1 Smoothing Variable-Bit Rate Video and Multiplexing in an Internetwork April 1, 2002 Ofer Hadar Communication Systems Engineering Dept., BGU URL: hadar

1

Smoothing Variable-Bit Rate Smoothing Variable-Bit Rate Video and Multiplexing in an Video and Multiplexing in an

Internetwork Internetwork April 1 , 2002April 1 , 2002

Ofer Hadar

Communication Systems Engineering Dept., BGU

URL: http://www.cse.bgu.ac.il/~hadar

Copyright @2001, O. Hadar

2

המחלקה - אוניברסיטת בן-גוריון בנגב (37111231 )רשתות תקשורת מולטימדיה להנדסת מערכות תקשורת

The Basic problemThe Basic problem

Network like predictable, “regular” traffic (CBR):

Can allocate resources (bandwidth, buffers,…) and commit to QoS

Allows for better pricing. Users like bursty information :

Data File transfer, fax, e-mail, telnet, web-browsing, etc.

Video streams are Variable Bit Rate (VBR) by nature.

3


OutlineOutline

Problem Background

Motivation for smoothing of pre-recorded video

The Piecewise Constant Rate Transmission and Transport (PCRTT) algorithm.

The e-PCRTT algorithm.

Multiplexing of smoothed video streams.

Conclusions and ongoing work.

4


Case in Point: MoviesCase in Point: Movies

Huge (and only?) bandwidth consumer

Without compression: Unthinkable (up to 1 Gbps for HDTV stream)

With compression: highly bursty

temporal and spatial information: frames vary in sizes, scenes vary in bandwidth rate

5


MPEG CompressionMPEG Compression::

Fixed GoP pattern such as IBBPBBP IBBPBBP I frames are JPEG encoded

B and P frames exploit temporal redundancy

I, P, B Frames

6


What to do ? (1)What to do ? (1)

Conservative rich: reserve peak required bandwidth.

Wasteful, costly:ratio of peak to average rate may be over 5:1.

Conservative poor:

compress to specified bandwidth

7


Peak Bandwidth reservationPeak Bandwidth reservation

0 200 400 600 800 1000 12000.8

1

1.2

1.4

1.6

1.8

2

2.2x 10

4

Reserved peak-rate Wasteful of Bandwidth

8


CBR Video EncodingCBR Video Encoding

b = target encoding rate

q(n) is a function of buffer contents

quantization becomes very coarse as buffer

contents approaches B

Why is it always blurry exactly when it starts getting interesting ?

Encoder Buffer

Digitizadvideo

B

q(n) = quantization scale

Xn

Storage

b/F bits per frame

9


What to do ? (2)What to do ? (2)

Practical solution: trade bandwidth for memory.

With large storage space: trickle the stream, playback from memory

need huge space how about live broadcast?

10


What to do ? (3) What to do ? (3) Smoothing of Pre-Recorded VideoSmoothing of Pre-Recorded Video

Solution : reduce burstiness by prefetching video frames into the client playback buffer

Emerging applications:

Distance learning

Movies, advertisements

Virtual reality

11


Network EnvironmentNetwork Environment

Server with pre-recorded video on large, fast disks

Network, perhaps with rate or delay guarantees

Client sites with buffer space for video playback

ClientSmoothing

BufferVideo File

Server

0 2 4 6 8 10 1.15 1.2 1.25 1.3 1.35 1.4 1.45 1.5 1.55 x 10 4

( e.g. set-top box)

0 2 4 6 8 10 1.15 1.2 1.25 1.3 1.35 1.4 1.45 1.5 1.55 x 10 4

Network

M onitor

12


Bandwidth Smoothing AlgorithmsBandwidth Smoothing Algorithms

Given the parameters:

Frame size {fi} for n frames

Client buffer size b And the constraints at the client buffer:

Avoid underflow Avoid overflow

Find a server transmission schedule consisting of:

Number of time intervals Transmission of video at rate rj during the interval j

Time intervals of length tj , in units of frame slots

k

iiunder fkF

0

k

iiover fbkF

0

nm

13


Burstiness of MPEG streamsBurstiness of MPEG streams

Integration

MPEG - Compressed video stream

B

B

P

BB

B

P

BB

II

I

Frame number

GOP

B

Bytes

14


Constructing a feasible rate-planConstructing a feasible rate-plan

Bandwidth changes

Overflow (Packets losses)

