7 MULTIMEDIA OPERATING SYSTEMS 7.1 INTRODUCTION TO MULTIMEDIA 7.2 MULTIMEDIA FILES 7.3 VIDEO COMPRESSION 7.4 MULTIMEDIA PROCESS SCHEDULING 7.5 MULTIMEDIA FILE SYSTEM PARADIGMS 7.6 FILE PLACEMENT 7.7 CACHING 7.8 DISK SCHEDULING FOR MULTIMEDIA 7.9 RESEARCH ON MULTIMEDIA 7.10 SUMMARY
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7MULTIMEDIA OPERATING SYSTEMS
7.1 INTRODUCTION TO MULTIMEDIA
7.2 MULTIMEDIA FILES
7.3 VIDEO COMPRESSION
7.4 MULTIMEDIA PROCESS SCHEDULING
7.5 MULTIMEDIA FILE SYSTEM PARADIGMS
7.6 FILE PLACEMENT
7.7 CACHING
7.8 DISK SCHEDULING FOR MULTIMEDIA
7.9 RESEARCH ON MULTIMEDIA
7.10 SUMMARY
Distribution network
Distribution network
Fiber
Video server
Video server
Copper twisted pair
Junction box
Junction box
House
Cable TV coaxial cable
Fiber
(a)
(b)
Fig. 7-1. Video on demand using different local distribution tech-nologies. (a) ADSL. (b) Cable TV.
Fast Ethernet 100222222222222222222222222222222EIDE disk 133222222222222222222222222222222ATM OC-3 network 156222222222222222222222222222222SCSI UltraWide disk 320222222222222222222222222222222IEEE 1394 (FireWire) 400222222222222222222222222222222Gigabit Ethernet 1000222222222222222222222222222222SCSI Ultra-160 disk 128022222222222222222222222222222211111111111
11111111111
11111111111
Fig. 7-2. Some data rates for multimedia and high-performanceI/O devices. Note that 1 Mbps is 106 bits/sec but 1 GB is 230
bytes.
1 432 5 6 7 8
Hello, Bob Hello, Alice Nice day Sure is How are you Great And you Good
Dag, Bob Dag, Alice Mooie dag Jazeker Hoe gaat het Prima En jij Goed
Video
English audio
French audio
German audio
English subtitles
Dutch subtitles
Fast forward
Fast backward
Frame
Fig. 7-3. A movie may consist of several files.
1.00
0.75
0.50
0.25
0
–0.25
–0.50
–0.75
–1.00
12 T
12 T
T T T
(a) (b) (c)
12 T
Fig. 7-4. (a) A sine wave. (b) Sampling the sine wave. (c) Quantiz-ing the samples to 4 bits.
Scan line
1
3
5
7
9
11
13
15
483
Tim
e
.
.
.
The next fieldstarts here
Scan line paintedon the screen
Horizontalretrace
Verticalretrace
Fig. 7-5. The scanning pattern used for NTSC video and televi-sion.
480
640
(a) (b) Q
RGB Y I640
480
240
320
240
1 Block
Block 4799
8-Bit pixel
24-Bit pixel
Fig. 7-6. (a) RGB input data. (b) After block preparation.
Y/I/
Q A
mpl
itude
DC
T
x Fx
y Fy
Fig. 7-7. (a) One block of the Y matrix. (b) The DCT coefficients.
150
92
52
12
4
2
1
0
80
75
38
8
3
2
1
0
40
36
26
6
2
1
0
0
14
10
8
4
0
1
0
0
4
6
7
2
0
0
0
0
2
1
4
1
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
DCT Coefficients
150
92
26
3
1
0
0
0
80
75
19
2
0
0
0
0
20
18
13
2
0
0
0
0
4
3
2
1
0
0
0
0
1
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Quantized coefficients
1
1
2
4
8
16
32
64
1
1
2
4
8
16
32
64
2
2
2
4
8
16
32
64
4
4
4
4
8
16
32
64
8
8
8
8
8
16
32
64
16
16
16
16
16
16
32
64
32
32
32
32
32
32
32
64
64
64
64
64
64
64
64
64
Quantization table
Fig. 7-8. Computation of the quantized DCT coefficients.
