Feature request: MJPEG support for video output from V4L

[deliciouslytyped]

X11VNC supports outputting video from V4L devices as the VNC video stream, but the set of supported encodings is limited.
What would it take and how could it be implemented to support MJPEG?

I may attempt this myself. It's been a few months but I did look at the code a bit, however it wasn't completely clear to me with the amount of time I invested.

xref rvaiya/keyd#838 (comment)

[deliciouslytyped]

@bk138 I'm trying to have another go at this.

As the ex-maintainer, do you have any idea how x11vnc is set up to work at a high level? It doesn't seem like the cleanest code ever.

I'd like to patch in sending already compressed JPEG (MJPEG) frames, from a v4l2 device. LibVNC/libvncserver#235 seems to provide some basis for this in libvncserver, but at this point I don't really understand how x11vnc works.

It seems like x11vnc gets frames from various kinds of file descriptors providing images, copies the images to a frame buffer, and does various operations on that.

Then some how libvnc gets involved for the RFB protocol stuff.

From an initial exploration, it looks like x11vnc implements the libvncserver "event loop" by manually calling event processing with rfbPE(...)?

I'm not sure what the best way to try implementing this would be, given that I imagine in need to bypass the standard framebuffer processing. (I don't want to decompress the jpeg frames, so its just whole-screen images.)

Thanks.

[deliciouslytyped]

I also see instances of rfbRunEventLoop so now all bets are off 🤷

[deliciouslytyped]

Well, I figured out how some of the stuff works, but overall x11vnc seems too spaghetti for me to try actually implementing this without further work. I'm switching to trying to write my own thing with libVNCserver based on the information in:

• Is it possible to use jpeg data in frame buffer, instead of rgb data(from jpeg)? libvncserver#232
• Tight: export SendCompressedData and SendTightHeader functions libvncserver#235

[deliciouslytyped]

I was able to get the basic idea working, though I didn't implement it with x11vnc.

It's very similar and closely based off the LibVNCServer code from the openbmc ikvm server linked here LibVNC/libvncserver#235 (comment) ;

[Neustradamus]

To follow this interesting request.