General Principles of Intellectual Property: Concepts of Intellectual Proper...
Kbk436 Sistem Operasi Lanjut Lecture02
1. Lecture 2
Multimedia File System
2.1. Multimedia file system paradigms
2.2. File placement
2.3. Caching
2.4. Disk scheduling for multimedia
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2. Multimedia File System Paradigms
Pull and Push Servers
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3. VCR Control Functions
• Rewind is simple
– set next frame to zero
• Fast forward/backward are trickier
– compression makes rapid motion complicated
– special file containg e.g. every 10th frame
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4. Near Video on Demand
New streamhttp://fasilkom.narotama.ac.id/ intervals
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starting at regular
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5. Near Video on Demand with VCR Functions
Buffering for Rewind
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6. File Placement
Frame 1 Frame 2 Frame 3
Audio Text
Frame Frame
Placing a File on a Single Disk
• Interleaving
– Video, audio, text in single contiguous file per movie
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7. Two Alternative File Organization Strategies (1)
• Noncontiguous Movie Storage
(a) small disk blocks
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(b) large disk blocks 7
8. Two Alternative File Organization Strategies (2)
Trade-offs between small, large blocks
1. Frame index
- heavier RAM usage during movie play
- little disk wastage
• Block index (no splitting frames over blocks)
- low RAM usage
- major disk wastage
• Block index (splitting frames over blocks allowed)
- low RAM usage
- no disk wastage
- extra seeks
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9. Placing Files for Near Video on Demand
Optimal frame placement for near video on demand
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10. Placing Multiple files on a Single Disk (1)
• Zipf's law for N=20
• Squares for 20 largest cities in US
– sorted on rank order
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11. Placing Multiple files on a Single Disk (2)
• Organ-pipe distribution of files on server
– most popular movie in middle of disk
Sistem– next most popular either on either side, etc.
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12. Placing Files on Multiple Disks
Organize multimedia files on multiple disks
(a) No striping
(b) Same striping pattern for all files
(c) Staggered striping
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(d) Random striping 12
13. Caching
Block Caching
(a) Two users, same movie 10 sec out of sync
(b) Merging two streams into one
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14. File Caching
• Most movies stored on DVD or tape
– copy to disk when needed
– results in large startup time
– keep most popular movies on disk
• Can keep first few min. of all movies on disk
– start movie from this while remainder is fetched
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15. Disk Scheduling for Multimedia
Stream
Order in which disk requests are processed
Static Disk Scheduling
• In one round, each movie asks for one frame
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16. Dynamic Disk Scheduling
• Scan-EDF algorithm
– uses deadlines & cylinder numbers for scheduling
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