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 !

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

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 Information Yohan Launay Mail : McGill : MSDL: Past Work: Thank You For Your Attention!