Virtual Network Computer Recorder

1
Virtual Network Computer Recorder

• A Tool for Remote Learning

2
Group Members

• Marc Alban
• Jason Bonta
• Matt Jonker
• Greg Ose
• John Ruble
• Ashish Samuel

3
Overview

• Record all presentation material for distribution
  and review
• Application / video display
• Lecturer voice and audio
• Leverage existing technologies
• VNC (Virtual Network Computer)
• Audio compression (MP3 encoding/decoding)

4
Goals

• Seamlessly integrated and easy to use recording
  program
• Easy to distribute and efficiently sized session
  data file
• Portable client to playback recorded session

5
Existing Solutions

• vncrec
• Unix command line
• No audio
• vnc2swf
• Separate audio recording
• Exports to flash movie

6
Technical Implementation

• Microsoft C .Net
• Microsoft DirectX (DirectSound)
• Open Source Libraries
• LAME
• LibMAD
• ZLIB
• Open Source RealVNC Server

7
Recorder Architecture Overview
VNCR Recorder
Synchronizer
VNC Server
Interleaved Audio/Video File
Screen Updates
VNC Client
MP3 Data
Audio Recorder
8
Video Recording / Playback

• Capture
• Receives screen updates from RealVNC
• Zip raw bitmap data
• Add timestamps
• Playback
• Get screen update from file
• Unzip data and add to queue
• Draw screen updates to screen buffer

9
Audio Recording / Playback

• Capture
• Receive PCM data from DirectSound device buffer
• Convert from PCM to MP3 using LAME
• Playback
• Get chunk of MP3 data from file
• Decode MP3 data using LibMAD
• Put PCM data into DirectSound playback buffer

10
File Format

• Contains both audio and video data
• Synchronized using shared timestamps
• Video
• Recorded from local VNC server
• Lightweight screen encoding, uses GZIP
  compression
• Audio
• Captured using DirectSound input device
• Compressed using MP3 encoding
• Layered principle to promote modularity

11
File Format Diagram
12
Usage Examples

• Historical archive of lecture material
• Natural walkthrough and explanation of code
• Demonstration of the usage of any application
• Unlimited recording potential

13
Future Goals

• File editor
• Web browser plugin
• Streaming playback
• Fullscreen playback
• Integrated screen annotation

14
Example Demonstration

• Class lecture to teach basic networking