Multi-Threaded Video Rendering

COMP400 Project – 2006

Yohan Launay

Agenda

Basic System Description + Demo Quick Multi-threaded Programming Guide Video Channel Description Graphical Engine Description Results

Basic System Description

Client system connected to a video server MPEG4 Streaming Multivision System (1 screen – X cameras) Client: OpenGL graphical engine + GTK GUI Existing system audited, re-designed & optimized:

Optimization for multi-core systems 100% Thread safe design MT Programming Guide Performances Gain

Live Demo !Live Demo !

MT Programming Guide (1)

Modular System Mandatory 1 thread = 1 module (Core) Set of rules for safe MT programming (see

report) 1 mutex per core handled by the core itself

not externally Consequence: Extensive use of Controller &

Façade Pattern

Graphical Engine Architecture Overview

MT Programming Guide (2)

Mutex Class: Lock/Unlock (Existing) Guarantee exclusive access to resources

Synchronize Class (Optimization) Lock/Unlock – ExclusiveLock/ExclusiveUnlock Read/Write Access

AutoMutex Class (Ease of coding) Uses variable scope to lock/unlock Mutex

Video Channel Description

Connect to the video stream Fetch picture Ask for display:

Use of flags and IDs – Avoid memory copy Try to save space (pictures are big > 1MB)

Graphical Engine Description (1) OpenGL + GTK : need specific design Widget System

Widget (Abstract) WidgetContainer WidgetTexture

Chain of command: horizontal & vertical hierarchy

OpenGL: 1 Thread = 1 Rendering Context: Use of message pump / Command pattern

Widgets Architecture

Graphical Engine Description (2) Texture Register:

Avoid textures duplication in Graphical Card Manage texture loading and release Manage texture update

Extensive use of display lists Use of glTexSubImage: partial update On-demand display of channels

Video Rendering Process

Results

Results

Optimized for dual-core systems Unlimited number of cameras on the screen,

performances limited by the hardware. 400 FPS multivisions ! (hardware related) Future Plans:

OpenGL Game Mode (no more window + GTK)

Contact InformationYohan Launay

Mail : yohan.launay@gmail.com McGill : yohan.launay@mail.mcgill.ca MSDL: http://msdl.cs.mcgill.ca/people/yohan Past Work: http://hellaynnea.free.fr

Thank You For Your Attention!