG111986MPEGMPEGMPEG MPEG-11992MPEG-2MPEG-319927(High-Definition TVHDTV)MPEG-4(1999)MPEG-5MPEG-6MPEG-7()
Chronicle of MPEG StandardsMPEG Audio Coding Standards199308 MPEG-1 ISO/IEC 11172199408 MPEG-2 ISO/IEC 13818199901 MPEG-4 ISO/IEC 14496 V1.0199912 MPEG-4 ISO/IEC 14496 V2.0199810 MPEG-7 200107 200109 200003 MPEG-21
Some ExplanationsMPEG-1 ISO/IEC 11172 MPEG-2 ISO/IEC 13818MPEG-4 ISO/IEC 14496 V1.0MPEG-4 ISO/IEC 14496 V2.0(video object)MPEG-7
Some Explanations (cont.)MPEG Audio(2 kHz5 kHz)()
Prices Aspects MPEG-LAMPEGMPEG-LAMPEGMPEG-LAWhyPrice ?MPEG 4
4. MPEG Audio MPEG-1 Audio : Layer I, II &III MPEG-2 Audio : Back Compatible MPEG-2 AAC : Advanced Audio Coding MPEG-4 Audio : OverviewMoving Picture Experts Group Audio Coding Standards
4. MPEG Audio MPEG-1 Audio : Layer I, II &III MPEG-2 Audio : Back CompatibleAAC : Advanced Audio Coding MPEG-4 Audio : OverviewMoving Picture Experts Group Audio Coding Standards
4. MPEG Audio MPEG-1 Audio : Layer I, II &III MPEG-2 Audio : Back CompatibleMPEG-2 AAC : Advanced Audio Coding MPEG-4 Audio : OverviewMoving Picture Experts Group Audio Coding Standards
4. MPEG Audio MPEG-1 Audio : Layer I, II &III MPEG-2 Audio :Back CompatibleAAC : Advanced Audio Coding MPEG-4 Audio : OverviewMoving Picture Experts Group Audio Coding Standards
MPEG-1 AudioAudio Coding Algorithms(sub-band codingSBC)SBCMPEGMPEG48 kHz16256 kb/s61 (40 kHz44.1 kHz)
MPEG-1 Audio (cont.)MPEG Audio ISO/IEC 11172-3
MPEG-1 Audio (cont.)/
Layer I, II & III
MPEG-1 Audio (cont.)CD*MUSICAM ( Masking pattern adapted Universal Sub-band Integrated Coding And Multiplexing ) **ASPEC ( Adaptive Spectral Perceptual Entropy Coding of high quality musical signal ) ()
MPEG-1 Audio (cont.)MPEG /
CRC MPEG
MPEG-1 Audio (cont.)(Layer III)
MPEG-1 Audio (cont.)-()(masking threshold)
(signal-to-mask ratioSMR)
(frame)
MPEG-1 Audio (cont.)32
MPEG-1 Audio (cont.)MPEG31231SBCSBCSBC (frame)Layer I 384 3212Layer II Layer III 1152
MPEG-1 Audio (cont.)
