報告人：林祐沁 學生指導教授：童曉儒 老師

March 2, 2009

2

•Wireless Video Surveillance Server Based on CDMA1x and H.264

3

Outline

•Introduction

•System Structure

•H.264 Coding Implementing

•Video Qos Control Strategies In Wireless Environment

•Conclusions

4

Introduction

• Increasing requirement for securing and network technology.• Video surveillance based on IP has developed.

• Remote video surveillance：• Wire -> Wireless(CDMA1x)

• This paper presents ：• A realization scheme of wireless video surveillance

server based on CDMA1x and H.264.

• Discusses key technique and wireless video quality of service(QoS) control strategies.

5

System Structure

• embedded hardware platform and embedded Linux operation system.

• H.264 video compression standard.

• local-storage function, keep important information in breaking off.

• GPS orientation function, orientation and track of the mobile surveillance platform.

• some strategies, rate control, congestion control, error control.

6

Video Qos Control Strategies In Wireless Environment(1/2)

• Media stream requirement of network bandwidth, delay, jitter, packet loss rate.

• There are two thoughts ：• Make the network have the ability to guarantee QoS.

- needs to reconstruct the core equipments

• Improves the transmission quality by the control function of the terminal system.

- don’t change the network existing

7

Video Qos Control Strategies In Wireless Environment(2/2)

•End-to-end media stream QoS control structure ：

8

Congestion Control of Wireless Video

•The most equation-based congestion control algorithm is TCP Friendly Rate Control(TFRC).• packet loss is found, then reduce the

transmit rate.

•This assumption is tenable in Wire environment.• the bit error rate of the wired channel is

very low.

9

Congestion Control of Wireless Video

•Adopts equation-based congestion control algorithm for wireless channel.

•Uses Markov mode of two states ：wireless channel and wired channe.

10

Rate Control of Wireless Video

•Congestion control mechanism requires the transmit terminal adjust the transmit rate.

•rate control recede the quality of media.• size of the picture, distortion, frame rate

11

Rate Control of Wireless Video

•The typical way is to control the bit number of coding output by adjusting the filling of coding buffer.

12

Error Control of Wireless Video

•wireless channel has high bit error rate.• Error-toleration and correction

•video communication has a strict requirement for delay• The common data service reliable protocol

(such as TCP).

- FEC adds redundancy information to make get back correct.

13

Error Control of Wireless Video

• This paper not only uses FEC but also adopts delay-bound retransmission.

• If ,requests transmitter to retransmit N• Tc： the present time.

• RTT ： estimate trip time.

• Ds： time of tolerate estimate error, response of transmitter and decoding delay of receiver.

• Td(N) is the deadline of packet arriving.

14

Performance Analysis

15

•Advanced wireless Multiuser Video Streaming Using The Scalable Video Coding Extensions Of H.264/Mpeg4-avc

16

Outline

• Introduction

• Scalable Video Coding And Media Adaptation

• Radio Link Buffer Management For Scalable Video Streams

• Simulation And Results

• Conclusion

17

Introduction

•Wireless video streaming services, the need for higher capacity radio access networks.

•One possible approach is the definition of quality-of-service (QoS) attributes for each media flow.• admission control

• resource reservation

18

Introduction

•This paper presents ：• Dynamic sharing of the resources by SVC.

• Appropriate radio link buffer managementfor multiuser streaming services.

19

Scalable Video Coding AndMedia Adaptation

•Scalable Video Coding (SVC)• An extension of H.264/MPEG4-AVC.

• Scalability function allows removal of parts of the bitstream.

• Reduced temporal, SNR, or spatial resolution.

• Bitstream consists of a base layer and one or several enhancement layers.

20

Scalable Video Coding

•Temporal scalability• often based on a temporal decomposition

using hierarchical B pictures.

21

Scalable Video Coding

•Spatial scalability• motion-compensated prediction (MCP)

structures for each layer.

• achieved different encoder quality ： QCIF, CIF, and 4CIF

•SNR scalability• progressive refinement (PR) coding.

• contains refinements for the residual (texture) data.

22

Adaptation and Transport of SVC

•hierarchical B pictures and the PR coding approach are combined.

•The priority scale is starting from the lowest temporal layer.

•PR fragments is next lower importance

23

Adaptation and Transport of SVC

•Rate adaptation dropping order• Drop PR fragments of the highest temporal

level present.

• Drop base layer of highest temporal level present.

24

SVC NAL Unit header

• Extension of the H.264/MPEG4-AVC NAL unit.

• Byte 1 ： Forbidden Field(F), NAL Unit Reference Indicator(NRI), NAL Unit Type.

• Byte 2 ： signals Simple Priority ID, discardable flag (D), Extended Bit (E).

• Byte 3 ： Temporal,Spatial, and Quality Level.

25

Priority Labeling

•H.264/MPEG4-AVC only offer temporal scalability.

•SVC bitstreams offer a wide range of options for rate adaptation.

•Define the following intermediate priority value

26

Priority Labeling

•Existing solutions for temporal scalability,

•Final priority value for each packet is defined

27

Radio Link Buffer Management For Scalable Video Streams

•Wireless Multiuser Streaming Environment• M users in the coverage area.

• NAL units encapsulated in RTP packets.

• Drop Strategy• If there are still packets which contain PR

fragments(i.e. with pr <= 254) in the buffer.

• base layer fragments with no further dependencies (i.e. with pr = 255)

• base layer fragments (i.e. with pr > 254)

28

Simulation And Results

29

Simulation And Results

30

Simulation And Results

31

Simulation And Results