I'm trying to figure out the best approach to display a video on a GL texture while preserving the transparency of the alpha channel.
Information about video as GL texture is here: Is it possible using video as texture for GL in iOS? and iOS4: how do I use video file as an OpenGL texture?.
Using ffmpeg to help with alpha transparency, but not app store friendly is here:
iPhone: Display a semi-transparent video on top of a UIView?
The video source would be filmed in front of a green screen for chroma keying. The video could be untouched to leave the green screen or processed in a video editing suite and exported to Quicktime Animation or Apple Pro Res 4444 with Alpha.
There are multiple approaches that I think could potentially work, but I haven't found a full solution.
- Realtime threshold processing of the video looking for green to remove
- Figure out how to use the above mentioned Quicktime codecs to preserve the alpha channel
- Blending two videos together: 1) Main video with RGB 2) separate video with alpha mask
I would love to get your thoughts on the best approach for iOS and OpenGL ES 2.0