A way to save 360° panorama video What is the best way to save video from faces of a cube? The render can produce 6 squares (90°x90°) of 1024x1024 resolution. Faces oriented along axies and only position is changed continuously. I want to save them into the video stream and then play back them into 360° panorama viewver by means of projection on the cube or using cubemap (OpenGL ES).

What is the best codec suitable and what is the best way to save video for above purposes? Is it better to use six separate synchronized video streams or, instead, to enclose all six faces into the one?

If cube is unfolded into six square bitmaps and composed into a 3x2 (or 2x3) rectangle, then it is possible to get artifacts on glued inner edges and on the outer edge of the resulting rectangle. I sure it may depend on codec used to compress/decompress resulting video.

In case of 6 separate video streams it is possible to render only 5 of 6 (or 3 of 6 in case of only pitch and yaw (but not roll) rotations are possible) faces of cube, i.e. only visible ones. But on the other hand it may be waste of resources to support six separate streams due to necessity of attendant metainformation handling.

What are expected performance issues inherent to different approaches?

The relevant platform is average home desktop PC.
I would be tempted to use a solution which involves decoding a single rectangular video stream so you don't need any special video decoder. As you have said there will be performance penalties for decoding multiple seperate streams. 

Something like octohedran cube maps might be a good offline way to convert 6 video streams into a single video stream while minimizing distortion. A relatively cheap pixel shader can be used to project the 'cube' map back to camera space.

Further reading here > http://www.vis.uni-stuttgart.de/~engelhts/paper/vmvOctaMaps.pdf