Operating System: Chapter 7 - Multimedia Introduction to multimedia, Multimedia files, Video compression, Multimedia process scheduling, Multimedia file system paradigms, File placement, Caching, Disk scheduling for multimedia.
Trang 2Introduction to Multimedia (1)
Video On Demand: (a) ADSL vs. (b) cable
Trang 4Multimedia Files
A movie may consist of several files
Trang 7Video Encoding
Scanning Pattern for NTSC Video and Television
Trang 8Video Compression
The JPEG Standard (1)
RGB input data and block preparation
Trang 9The JPEG Standard (2)
One block of the Y matrix and the DCT
coefficients
Trang 10The JPEG Standard (3)
Computation of the quantized DCT coefficients
Trang 11The MPEG Standard (1)
Order of quantized values when transmitted
Trang 13The MPEG Standard (3)
Consecutive Video Frames
Trang 17Earliest Deadline First Scheduling (2)
Another example of realtime scheduling with RMS and EDF
Trang 18Multimedia File System Paradigms
Pull and Push Servers
Trang 20Near Video on Demand
New stream starting at regular intervals
Trang 21Buffering for Rewind
Trang 22Text Frame
Trang 23Two Alternative File Organization Strategies (1)
• Noncontiguous Movie Storage
(a) small disk blocks (b) large disk blocks
Trang 25Placing Files for Near Video on Demand
Optimal frame placement for near video on demand
Trang 27Placing Multiple files on a Single Disk (2)
• Organpipe distribution of files on server
– most popular movie in middle of disk– next most popular either on either side, etc.
Trang 32Dynamic Disk Scheduling
• ScanEDF algorithm
– uses deadlines & cylinder numbers for scheduling