MPEG-1 Audio (cont.)Layer I1-DCT (discrete cosine transform)SMR 6(scale factor)SMR(bit allocation)
MPEG-1 Audio (cont.)Layer I(12) MUX
32
CRC16
4
6
MPEG-1 Audio (cont.)Layer II13111521 23 1(12)
MPEG-1 Audio (cont.)Layer III (Huffman)ASPEC (Audio Spectral Perceptual Entropy Encoding)OCF (Optimal Coding In The Frequency domain)12123(modified discrete cosine transformMDCT)12MDCT3
Layer IIIISO/MPEG Audio Layer III Coder / Decoder
MPEG-1 Audio (cont.)MPEG3
MPEG-2 Audio OverviewMPEG
MPEG-2 AudioMPEG-2 MultichannelMPEG-1 AudioMPEG-2 BC (Backward Compatible)MPEG-2 AAC (Advanced Audio Coding)MPEG-1MPEG-2 NBC (Non-Backward Compatible)
MPEG-2 Audio : BC
MPEG-2 BCISO/IEC 13818-3MPEG-2 BCMPEG-1 Audio (ISO/IEC 1117-3)-1, -2-316 kHz, 22.05 kHz24 kHz32384 kb/s8640 kb/s5.17.1Linear PCM(PCM)Dolby AC-3(Audio Code Number 3)
MPEG-2 BCMPEG-2 BC
MPEG-2 BC Multichannel5.13/2-LFE.1LFE3()2LFE (low frequency effects3Hz~120Hz) 7.15.1 5.1
MPEG-2 BC ISO/IEC 13818-3
MPEG AAC MPEG-2 AAC MPEG-2 AAC MPEG-2 AAC
MPEG-2 AACMPEG-2 AACMPEG-2MPEG-2 AACAAC8 kHz96 kHzAACAAC4816LFE (low frequency effects)16(overdub channel)(multilingual channel)16MPEG-2 AAC11:1(44.116 )/11=64 kb/s5320 kb/sMPEG2MPEG-2 AAC1MPEG370
MPEG-2 AAC MPEG-2 AACMPEG AudioAACAAC(advanced audio coding tools)(modular)(tool)AAC
(Main Profile)(Gain Control)AACAAC
(Low Complexity Profile)(temporal noise shapingTNS)(Scalable Sampling Rate Profile)TNS
MPEG-2 AAC (Gain control)PQF (polyphase quadrature filter)(gain detector)(gain modifier)4PQF(Filter Bank)MPEG-2 AACMDCTTDAC(time domain aliasing cancellation)
MDCTKBD (Kaiser-Bessel derived)(sine)MDCT
MDCT
n N i =
TNSTNSTNS(joint stereo coding)MPEG-2 AACM/S(Mid/Side encoding)/(Intensity /Coupling)M/SM/S(matrixed stereo coding)M/SM(middle)S(side)M/S-(sum-difference coding)/(intensity stereo coding)(channel coupling coding)(irrelevance)
(Prediction)(stationary)(Quantizer)(Noiseless coding)
MPEG-2 AAC
MPEG-4 AudioMPEG-4 Audio(parametric coding)(code excited linear predictiveCELP)/T / F (time / frequency)SA (structured audio)-TTS (text-to-speech)
MPEG-42 kb/s64 kb/s(natural audio)MPEG-48 kHz(speech)24 kb/s8 kHz16 kHz(audio)416 kb/s CELPCELP(code excited linear predictive)624 kb/s8 kHz16 kHzT/F-(time-to-frequencyT/F)(vector quantizationVQ)16 kb/s8 kHz
MPEG-4 Audio* UMTS (universal mobile telecommunication system)
MPEG-4TTSMIDI-Text-to-Speech
5. Dolby Audio CodingOverview of Dolby Audio Coding SystemAC-1 : Dolbys first digital coding systemAC-2 : 2-channel stereo systemDolby AC-3 : Multi-channel Digital Audio Compression System
Brief HistoryAC-1 (1987)Dolbys first digital coding systemSimple delta modulation based coding techniques4-2-4 multi-channel system, 2-1 bit-rate reductionAC-2 (1989)TDAC (Time Domain Aliasing Cancellation) Filter Bank based on MDCT/MDST2-channel stereo systemBit allocation based on Psychoacoustic ModelAC-2a : pre-echo control by block size adaptation
