[FFmpeg-user] Streaming Formats, video overlays, other options?

[William C Bonner]

I've got a question about streaming formats, video overlays, and what I
might search about for learning the possibilities. I perhaps know too much
and have become lost in the possibilities.

First, what I'd like to do: Use a low powered computer along with a camera
that produces H264 to generate video streams that can be optionally
overlayed at a receiving computer that has significantly more processing
power. I'd like the sender to send a video stream of the camera output, and
a second video stream of simple data related to the time / location /
direction / orientation of the camera. It's essentially a heads up display
overlay.

I know that DVDs produce their subtitles as a video overlay track, that can
be optionally enabled at the player and it seems to me that my data would
be a very simple video overlay compared to the underlying video stream. I
could easily produce the frames in the sender 30 times a second and believe
that they would compress much more efficiently than the camera video
stream, since most of my stream would simply be marked as transparent. I'm
hoping to not be required to transcode the camera video stream from h264
back to h264 with the overlay because so far my experience has been that my
sender cannot manage to keep up with the transcoding while it only loads
the CPU about 3% to simply do the demux/mux process.

Any pointers would be helpful. Doing this on linux, I was thinking to do
this using an FFMPEG command that got it's primary video stream from
/dev/video0 and got it's secondary input from a pipe where my program
output individual images in either GIF or PNG format, or whatever image
format might support transparent pixels.

Thanks. Wim.