150
92
26
3
1
0
0
0
80
75
19
2
0
0
0
0
20
18
13
2
0
0
0
0
4
3
2
1
0
0
0
0
1
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Fig. 7-9. The order in which the quantized values are transmitted.
Fig. 7-10. Three consecutive video frames.
A1 A2 A3 A4 A5
B1 B2 B3 B4
Starting momentfor A1, B1, C1
Deadlinefor A1 Deadline for B1
Deadline for C1
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140
Time (msec)
A
B
C C2 C3C1
Fig. 7-11. Three periodic processes, each displaying a movie. Theframe rates and processing requirements per frame are differentfor each movie.
A1
A1
A1
B1
B1
A2
A2
A2
A3
A3 B3 A4
A3 B3 A4 A5 B4
A5 B4
A4 A5
B1 B2
B2
B2
B3 B4
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140
Time (msec)
A
B
C
EDF
RMS
C1
C1
C1
C2
C2
C2
C3
C3
C3
Fig. 7-12. An example of RMS and EDF real-time scheduling.
A1
A1
B1
B1
A1
A2
B2 B3A3 A4 A5 B4
A5
B1 B2
B2 Failed
A2
B3 B4
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140
Time (msec)
A
B
C
EDF
RMS
A2 A3 A4
C2 C3
C3
C1
C1 C2
Fig. 7-13. Another example of real-time scheduling with RMS andEDF.
Fig. 7-20. The curve gives Zipf’s law for N = 20. The squaresrepresent the populations of the 20 largest cities in the U.S., sortedon rank order (New York is 1, Los Angeles is 2, Chicago is 3,etc.).
Movie10
Movie8
Movie6
Movie4
Movie2
Movie1
Movie3
Movie5
Movie7
Movie9
Movie11
Cylinder
Freq
uenc
y of
use
Fig. 7-21. The organ-pipe distribution of files on a video server
A0A1A2A3A4A5A6A7
B0B1B2B3B4B5B6B7
C0C1C2C3C4C5C6C7
D0D1D2D3D4D5D6D7
(a)
A0A4B0B4C0C4D0D4
A1A5B1B5C1C5D1D5
A2A6B2B6C2C6D2D6
A3A7B3B7C3C7D3D7
(b)
A0A4B3B7C2C6D1D5
A1A5B0B4C3C7D2D6
A2A6B1B5C0C4D3D7
A3A7B2B6C1C5D0D4
(c)
A0A6B3B4C0C7D1D6
A2A5B1B7C2C6D2D5
A1A4B2B5C3C4D3D4
A3A7B0B6C1C5D0D7
(d)
1 2 3 4 1 2 3 4
1 2 3 4 1 2 3 4
Disk
Fig. 7-22. Four ways of organizing multimedia files over multipledisks. (a) No striping. (b) Same striping pattern for all files.(c) Staggered striping. (d) Random striping.
10 sec 1 min 2 min 3 min 4 min
0
1800
3600
5400
1800
3600
5400
7200
7200
User 1
0
User 2
Starts10 seclater
Time
0
1800
3600
5400
7200
User 1
User 2
Runs faster Normal speed
(a)
(b)
Runs slower Normal speed
5400
7200
1800
36000
Fig. 7-23. (a) Two users watching the same movie 10 sec out ofsync. (b) Merging the two streams into one.
1
701
2
92
3
281
4
130
5
326
6
410
7
160
8
466
9
204
10
524
92 130 160 204 281 326 410 466 524 701
Stream
Optimization algorithm
Order in which disk requests are processed
Buffer for odd framesBuffer for even frames
Block requested
Fig. 7-24. In one round, each movie asks for one frame.
Requests (sorted on deadline)
676
700 710 720 730 740 750
330
110 680 440 220 755 280 550 812 103
Deadline (msec)
Cylinder
Batch together
Fig. 7-25. The scan-EDF algorithm uses deadlines and cylindernumbers for scheduling.