Combine 4 separate component R G B A in one texture
Here's a short description of my problem :
I'm developing a viewer for video-sequences. I use a scan-line based approach with concurrent computation (fetching) for each row. Every row I get is separated in severals buffer (Channels) , namely R,G,B,A.
So imagine the problem as: I want to combine all my channels into one texture. I have thought of doing it my-self, by allocating a temporary buffer in which I can upload the severals component, and give it to openGL with glTexSubImage2D(...), but the solution is very expensive...especially for image streaming!
Then I thought of multi-texturing: in short, make a separate texture (GL_LUMINANCE?) for every channel, and then combine it with a GLSL shader. I think this could work, unfortunately I have no experience in multi-texturing. Could somebody give me a link to a complete tutorial for multi-texturing please?
The last thing I could dig out of the internet is using a FBO, with a buffer texture. In the buffer texture, use a buffer object with several indexes. But I couldn't get much more details about indexes in a buffer object, and if it would cater my needs.
Anyway, here is the final question : Is it possible to create one texture from 4 separate component (buffers) ? Or more precisely : How to draw 4 combined buffers, efficiently , in a context of video sequences?
Thanks in advance,