1. Carnegie Mellon

2. Carnegie Mellon Video II

3. Carnegie Mellon Moving Picture Experts Group - MPEG The source code is not publicly available from the ISO

4. Carnegie Mellon MPEG-1 System Layer combines one or more data streams from the video and audio parts with timing information to form a single stream suited to digital storage or transmission.

5. Carnegie Mellon MPEG-1 Video Layer a coded representation that can be used for compressing video sequences - both 625-line and 525-lines - to bitrates around 1,5 Mbit/s. Developed to operate from storage media offering a continuous transfer rate of about 1,5 Mbit/s. Different techniques for video compression: –Select an appropriate spatial resolution for the signal. Use block-based motion compensation to reduce the temporal redundancy. Motion compensation is used for causal prediction of the current picture from a previous picture, for non-causal prediction of the current picture from a future picture, or for interpolative prediction from past and future pictures. –The difference signal, the prediction error, is further compressed using the discrete cosine transform (DCT) to remove spatial correlation and is then quantised. –Finally, the motion vectors are combined with the DCT information, and coded using variable length codes.

6. Carnegie Mellon MPEG-1 Video Layer

7. Carnegie Mellon MPEG-1 I,B,P Frames Choice of audio Encoding Picture size, bitrate is variable No closed-captions, etc. Group of Pictures one I frame in every group size 10-15 B and P are in random within GoP

8. Carnegie Mellon MPEG-1 Audio Layer Compress audio sequences in mono or stereo. Encoding creates a filtered and subsampled representation of the input audio stream. A psychoacoustic model creates data to control the quantiser and coding. The quantiser and coding block creates coding symbols from the mapped input samples. The block 'frame packing' assembles the actual bitstream from the output data of the other blocks and adds other information (e.g. error correction) if necessary.

9. Carnegie Mellon MPEG-1 Audio Layer

10. Carnegie Mellon MPEG-2 Digital Television (4 - 9 Mb/s) Satellite dishes, digital cable video Larger data size includes CC More complex encoding (“long time”) almost HDTV

11. Carnegie Mellon HDTV 2x horizontal and vertical resolution – SDTV: 480 line, 720 pixels per line, 29.97 frames per second x 16 bits/pixe l = 168 Mbits/sec uncompressed MPEG-1 brings this to 1.5Mbits/sec at VHS quality – HDTV: expanded to 1080 lines, 1920 pixels per line, 60 fps x 16 bits/pixel = 1990 Mbits/sec uncompressed MPEG-II like encoding, different audio encoding

12. Carnegie Mellon Video vs. computer (ROM) formats Single (R) and multiple (RAM) recordings possible Up to 17 GB of data 12 cm optical disc format data storage medium Replaces optical media such as the laserdisc audio CD, and CD-ROM. Will also replace VHS tape as a distribution format for movies MPEG-2 encoding Digital Video Disc (DVD)

13. Carnegie Mellon DVD Features Language choice (for automatic selection of video scenes, audio tracks, subtitle tracks, and menus). Optional Special effects playback: freeze, step, slow, fast, and scan (no reverse play or reverse step). Parental lock (for denying playback of discs or scenes with objectionable material). Optional Programmability (playback of selected sections in a desired sequence). Random play and repeat play. Digital audio output (PCM stereo and Dolby Digital). Compatibility with audio CDs Digital Zoom Six channel audio

14. Carnegie Mellon MPEG-4 MPEG 2 plus Interactive Graphics Applications Interactive multimedia (WWW), networked distribution

15. Carnegie Mellon MPEG-4 Bitrates from 32kb/s to 1Gb/s Several extension “profiles” Very high quality video Better compression than MPEG-1 Low delay audio and error resilience Support for “objects” Support for efficient streaming Not much industry activity at this point

16. Carnegie Mellon MPEG-4

17. Carnegie Mellon MPEG-4

18. Carnegie Mellon MPEG-7 (Due 2001) Data + Multimedia Content Description Scheme Description Definition Language Still in Committee Not data, but meta-data transmission and search Description Scheme + Content Description, e.g: Table of content Still Images Summaries links etc. How does the Description data get generated? How is it used?

19. Carnegie Mellon MPEG-7 (Due 2001)

20. Carnegie Mellon QuickTime An ISO standard for digital media Created by Apple Computer Inc., 1993 Audio, animation, video, and interactive capabilities for PC Allow integration of MPEG technology into QuickTime. QuickTime is available for MS Windows/NT as well QuickTime movies have file extension.qt and.mov. Description ftp://ftp.intel.com/pub/IAL/multimedia/indeo/utilities/smartv.exe converts quicktime to avi and back

21. Carnegie Mellon Video Players for your PC To play a movie on your computer, you need a multimedia player e.g. an MPEG player or QuickTime player. These players are also called decoders because they decode the MPEG or QuickTime, RealNetworks, etc. compressed codes. Some software allow you to both encode and decode multimedia files, e.g. to make and play the files. –You’ll use both for your digital video homework assignment. Some software only allow you to play back multimedia files.

22. Carnegie Mellon Video Quality Ram 200kbps Ram 56kbps 160x120 window (200kbps) 240x180 window (200kbps) 320x240 window (200kbps)

23. Carnegie Mellon References MPEG-1 System Layer MPEG-1 Video Layer MPEG-1 Audio LayerMPEG-1 Audio Layer Definition of Video Terms

24. Carnegie Mellon Encoding Video (Homework #5)

25. Carnegie Mellon In WeH5304 Encoder0.inf.cs.cmu.edu Login: mmCourse Password: MultiMedia C:\Program Files\Optibase\Mpeg Composer\Composer.exe Power on Sony SVHS player (and TV Monitor above it) Insert your video and pause it Encoding Video (Homework)

26. Carnegie Mellon VHS not turned on and stopped (no signal to encoder) Encoder is working correctly

27. Carnegie Mellon Recording Set a file name (select target file) –default is c:\Program Files\Optibase\MPEG Composer\Test.mpg

28. Carnegie Mellon Recording Hit the red button –yellow light comes on –Stop recording (right square button) when video is done

29. Carnegie Mellon After you’re done encoding Double check that there is audio and video! Copy/ftp the file somewhere else! Record the next clip

30. Carnegie Mellon Encoding Alternative MPEG.inf.cs.cmu.edu login: mmCoursepassword: MultiMedia C:\MPSUITE\mpeglab.exe set output file, turn on VCR + put tape in, press red record button + press square stop button when done

31. Carnegie Mellon After you’re done encoding Double check that there is audio and video! Copy/ftp the file somewhere else! Record the next clip

32. Carnegie Mellon Transcoding Video from MPEG to RM Smith1.inf.cs.cmu.edu in WeH5304 login: mmCourse password: MultiMedia C:\Program Files\Real\RealProducer\realprod.exe

33. Carnegie Mellon Using Real Producer Set input and output file names

34. Carnegie Mellon Using Real Producer To transcode from file (mpg) to file (rm) –Add Title, Author, Copyright –Select Audio and Video Format –Select Target Viewer Network –Select single rate format –Start

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36. Carnegie Mellon Create a web page Read the instructions Pretty much idiot proof Copy your web page to somewhere else! Leave the machine without new ‘defaults’ or new settings or leftover video clips!

37. Carnegie Mellon Video II That’s all for today

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