kkushagra / qos

Quality of Service for MPEG Packets

QoS

Quality of Service for MPEG Packets

MPEG video frames contain 4 types of pictures, I, P, B and D. Loss of I and P pictures affect all other pictures within the same frame, causing more severe consequences than losing B or D picture packets. However, these priority levels of video picture packets are not known to the network forwarding engines. If congestion happen at the routers where there are video packets being forwarded, they will not honor the importance of I picture packets and drop them with the same rule as with P and B picture packets.

The aim of this project is to improve video quality by prioritizing I picture packets. The importance of I picture packets is made known to edge routers, so the edge routers will drop such packets with lower probability than other video packets when edge routers get congested. The rationale to enable this feature on edge routers but not core routers is that the core routers are busy forwarding packets all the time, so they can not do any extra work other than forwarding.

The overall architecture of the system we plan to work on is shown in the figure below. The video server generates video streams to the client. Edge router 1 is responsible for tagging I picture packets at the IP header. The core routers forward packets. Since the DSCP bits of I picture packets are marked, the edge router 2 gives them appropriate higher priority when the network is congested. The video client receives the videos and plays them.

System Test Topology

The dangling numbered texts are IP address assigned to an interface of a node, where a node can have multiple interfaces.

Marking I-MPEG packets flow logic

Testing Scenario

Configuration

The marking kernel module is loaded at edge router E1 and congestion is induced using a congestion inducing mechanism(iperf, packet generator etc.).

Package Information

config_scripts

This folder contains all the scripts required for configuration. <node>.sh scripts assign the IP address to each node, and install VLC package. <node_route>.sh scripts add all the routes and enable forwarding.

marking_module

The marking module contains the kernel module used for marking I packets.

test_video

There are two test MPEG videos that are provided to test system.

INSTALL

Details on setting up the system test enviroment.

Steps to stream video using VLC:

Step 1: Start VLC to recieve stream at Client

$ vlc rtp://@:<port_number_video>

Step 2: Start streaming at Server

$ vlc -vvv <filename> --sout '#rtp{dst=<destination_node>,port-video=<port>, port-audio=<port>,sout=keep}'

Thats it! You should be seeing the video stream on the client.

Testing Video Quality

Use any tool which supports SNR (Signal to Noise Ratio) or PSNR metrics to measure video quality. For example, MSU Video Quality Measurement Tool