Re: [Flightgear-devel] Saving Videos

[James T. <zak...@ma...>]

On 29 May 2014, at 23:30, Saikrishna Arcot <sai...@gm...> wrote:

> If I recall correctly, jpegfactory is no longer used on Flightgear, and therefore the command-line option no-longer exists.
> 

The cmake switch is gone, because we now use OSG to write screenshots - so the feature is always available.

The command line switch is is 'jpg-httpd’ - and should be the same as it always was (it can actually write PNGs or any other format supported by your OSG now, for video you might conceivably want some less compressed format). This functionality is available in 3.0 releases.

Note the /way/ we acquire frame grabs changed completely, to interact much better with OSG - we no long render the scene again, instead we simply read the framebuffer back after OSG says rendering is complete. You can adjust the maximum frame capture rate, so it should be possible to achieve 25fps output or more this way. I think the default is capped to 5 or 10Hz however.


== setup code in fg_io.cxx ==

  if ( protocol == "jpg-httpd" ) {
            // determine port
            int port = simgear::strutils::to_int(tokens[1]);
            int frameHz = 8; // maximum frame rate
            string type = "jpeg";
            
            if (tokens.size() > 2) {
                frameHz = simgear::strutils::to_int(tokens[2]);
            }
            
            if (tokens.size() > 3) {
                type = tokens[3];
            }
                
      
=========

So for example passing :

  —jpg-http=8080,25,png

Will get you 25fps png available on port 8080 - *assuming* youe machine can keep up!

Torsten’s new HTTPD code is getting related functionality - hopefully using the same backend code to interact with the renderer. I don’t know the status of that but obviously it only applies to nightly builds or code compiled yourself.

Kind regards,
James