Brief HistoryAC-3 (1991~)TDAC Filter Bank based on MDCT5.1 multi-channel (320 kb/s) digital audioUSA HDTV Digital Audio Coding StandardFirst cinema demonstration : Star Trek VIChannel coupling techniques is applied to reduce bit-rate at high frequencies
AC-3 IntroductionInput Audio : 1 ~ 5.1 channels of source0.1 channel : low frequency (Subwoofer) signalsampling rate : 32 kHz, 44.1 kHz, 48kHzwindowing : 50% overlap/add Fielder windowBit Rate : 32 kb/s ~ 640 kb/sbandwidth reduction factor : 13.5uncompressed PCM sample : 6 channel * 48 kHz * 18 bits = 5.184 Mb/sstandard bit rate : 384 kb/s
AC-3 FeaturesAC-3 Encoder
AC-3 FeaturesAC-3 Decoder
AC-3 FeaturesBit-stream Syntax1 Frame represents 1536 PCM samples for all channels
1 Block represents 256 PCM for each channelSI=Sync. Info BSI=Bit-stream Info CRC for error correction Aux Data for private control
AC-3 FeaturesThe AC-3 Multi-channel CoderThe Conception of Multi-channel
6. Audio Coding Initiatives in China An Overview of Chinese AVS Project Audio Coding Quality Assessment Methods
China AVS ProjectAVS : audio video coding standard ()2002 621 Official Homepage : http://www.avs.org.cn
7. Next Step of Audio Coding Standardization MPEG 21:(Multimedia Framework)
Next StepMPEG-7MPEG-21MPEG62MPEG28JPEG2002102125
& MIDI MIDI FM, Wavetable MIDI MIDISMF/XMF/GM2.4
MIDIMusical Instrument Digital Interface (MIDI) (music synthesizers)(musical instruments) MIDI()MIDI MIDIMIDIMIDI
MIDI(cont.) () WAVEWAVEMIDI
WAVEMIDI WAVEMIDI
MIDIWAVE MIDI MIDIMic CD 5KB3.6MB 5242
MIDI(cont.)MIDI frequency modulation (FM) (Wavetable) MIDI
FMFM,, ()
FM(cont.)(Yamaha OPL-III)
FM1314ROMROMFM
FM 44.1 kHz16CD-DAROM
(cont.) ADSRFM
MIDIMIDIMIDIMIDIMIDIMIDI(local control)
MIDI(cont.)MIDI(bit stream)31.25 kbps10(181)(MIDI controller)(MIDI sequencer) MIDI MIDI3MIDIIN, OUTTHRU()MIDIMIDI OUTMIDI(MIDI sound generator)(MIDI sound module)IN(MIDI messages)
MIDI(cont.)Yamaha MIDI InstrumentsSimple for LaptopWith TX81Z Synthesizer Module
MIDI(cont.)MIDIMIDI(MIDI channel)16
MIDI(cont.)MIDI
MIDI(cont.)PCMIDIMIDIPCMIDIMIDIIN
MPC(Multimedia PC)(muti-timbral)(polyphonic)voicespatches()()(note)MPC(Base-level synthesizer)(Extended synthesizer)
MIDI(cont.) 33()63998
MIDIMIDI82(All MIDI status byte and data byte values are in hexadecimal )21n 0~F
Status ByteData BytesMessageBn 78 00 All Sound Off
MIDI(cont.) MIDI
MIDI MIDI MIDIMIDI note on MIDI note off MIDIMIDInote on MIDIMIDIMIDI(time-stamping)
MIDI SMF (Standard MIDI File) / XMF (eXtensible Music Format) MIDI(International MIDI Association)MIDI(Standard MIDI Files)MIDIMIDI MIDI(Standard MIDI File)3MIDIMIDIMIDI(tracks)MIDI0 (Format 0)MIDI(MIDI sequence data)MIDI1 (Format 1)MIDI2 (Format 2)
MIDIMIDI(International MIDI Association) MIDI(General MIDI Specification) MIDI(General MIDI Instruments)MIDI(General MIDI Sound Set)(patch map)MIDI(General MIDI Percussion Set)MIDI(General MIDI Performance)MIDI MIDIMIDI19111610
http://www.midi.org/http://crystal.apana.org.au/~ghansper/midi_introduction/
2MIDIMIDI