Underflow (Delay)

F_overF_under

b [buffer size]

b

start

end

Accumulative Bytes

Frame number

15


Existing Smoothing AlgorithmsExisting Smoothing Algorithms Critical bandwidth allocation [Feng95]

Minimum peak bandwidth Minimum number of bandwidth increases

Minimum changes bandwidth allocation [Feng95a]

Minimum peak bandwidth Minimum number of bandwidth changes

Minimum variability bandwidth allocation [Salehi96]

Minimum peak bandwidth Minimum variability of bandwidth allocations

Piecewise constant rate transmission [McManus96]

Bandwidth changes at periodic intervals Enhancement- Piecewise constant rate transmission [Hadar98]

Reducing the required client buffer

16


b

The PCRTT algorithmThe PCRTT algorithm

min_dif

max_difOffset

L

U

Accumulative bytes

Frame number / timet

difdifB min_max_min B=Buffer size

T

17


Description of construction theDescription of construction the e-PCRTT algorithm e-PCRTT algorithm

b(t)

F_under

F_over

b

I2

B=Buffer size

T

(Initial delay=b/2), I1 Time (in frames units)

Accumulative bytes

18


Motion JPEG trace StatisticsMotion JPEG trace Statistics (in Kb/Frame) (in Kb/Frame)

Video

Name

Big E.T

(100)

Home

Alone2

Honey, I

blew Up

the Kid

Hot

Shots 2

Junior Rookie

of the

Year

Seminar 1 Sister

Act

Mean

Rate

12.35 15.75 11.38 13.84 12.77 14.01 12.43 8.604 11.902

STD

Rate

3.58 3.29 2.48 3.18 3.24 3.19 2.73 0.59 2.61

Peak

Rate

23.48 30.55 22.01 23.29 29.93 25.12 27.88 10.98 24.91

The most burstiness trace The least burstiness trace

19


The influence of interval size on video rate-planThe influence of interval size on video rate-plan

0 500 1000 1500 2000 4000

5000

6000

7000

8000

9000

10000

11000

12000

13000

14000

Interval size = 100 [frames]Interval size = 500 [frames]Interval size = 1000 [frames]

Time (frame time units)

Bytes /frame

20


The impact of smoothing on the Marginal The impact of smoothing on the Marginal DistributionsDistributions

Unsmoothed

Smoothed:900 frames

Smoothed:10,000 frames

0 0.5 1 1.5 2 2.5

x 10 4

0

1000

2000

Rate [Bytes / frame]

No.

of

tran

smis

sion

Siz

es

0.8 1 1.2 1.4 1.6 1.8 2

x 10 4

0

20

40

1.1 1.2 1.3 1.4 1.5 1.6

x 10 4

0

5

10

No.

of

tran

smis

sion

Siz

esN

o.

of tr

ansm

issi

on S

izes



21


Bandwidth Fill Factor (Bandwidth Fill Factor (BFFBFF) criteria for network ) criteria for network utilizationutilization

ratePeak

rateAverage

ratePeak

rN

NratePeak

rBFF

N

ii

N

ii

_

_

_

1

_11

0 2000 4000 6000 8000 10000 12000 14000 0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

2.2 x 10

4

Smoothed transmission rate

Waste or allocate

elsewhere

Peak-rate

Time (frame units)

Byt

es/f

ram

e

Peak-rate

0 2000 4000 6000 8000 10000 12000 14000 0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

2.2 x 10

4

Video original bit rate

Waste or allocate elsewhere

Time (frame units)

Byt

es/f

ram

e

22


BFFBFF as function of the smoothing interval size (frames as function of the smoothing interval size (frames units), for 9 single streams and one multiplexed stream.units), for 9 single streams and one multiplexed stream.

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0.0E+00 2.0E+02 4.0E+02 6.0E+02 8.0E+02 1.0E+04

Smoothing interval size (Frames)

BF

F

Seq_1

Seq_2

Seq_3

Seq_4

Seq_5

Seq_6

Seq_7

Seq_8

Seq_9

Seq_10

Multiplexed stream

E.T

23


Individual SmoothingIndividual Smoothing

Individual smoothing is optimal in terms of Individual streams.

