50-qos video streaming

8/9/2019 50-QoS Video Streaming

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Quality of Service ofVideo Streaming

Mário Serafim NunesInstituto Superior Técnico

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QoS in Video Streaming

1 Theoretical conceptsQoS in Video Streaming

Heterogeneity in Video Streaming

Taxonomy of Congestion Control in Video Streaming

QoS mechanisms for Video Streaming

QoS metrics for Video streaming

2 R&D resultsOLYMPIC project architecture

Video QoS techniques developed in the project.

Evaluation of developed solutions.


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QoS inVideo Streaming

Bitrate:There is a need of a minimum bitrate toachieve an acceptable video quality

Delay:Real-time Video streaming requires boundeddelay and delay variation.

Losses:

Packet Loss Ratio ( PLR) should be kept belowa strict threshold to get an acceptable visualquality.

4

Heterogeneity

in Multicast Video Streaming

Network Heterogeneity

Networks have different resources (bitrate,buffer capacity, management policies).

Receiver HeterogeneityReceivers have different visual qualityrequirements (screen dimensions /spatialresolution, colours) and different processingcapabilities.

Consequently, different users could experience different

video quality reception.


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Network perspective: Network/Transport layers

Parameters: Packet delay, PLR (Packet Loss Ratio)

User perspective: Application (perceived quality)

Parameters: Video frame/VOP delay;PSNR (Peak Signal-to-Noise Ratio)

QoS Metrics for Video streaming

10

25520 logPSNR

MSE

= ⋅

( ) ( )2

2

, , f i j F i j MSE

N

− =

∑

6

Taxonomy of Congestion Control in

Multicast Video Streaming

Network based (N)

IntServ

DiffServ

Terminal based (A, T)

Transport layer perspective (T, T/A)

Rate control• Window-based control (TCP, DCCP-

CCID2)

• Rate-based control

- Source-based rate control (RTCP,DCCP-CCID3)

- Receiver-based rate control

- Hybrid rate control

Rate shaping

• Video frame Selective discard

• Dynamic rate shaping

Video Compression perspectiv (A)

Rate shaping

Rate Adaptive encoding

Application(A)

Transport

(T)

Selective Discard of

Video frames

Compression perspective

RTCP, UDP,

TCP,

DCCP

IntServ,

DiffServNetwork

(N)


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2 Research results

OLYMPIC project architecture

Core

Network

Access

Network

Media Encoder/

Media Server

PeripheralSAS

Clients

Core

SAS Unicast/

Multicast

Unicast/Multicast

Transmission of multimedia sport events (Audio/

Video) over IP in large scale, with large

heterogeneity of access network and terminals

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A) Selective Discard of Packets based on

DiffServ AF PHB (L3)

B) Selective Discard of Video Frames/VOP

based on RTCP reports (L4)

C) Selective Discard of Video Frames/VOP

based on TCP (L4)

D) Selective Discard of Video Frames/VOP

based on DCCP reports (L4)

Video Streaming QoS Techniques

developed in OLYMPIC project


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Video Streaming QoS Techniques

developed

A) Selective discard of Video Frames based on DiffServ

B) Selective discard of Video Frames based on RTCP

C) Selective discard of Video Frames based on TCP

D) Selective discard of Video Frames based on DCCP

A B C D

Discard layer Network(IP)

Application Application Transport

Transport

ProtocolUDP UDP TCP DCCP

Discard

pointRouter DS Server Server Server

Discard

based on

DSCP/AF RTCP Sender

buffer

Sender

buffer

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Solution A): Selective Discard ofvideo frames based in DiffServ

Application

layer

Transport

layer

Packet Marking QoS(MPEG4 DSCP)

UDP

Selective Discard of packets

(IP DiffServ)

Network

layer


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Architecture of solution A

Selective Discard based on DiffServ

Core

Network

Access

Network

Encoder/

Media Server

SAS

(QoS Marker)

Clientes

drop B

drop B+P

QoS

Marker

no drop

Unicast/

Multicast

Unicast/

Multicast

Tipo de Trama/

VOP MPEG4

Classe AF

I AF11 (low priority of discard)

P AF12 (medium priority of discard)

B AF13 (high priority of discard)

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PSNR – Peak Signal-to-Noise Ratio

AF PHB – Assured Forward Per Hop Behaviour

PSNR Results of solution A

(Selective Discard based on DiffServ)

0,0

5,0

10,0

15,0

20,0

25,0

30,0

0,0 5,0 10,0 15,0 20,0

PLR [%]

P S N R

[ d

B ]

Bes t effort Diffs erv AF


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Selective discard of Video frames/ MPEG4 VOP based

on PHB AF DiffServ presents good performance, it is

scalable and simple;

Mapping of MPEG4 video frames (I, B , P) in AF is not

an optimal solution, due to the dependency chain of

different MPEG4 frames (P depends on I; B depends

on I and P);

DiffServ only used in managed IP networks.

Conclusions of Solution A

(Selective Discard based on DiffServ)

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Solution B): Selective Discardof video frames based in RTCP

Application

layer

Transport

layer

MPEG4 QoS Classifier(MPEG4 QOS-type)

Selective Dropping

RTCP RR

UDP

IP(Best Effort)

Network

layer

Buffer

Congestion detected by reception of RTCP RR


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Block Diagram of solution B(Selective Discard based on RTCP)

Transport Layer

Application layer

Selective Discard Algorithm

Incoming Stream

RTCP feedback

from clients

Sent frames

Outgoing Stream

Discarded

frames

Index i GOV

→ I2 Pn Pn-1 … Pi Pi-1 … P3 P2 P1 I1 →

Discarded VOPs Sent VOPs first

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PSNR Results of solution B(Selective Discard based on RTCP)

0,0

5,0

10,0

15,0

20,0

25,0

30,0

0,0 5,0 10,0 15,0 20,0 25,0

PLR [%]

P S N R [

d B ]

Random discard Selective discard


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Random Discard vs Selective

discard with congestion of 35%

Random discard Selective discard

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Selective Discard based on RTCP presents high PSNR

gain in comparison with random discard

Allow dynamic adjust of discard level, optimizing the

available bandwidth;The delay of RTCP loss reports (typical 5s) can be a

problem in case the network presents frequent variations of

congestion level.

