V ENUS INTERNATIONAL COLLEGE OF TECHNOLOGY Guided by : Rinkal mam

P REPARED BY :  Liza Vyas ( )  Bhavya Tiwari ( )  Heena Parmar ( )  Krishna Pancholi ( )  Varsha Shukla ( )

V IDEO C OMPRESSION & MPEG F ORMATE

V IDEO C OMPRESSION Once video is in digital format, it makes sense to compress it Similarly to image compression, we want to store video data as efficiently as possible Again, we want to both maximize quality and minimize storage space and processing resources This time, we can exploit correlation in both space and time domains

MPEG (M OVING P ICTURES E XPERT G ROUP ) Committee of experts that develops video encoding standards Until recently, was the only game in town (still the most popular, by far) Suitable for wide range of videos Low resolution to high resolution Slow movement to fast action Can be implemented either in software or hardware

E VOLUTION OF MPEG MPEG-1 Initial audio/video compression standard Used by VCD’s MP3 = MPEG-1 audio layer 3 Target of 1.5 Mb/s bitrate at 352x240 resolution Only supports progressive pictures

E VOLUTION OF MPEG MPEG-2 Current de facto standard, widely used in DVD and Digital TV Ubiquity in hardware implies that it will be here for a long time Transition to HDTV has taken over 10 years and is not finished yet Different profiles and levels allow for quality control

E VOLUTION OF MPEG MPEG-3 Originally developed for HDTV, but abandoned when MPEG-2 was determined to be sufficient MPEG-4 Includes support for AV “objects”, 3D content, low bit-rate encoding, and DRM In practice, provides equal quality to MPEG-2 at a lower bit-rate, but often fails to deliver outright better quality MPEG-4 Part 10 is H.264, which is used in HD-DVD and Blu-Ray

MPEG: V IDEO E NCODING Pre processing Frame Memory + - DCT Motion Compensation Motion Estimation Frame Memory + IDCT Quantizer (Q) Regulator VLC Encoder Buffer Q -1 Output Input Predictive frame Motion vectors

GOP (G ROUP OF P ICTURES ) GOP is a set of consecutive frames that can be decoded without any other reference frames Usually 12 or 15 frames Transmitted sequence is not the same as displayed sequence Random access to middle of stream – Start with I frame

S COPE OF VIDEO CODING STANDARDIZATION Pre-ProcessingEncoding Decoding Post-Processing & Error recovery Source Destination Scope of Standard

R UN -L ENGTH C ODING Zigzag Scan

Four Compression Modes I frame : Intra-frame JPEG-like coding P frame : forward Prediction from previous frames B frame : forward, backward or bi-directional Prediction D frame : contain only the DC component of each block IPPBBBBBB GOP

MPEG-I VS. H.261 H.261MPEG-1 Sequential access Random access One basic frame rate Flexible frame rate CIF and QCIF images only Flexiable image size I and P frames only I, P and B frames MC over 1 frame MC over 1 or more frames Integer-pel MV accuracy Half-pel MV accuracy Spatial filtering in the loop No filter Variable threshold+uniform quantization Quantization matrix No GOP structure GOP structure GOB structure Slice structure

A PPLICATIONS ON H.264/AVC STANDARD Broadcast over cable, satellite, cable modem, DSL, terrestrial, etc. Interactive or serial storage on optical and magnetic devices, DVD, etc. Conversational services over ISDN, Ethernet, LAN, DSL, wireless and mobile networks, modems, etc. or mixtures of these. Video-on-demand or multimedia streaming services over ISDN, cable modem, DSL, LAN, wireless networks, etc. Multimedia messaging services (MMS) over ISDN, DSL, LAN, wireless and mobile networks, etc.

Thank You …