Individual smoothing implies smoothing each stream individually without considering other streams that are transmitted simultaneously.

Individual smoothing is not optimal in terms of a multiplexed group of streams.

24


Multiplexing of Smoothed Video streams according toMultiplexing of Smoothed Video streams according to e-PCRTT e-PCRTT

Smoothed video stream 2

Multiplexer...

Accumulative rate requirement (Bytes/Frame)

Rate requirement (Bytes/Frame)

Smoothed video stream 1

Smoothed video stream n Time (frame units)

Time (frame units)

25


Synchronized against Unsynchronized Multiple streams Synchronized against Unsynchronized Multiple streams (Total 5 video streams)(Total 5 video streams)

0 2000 4000 6000 8000 10000 12000 1.02

1.04

1.06

1.08

1.1

1.12

1.14

1.16

1.18 x 10

5

Synchronized multiple stream

Unsynchronized multiple stream

Time (in frames units)

Rate (Bytes/frame)

26


Rate histograms of multiplexed stream: Rate histograms of multiplexed stream: (a) Synchronized streams (b) Unsynchronized streams.(a) Synchronized streams (b) Unsynchronized streams.

5 6 7 8 9 10 11

x 10 4

0

50

100

150

200

5 6 7 8 9 10 11 12

x 10 4

0

100

200

300

400

Number of bandwidthchanges: 1,972

Max_rate=106,374. KB/frameStd. = 7,263 KB/frame

Max_rate=112,354 KB/frameStd. = 7,861 KB/frame

(a)

(b)

Number of bandwidthchanges: 5,918



No. o

f tr

ansm

issio

n S

izes

No. o

f tr

ansm

issio

n S

izes

27


Objectives for Objectives for Multiplexing algorithmsMultiplexing algorithms

Consider the interaction between all streams.

Provide each individual stream a valid transmission.

Provide each individual stream a near-to-optimal transmission schedule.

computation load should suite real-time purpose.

28


Different Schemes for Efficient MultiplexingDifferent Schemes for Efficient Multiplexing

Time shifting schemes (Admission control schemes).

Re-smoothing schemes.

Optimal smoothing with linear approximation.

29


Applying Admission Control Policy to E-PCRTT Smoothed Video Streams

In the initiation stream, the user negotiates an appropriate bandwidth rate-plan with the network.

For each video stream the network reserves a series of different CBRs over equal size time-intervals according to the e-PCRTT algorithm.

The following metrics are used to determine the optimal interval size and initiate transmission time:

The maximum BFF. The minimum rate variance. The minimum peak-rate of the multiplexed stream

30


Minimum variance of the Multiplexed streamMinimum variance of the Multiplexed stream

mn

diffunctionQ

blokblokdifn

nn

1_

1

0

5

10

15

20

25

bit

frame

reat program

31


0

5

10

15

20

25

1 2 3 4 5 6 7 8 9

0

5

10

15

20

25

1 2 3 4 5 6 7 8 9

Demonstration of the Admission control Demonstration of the Admission control processprocess

New request for a video stream

One interval shifting

32


Time allocation of 10 different multiplexing video streams using the BFF criteria

0 20 40 60 80 100 120 140 0

20

40

60

80

100

120 Actual Multiplexed Link Bandwidth

Time (Minutes)

33


BFF as a function of number of streams

1 2 3 4 5 6 7 8 9 10 0.82

0.84

0.86

0.88

0.9

0.92

0.94

0.96

0.98

1

B F

F

Number of streams

34


An example of multiplexing two video streams An example of multiplexing two video streams into a CBR channel before and after bandwidth into a CBR channel before and after bandwidth

smoothingsmoothing..

0 2 4 6 8 10 1

1.5

2

2.5

3

3.5

4 x 10 4

Combined smoothed streams Combined Unsmoothed streams

(1)

(2)

Peak -rate

35


The management process of bandwidth rate The management process of bandwidth rate reduction at the reduction at the j'thj'th interval interval

t

t

New plan Original plan

BW Network Peak-Rate

tj

Rate reduction

BWi

BW R

rI

36


M-EPCRTTM-EPCRTT Multiplexing of EPCRTT smoothed streamsMultiplexing of EPCRTT smoothed streams

All input streams are smoothed by the e-pcrtt algorithm using fixed-size intervals

Extreme peaks of the multiplexed stream exceeding the systems bandwidth are re-smoothed in order to achieve bandwidth reduction.

