1. 1. Matterhorn Unconference 2014 Lets fix it in post! Ideas for automated post-recording video handling Stephen Marquard University of Cape Town 19 March 2014
2. 2. Why post-process video? A different approach to solving the blackboard challenge Improve video quality Close-ups More natural perspectives Avoid challenging lighting conditions (e.g. projection) Smooth motion (perfect knowledge of the future) Adjust for optimal colour / white balance / contrast Cost Multiple fixed HD IP cameras for half the cost of a PTZ camera / solution
3. 3. Cost + + < Bosch Dinion HD832 IP camera Vaddio ClearVIEW HD-USB IP camera
4. 4. The blackboard challenge How to get useful video where blackboard writing and diagrams are legible in large, wide venues
5. 5. Avoid sightline problems
6. 6. A real-time blackboard solution LectureSight: Direct a PTZ camera to follow the presenter, using real-time image analysis from an overview camera. https://opencast.jira.com/wi ki/display/LECTURESIGHT /LectureSight+Project+Ho me
7. 7. A post-processing presenter solution http://wiki.teltek.es/display/GaliTracker/GaliTracker+Home GaliTracker does cropping and zooming from a fixed HD image to give a presenter closeup
8. 8. Multiple fixed cameras 1
9. 9. Multiple fixed cameras 2
10. 10. Multiple fixed cameras 3
11. 11. Post-processing The capture agent records multiple camera streams (probably IP cameras): the mediapackage has 2, 3 or 4 presenter videos rather than 1. The camera streams are then post-processed to create a single presenter video (perhaps on the CA itself) Approaches: 1. Virtual panning (combine and crop) 2. Mixing (source selection)
12. 12. Virtual panning Left camera frame Centre camera frame Right camera frame Single panoramic image constructed from 3 fixed camera images Wide frame is cropped to position the presenter optimally (two-pass approach) Pros: smooth motion, optimal view. Cons: stitching images may be tricky, shifting perspectives.
13. 13. Mixing from multiple sources Image analysis and two-pass approach to select transition points between cameras (switch or cross-fade). Left camera Centre camera Right camera Selected camera
14. 14. Other post-processing ideas Improve colour, white balance and contrast dynamically or per region in the image. Compensate for the effect of projector image in the frame, and poor presenter lighting.
15. 15. Other post-processing ideas Improve image perspective and geometry Correct for fishbowl and other disturbing lens and camera positioning artefacts
16. 16. What next? Get involved! Good project topics for students. Share your ideas and possible contributions on the Matterhorn list(s).