Conclusions of solution B(Selective Discard based on RTCP)


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Solution C: Selective Discard of videoframes based in TCP

Application

layer

Transport

layer

MPEG4 QoS Classifier(MPEG4 QOS-type)

Selective Dropping

TCP

IP

(Best Effort)

Network

layer

Buffer

Buffer

Congestion detected by the filling level of TCP Buffer

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Block Diagram of solution C(Selective Discard based on TCP)

IncomingStream

Application layer

Selective DiscardAlgorithm

+

Application Buffer

Frames sent

OutgoingStream

Transport Layer

Frames discarded

TCPbuffer

→ I9 Pn … P3 P2 P1 I8 Pn … P P2 P1 I Pn … P3 P2 P1 I →

Discard

Application Buffer at sender


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Movie average bitrate = 256 Kbps

TCP Buffer = 64 Kbyte -> 2 s

PSNR Results of solution C

(Selective Discard based on TCP)

0,0

5,0

10,0

15,0

20,0

25,0

30,0

0,0 5,0 10,0 15,0 20,0 25,0

PLR [%]

P S N R

[ d B ]

Ra nd om dis ca rd S el. Di sc ard TCP

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Selective Discard based on TCP presents

significant PSNR gains in comparison with

random discard;

This solution can be useful when reliability is a

requirement (p. ex. Transcoder)

As this solution is TCP based, it can have high

delay in case of congestion.

The bitrate could increase due to TCP packet

retransmission.

Conclusions of Solution C(Selective Discard based on TCP)


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Theoretical model (simulated) Model Implemented

Solution D): Selective Discard of

video frames based in DCCP

Application

layer

Transport

layer

MPEG4 QoS Classifier

(MPEG4 QoS-type)

Selective Dropping

DCCP

IP

(Best Effort)

Network

layer

Buffer

MPEG4 QoS Classifier

(MPEG4 QoS-type)

Selective Dropping

DCCP

IP

(Best Effort)

Buffer

UDP

DCCP: single buffer

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Selective Discard

Block based

Frame/VOP based

Algorithms activated by threshold:

Number of packets in DCCP queue

Time of existence of packet in DCCP queue

Algorithms developed for Solution D:

(Selective Discard based on DCCP)

→ I

9

P

n

… P

2

P

1

I

8

P

n

… P

2

P

1

I

7

P

n

… P

i

+

1

P

i

… P

2

P

1

I

6

→ DCCP

buffer

Discard


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PSNR Results for solution D


242526272829303132333435363738394041

0 5 10 15 20 25 30 35 40

Congestion Rate [%]

P S N R [

d B ]

DCCP, Queue Size=30pkts

DCCP+Block Disc ard, Lev el Threshold=30pkts

DCCP+Block Disc ard, Delay Threshold=1s

DCCP+VOP Discar d, Lev el Thres hold=30pkts

DCCP+VOP Discar d, Delay Threshold=1s

1314151617181920212223242526

0 5 10 15 20 25 30 35 40

Congestion Rate [%]

P S N R [

d B ]


DCCP+Block Discard Level Threshold=30pkts

DCCP+Block Discard, Delay Thres hold=1s

DCCP+VOP Discar d, Lev el Thres hold=30pkts

DCCP+VOP Discard, Delay Threshold=1s

StefanAkyio

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Results of Delay in Solution D

(Selective discard based on DCCP)

StefanAkyio

0

0.2

0.40.6

0.8

1

1.2

1.4

1.6

1.8

0 5 10 15 20 25 30 35 40

Congestion Rate [%]

A v e r a g e V O P

D e l a y [ s ]


DCCP+Block Discard, Level Thres hold=30pkts

DCCP+Block Discard, Delay Threshold=1s

DCCP+VOP Discar d, Lev el Threshold=30pkts

DCCP+VOP Discar d, Delay Threshold=1s

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

0 5 10 15 20 25 30 35 40

Congestion Rate [%]

A v e r a g

e V O P

D e l a y [ s ]


DCCP+Block Disc ard Level Threshold=30pkts

DCCP+Block Discard, Delay Thres hold=1s

DCCP+VOP Disc ard, Level Threshold=30pkts

DCCP+VOP Discard, Delay Threshold=1s


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Selective Discard based on DCCP presents high

PSNR gain in comparison with random discard;

This solution presents the lowest delay, due to the

single buffer at sender (at transport layer)

Presents higher discard flexibility since it allow

frame discard at transport layer.DCCP not deployed yet at large scale

Conclusions of Solution D


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A) Video Frame Selective Discard based on DiffServ

Simple, satisfactory results, but requires DiffServ.

B) Video Frame Selective Discard based on RTCP

Good results, problems with delay and report periodicity.

C) Video Frame Selective Discard based on TCP

Good results, works better with big buffers, but presents high end-to-end delay.

D) Video Frame Selective Discard based on DCCP

Solution that present best results due to optimization allowed byDCCP (best PSNR, lowest delay), but DCCP is not widely deployed.

Comparison of the different solutions

of Video Streaming QoS

50-qos video streaming

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