The re-smoothing is e-pcrtt oriented and provides each stream a valid, near-to-optimal transmission schedule

37


M-EPCRTT M-EPCRTT system’s inputsystem’s input

Non -Buffered Multiplexer

Smoothing

Smoothing

Smoothing

Total Bandwidth

Time

38




Smoothing

Smoothing

Smoothing

Total Bandwidth

Time

39




Smoothing

Smoothing

Smoothing

Total Bandwidth

Time

40




Smoothing

Smoothing

Smoothing

Total Bandwidth

Time

41




Smoothing

Smoothing

Smoothing

Total Bandwidth

Time

42



Time


Smoothing

Smoothing

Smoothing

Total Bandwidth

43



Time


Smoothing

Smoothing

Smoothing

Total Bandwidth

44



Time


Smoothing

Smoothing

Smoothing

Total Bandwidth

45



Time


Smoothing

Smoothing

Smoothing

Total Bandwidth

46



Time


Smoothing

Smoothing

Smoothing

Total Bandwidth

47



Time


Smoothing

Smoothing

Smoothing

Total Bandwidth

48



Time


Smoothing

Smoothing

Smoothing

Total Bandwidth

49


M-EPCRTT M-EPCRTT the multiplexed streamthe multiplexed stream

Time

Total Bandwidth

50



Time

Total Bandwidth

RR - The systems bandwidth.

The bandwidth of some intervals excesses the link’s bandwidth B.

51



Time

Total Bandwidth


MI

MI - multiplexing Interval.

The Multiplexed Streams is divided in to MI, each processed independently.

52



Time

Total Bandwidth


SI

SI - Individual Smoothing fixed size interval.

MI - multiplexing Interval.

MI

The MI is considerably larger than SI, (in simulation it was 45 times bigger).

53


M-EPCRTT M-EPCRTT iterative re-smoothingiterative re-smoothing

Time

Total Bandwidth

R

1) Find the Extreme Peak (will be denoted as Smoothing Interval SIj).

2) Select the stream (Si) which will enable a maximum bandwidth- reduction at the extreme peak.

SIj

54


M-EPCRTT M-EPCRTT iterative re-smoothingiterative re-smoothing

Time

The BFSM algorithm is implemented on the selected Individual stream in order to reduce its bandwidth at the extreme peak.

SIj

Si

55


M-EPCRTT M-EPCRTT BFSM algorithmBFSM algorithm

Time

Backward Forward Smoothing Multiplexing

Si

SIj

56



Time

The BFSM changes the transmission schedule of Si

by reducing the bite rate in SII and increasing it in the neighboring intervals.

Si

SIj

57



Time

In order to do so the area of neighboring intervals that would be changed should be determined.

Si

SIj

58



Time

We define the neighboring area between the nearest two local minimums.

Total Bandwidth

SIj

59



This is the E-PCRTT ‘Data Flow River’ of stream Si

60



The BFSM is derived from the E-PCRTT algorithm.

61


M-EPCRTTM-EPCRTT

BFSM algorithm

Re-smoothing

Iterated

RR

62


M-EPCRTT M-EPCRTT PerformancePerformance

0 5 10 15 20 25 30 35 40 452.6

2.8

3

3.2

3.4

3.6

3.8

4x 10

4Global Bandwidth Constraint:original "dotted", M-EPCRTT "solid"

Smoothing Intervals

Ban

dwid

th

63


M-EPCRTT M-EPCRTT PerformancePerformance

x 104

Iterations0 50 100 150 200 250 300

3.2

3.3

3.4

3.5

3.6

3.7

3.8

3.9

4Global Bandwidth Constraint:Maximum Bandwidth in every Iteration.

Ban

dwid

th

64


Optimal Multiplexing of Video StreamsOptimal Multiplexing of Video Streams

Assume m video streams. Denote the video streams by the index j = 1 , …, m.

Divide this stream into equal periods of length .

Let L j (t) be a piecewise linear approximation to L j (t) with

breakpoints at epochs .

Let the ith period correspond to the time interval: [ (i-1)t (i)t], i = 1,…,n .

Then the breakpoints of L j (t) , for the jth video stream, are

represented by the sequence of values : LI,J ,i = 0,…,n.

