Media Compression- Video Coding Standards Summer 2018.ppt

1、Media Compression - Video Coding Standards Summer 2018,CMPT 365 Multimedia Systems,Video Coding Standards,H.264/AVC,Coding Rate and Standards,Mobile videophone,Videophone over PSTN,ISDN videophone,Digital TV,HDTV,Video CD,MPEG-4,MPEG-1,MPEG-2,H.261,H.263,Standardization Organizations,ITU-T VCEG (Vid

2、eo Coding Experts Group) standards for advanced moving image coding methods appropriate for conversational and non-conversational audio/visual applications. ISO/IEC MPEG (Moving Picture Experts Group) standards for compression and coding, decompression, processing, and coded representation of moving

3、 pictures, audio, and their combination Relation ITU-T H.262ISO/IEC 13818-2(mpeg2)Generic Coding of Moving Pictures and Associated Audio. ITU-T H.263ISO/IEC 14496-2(mpeg4),WG - work group SG sub groupISO/IEC JTC 1/SC 29/WG 1 Coding of Still PicturesISO/IEC JTC 1/SC 29/WG 11,Introduction,H.261 MPEG-1

4、 MPEG-2 H.263 MPEG-4 H.264,H.261,Earliest DCT-based video standard: 1990 ITU Recommendation for videoconferencing and videophones over ISDN Targeted bit rate: p x 64 kbps (p=1, , 30) Videophone: low rate, e.g., 64kbps Videoconferencing: high rate, e.g., 384kbps (p=6) Max: 1.92Mbps (p=30) Picture for

5、mat: CIF (Common Intermediate Format, 352 x 288) QCIF (Quarter CIF): 176 x 144. Max delay: 150 ms (for bidirectional interactivity) Sequential search Amenable to low-cost VLSI implementation No B mode,MPEG-1,Committee formed in 1988 Finalized in 1991 Used for VCD Random access, fast forward/reverse

6、search Delay: 1 sec (for unidirectional video access) 1/2-pixel ME/MC No deblocking filter B frames Software-only decoding is possible MPEG-1 Audio coding: 3 layers of encoding: Layer 1: 4 : 1 compression ratio with CD quality Layer 2: 6 : 1 to 8 : 1 Layer 3 (MP3): 10 : 1 to 12 : 1,MPEG-2,Completed

7、in 1994 Extension of MPEG-1 Standard for DVD, SDTV, HDTV Support interlaced inputs Support scalable coding Flexible frame size Low delay Support a wide range of applications Source format: 4:4:4:, 4:2:2, 4:2:0 1/2-pixel ME/MC (bilinear interpolation) B frames MPEG-2 Audio: Support 5.1 channels AAC:

8、30% fewer bits than MP3,Profiles and Levels,Defined to manage the large number of coding tools and the broad range of formats and bit rates supported Profiles and levels define a set of conformance points, each targeting a class applications Maximize interoperability and limiting the complexity Prof

9、ile: a subset of the entire bit stream syntax Levels: a specified set of constraints imposed on values of the syntax elements in the bit stream (maximum bit rate, buffer size, pic. resolution),MPEG-2 Levels,H.263,Derived from H.261 Intended for very low bit-rate application Better quality at 18-24kb

10、ps than H.261 at 64 kbps Used in MS NetMeeting, Messenger Can handle high resolution (up to 16CIF: 1408 x 1152) No loop filter 1/2-pixel ME/MC Optional coding modes (defined in 8 Annexes): Unrestricted motion vector (Annex D): MV can point outside of picture boundary by extrapolating the boundary pi

11、xels (repeat padding is usually used) MV range: -31.5, 31.5 Arithmetic coding Advanced prediction (Annex F): Overlapped block motion compensation 4MV: 1 for each 8x8 block,H.263+ and H.263+,H.263+: Second version of H.263 Some further optional features: Annex I to T. Annex J: in-loop deblocking filt

12、er H.263+: three more optional modes (2000) Annex V: Data partitioned slice mode For enhanced resilience to transmission error,MPEG-4,Based on H.263 A new concept rather than an improved algorithm Deal with a variety of multimedia contents: audio, visual , image, graphic. Part 2: Visual Based on H.2

13、63 Object-based coding Coding of animated objects Scalability: Fine Granular Scalability (FGS) Texture coding: wavelet-based Part 10: Advanced Video Coding H.264,Video Objects (VO),MPEG-4 treats a video sequence as a collection of video objects Each scene is decomposed into multiple objects The segm

14、entation method is not part of the standard Each object is specified by shape, motion, and texture. Natural visual Objects: Image, video, sprite (background) Synthetic visual object: Face and body 2-D mesh 3-D mesh The decoder can compose different scenes by using different number of decoded objects

15、,Scene Composition,The decoder can compose different scenes by using different number of decoded objects,MPEG-4 Structure,A/V object,Decoder,MUX,Compositor,Bitstream,Audio/Video scene,A/V object,Decoder,A/V object,Decoder,More MPEG-4 Example,Instead of ”frames”: Video Object Planes Shape Adaptive DC

16、T,Example,Problems, comments?,Example,Status,Microsoft, RealVideo, QuickTime, . But only recentagular frame based H.264 = MPEG-4 part 10 (2003),H.264,1998: Call for proposal for H.26L issued by ITU-T VCEG (Video Coding Expert Group) Objective: 50% bit rate savings compared to MPEG-2 High quality vid

17、eo at both low and high bit rates More error resilience tools Oct. 1999: First draft design Dec. 2001: VCEG and MPEG formed the Joint Video Team (JVT) Approved in 2003: ITU-T H.264 and ISO/IEC MPEG-4 Part 10 Advanced Video Coding (AVC),H. 264 Applications,Bit rate: 64kbps to 240Mbps Broadcast over c

18、able, satellite, DSL Interactive/serial storage on optical/magnetic devices, DVD Conversational services over network Video on demand, streaming media over network Multimedia messaging service over network,Three Profiles: Baseline, Main, and Extended 15 levels Four new profiles in Fidelity Range Ext

19、enstions (FRExt): High, High 10, High 4:2:2, High 4:4:4,H. 264 Slice coding,Slices can have different shapes and sizes Each slice is self-contained Can be decoded without knowing data other slices Useful for: Error resilience and concealment Parallel processing,Summary of Standards,SIF: Standard Int

20、erchange Format, 352x240 pixels at 30 Hz.,Beyond H.264,H.265 50% goal (bitrate reduction) Start from 2010 February 2012: Committee Draft (complete draft of standard) July 2012: Draft International Standard January 2013: Final Draft International Standard (ready to be ratified as a Standard) April 2013: Formal release Dec 2016: HEVC/H.265 version 4Google VP9Scalable video coding Multiview video/3D video 4K UHD,