Construct a piecewise linear approximation of U j (t) with the

same breakpoints as in L(t) :U j (t) = L j (t) + bj

T

TnTiTTt ,...,,...,2,,0

65


The Linear programming solutionThe Linear programming solution

Buffer = B

Effective Buffer size

B’

Rate plane after Linear programming

66


Denote the values of U j (t) at each breakpoint as the

sequence: u i j ,i = 0,…,n .

where, u i j = l i j + bj

u i j u i+1 j

i-1 i i+1

ratel i j l i+1 j

yi j yi+1 j

67


Let such a schedule for the jth video stream be represented by the sequence:

S j = {yi j , yi+1 j ; i = 0,…,n } (1)

Such a schedule is said to be a feasible if: l i j <= yi j <= u i j ,i = 0,…,n (2)

Let r i j = the rate in segment i of the jth video stream.

where,

r i j = yi j - yi-1 j , i = 1,…,n (3)

Let the total rate for all video streams in period i be:

(4)

Let R denote the peak rate as the maximum rate over all n periods.

R = Max {r i ; i = 1,…,n } (5)

The Optimal Multiplexing Problem

The Optimal Multiplexing Problem is to find the collection of schedules {S j

; j = 1,…,m } such that the maximum rate is minimized, i. e.

Find Z = Min Max{r i ; i = 1,…,n } (6)

S j , j=1,…,m

n

jjii rr

1,

68


Small Example for Small Example for Multiplexing Solution from Multiplexing Solution from Linear ProgrammingLinear Programming

Buffer Size Fixed at B(j)= 5, for each Video Stream j = 1,2,3 . 4 time intervals L = 0 1 4 5 10

0 2 3 4 9 0 4 5 6 10

U =

5 6 9 10 15

5 7 8 9 14

5 9 10 11 15 The Optimal solution Transmission Schedule

Y =

5.0000 5.0000 8.0000 10.0000 10.0000

5.0000 5.0000 5.5000 5.5000 9.0000

5.0000 8.5000 8.5000 10.0000 10.0000

69


Total Rate = 3.5, 3.5, 3.5, 3.5 Total Rate = 3.5, 3.5, 3.5, 3.5 Optimal Rate = 3.5 (Buffer = 5)Optimal Rate = 3.5 (Buffer = 5)

1 1.5 2 2.5 3 3.5 4 4.5 50

5

10

15Stream for Video1

period epochsM

Byt

es

1 1.5 2 2.5 3 3.5 4 4.5 50

5

10

15Stream for Video2

period epochs

MB

ytes

1 1.5 2 2.5 3 3.5 4 4.5 50

5

10

15Stream for Video3

period epochs

MB

ytes

1 1.5 2 2.5 3 3.5 4 4.5 50

20

40

Period Epochs (Buffer =5 For Each Video Stream, Opt Multiplex Rate = 3.5)

Total All Video Streams

MB

ytes

70


Optimal Peak Rate vs Total Buffer SizeOptimal Peak Rate vs Total Buffer Size(Buffer = 5 for each Video Stream)(Buffer = 5 for each Video Stream)

0 5 10 15 20 25 30 35 400

2

4

6

8

10

12

14Optimal Peak Rate vs Total Buffer Size (Buffer =5 For Each Video Stream

Total Buffer Size , B

Opt

imal

Pea

k R

ate

, R

71


Total Rate = 7, 6, 8, 7 Total Rate = 7, 6, 8, 7 Optimal Rate = 8 (Buffer = 2)Optimal Rate = 8 (Buffer = 2)

1 1.5 2 2.5 3 3.5 4 4.5 50

5

10

Stream for Video1

period epochsM

Byt

es

1 1.5 2 2.5 3 3.5 4 4.5 50

5

10

Stream for Video2

period epochs

MB

ytes

1 1.5 2 2.5 3 3.5 4 4.5 50

5

10

Stream for Video3

period epochs

MB

ytes

1 1.5 2 2.5 3 3.5 4 4.5 50

20

Period Epochs (Buffer =2 For Each Video Stream, Opt Multiplex Rate = 8)

Total All Video Streams

MB

ytes

72


Zooming of Total Accumulative streamZooming of Total Accumulative stream

1 1.5 2 2.5 3 3.5 4 4.5 50

5

10

15

20

25

30

35

Period Epochs

TotalMultiplexed Stream(Buffer =2 For Each Video Stream,Opt Multiplex Rate = 8

MB

ytes

73


Zooming of Total Bit-rateZooming of Total Bit-rate

1 2 3 4 50

1

2

3

4

5

6

7

8

9

10

Periods (Buffer =2 For Each Video Stream, Opt Multiplex Rate = 8)

Total Rate - Multiplexed Stream

MB

ytes

74


Multiplexing ComparisonMultiplexing Comparison

Interval

PCRTT multiplexing without any manipulations

Multiplexing through Linear Programming

0 20 40 60 80 100 120 140 160 180 2003.5

4

4.5

5

5.5

6

6.5

7

7.5

8

8.5x 10

7R

ate(

Mbi

t/sec

)

Buffer size = 1 Mbytes

75




0 20 40 60 80 100 120 140 160 180 2003.5

4

4.5

5

5.5

6

6.5

7

7.5

8

8.5x 10

7

Interval

Rat

e(M

bit/s

ec)


76


7



0 20 40 60 80 100 120 140 160 180 2003.5

4

4.5

5

5.5

6

6.5

7

7.5

8

8.5x 10

Interval

Rat

e(M

bit/s

ec)


77


0 20 40 60 80 100 120 140 160 180 2003.5

4

4.5

5

5.5

6

6.5

7

7.5

8

8.5x 10

7

Interval

Rat

e(M

bit/s

ec)




78


0 20 40 60 80 100 120 140 160 180 2003.5

4

4.5

5

5.5

6

6.5

7

7.5

8

8.5x 10

7

Interval

Rat

e(M

bit/s

ec)




79


0 20 40 60 80 100 120 140 160 180 2003.5

4

4.5

5

5.5

6

6.5

7

7.5

8

8.5x 10

7

Interval

Rat

e(M

bit/s

ec)

Channel Bandwidth = C

Multiplexed Stream

RateonTransmissiunderareaTotal

BandwidthChannelaboveareaTotalPloss

80


0

0.05

0.1

0.15

0.2

0.25

0.3

Total Ploss

40 50 60 70 80 90 100Bandwidth(Mbit/sec)

P lo

ssPCRTT multiplexing without any manipulations



Rmax= 78 Mbit/s

Rmax= 65 Mbit/s

81


40 45 50 55 60 65 70 75 80 85 90

0

0.05

0.1

0.15

0.2

0.25

bandwidth(Mbit/sec)

P lo

ss

Rmax= 64 Mbit/s

Rmax= 78 Mbit/s




82


Total Ploss



40 45 50 55 60 65 70 75 80 85

0

0.05

0.1

0.15

0.2

0.25

0.3

bandwidth(Mbit/sec)

P lo

ss


Rmax= 78 Mbit/s

Rmax= 63 Mbit/s

83


Total Ploss

30 40 50 60 70 80

0

0.05

0.1

0.15

0.2

0.25

0.3

bandwidth(Mbit/sec)

P lo

ss

Rmax= 78 Mbit/s

Rmax= 62.5 Mbit/s




84


Block diagram for future research

VoD Disks

Video Server

Clients

Encoding + Streaming

Video Source

High Speed

Network

High Speed

Network

Video Rate Smoothing &Efficient schemes for Multiplexing

Stored Content

Live Video

R total_Max

)R3_Max, B3_max(

)R1_Max, B1_max(

)R2_Max, B2_max(

85


Ongoing WorkOngoing Work

Smoothing with Linear filtering Allows us to calculate analytically the rate histogram.

Smoothing after multiplexing Aggregated Smoothing.

Efficient smoothing algorithm for CBR service Deriving the optimum channel rate and initial play back delay

under the constraint of client buffer size. Optimization of the Multiplexing problem with different

constraints. Multiplexing of smoothed video streams in Video on Demand

System.

86


Future workFuture work

Construct an admission control suitable for real-time.

Implement other re-smoothing heuristics.

Comparing these algorithms with the optimal multiplexing algorithm.

Implementing a real VoD system which will include various multiplexing schemes.

Documents

1 Smoothing Variable-Bit Rate Video and Multiplexing in an Internetwork April 1, 2002 Ofer Hadar Communication Systems Engineering Dept., BGU URL: hadar