driver: usbvideodriver: add support for overlaying FPS

CHANGES.rst

@@ -11,6 +11,10 @@ New Features in 25.1
 
 - Guermok HDMI to USB 3.0 capture dongle supported
 
+- The `USBVideoDriver`'s ``stream`` method can now be called with ``fps=True``
+  to embed an overlay with FPS statistics into the video stream.
+  This is exposed in ``labgrid-client video`` via the new ``--fps`` option.
+
 Breaking changes in 25.1
 ~~~~~~~~~~~~~~~~~~~~~~~~
 - The deprecated pytest plugin option ``--env-config`` has been removed. Use

contrib/completion/labgrid-client.bash

@@ -661,7 +661,7 @@ _labgrid_client_video()
 
     case "$cur" in
     -*)
-        COMPREPLY=( $(compgen -W "--quality --controls --name $_labgrid_shared_options" -- "$cur") )
+        COMPREPLY=( $(compgen -W "--quality --controls --fps --name $_labgrid_shared_options" -- "$cur") )
         ;;
     esac
 }

labgrid/driver/usbvideodriver.py

@@ -139,13 +139,15 @@ def get_pipeline(self, path, caps, controls=None):
         return pipeline
 
     @Driver.check_active
-    def stream(self, caps_hint=None, controls=None):
+    def stream(self, caps_hint=None, controls=None, fps=False):
         caps = self.select_caps(caps_hint)
         pipeline = self.get_pipeline(self.video.path, caps, controls)
 
         tx_cmd = self.video.command_prefix + ["gst-launch-1.0", "-q"]
         tx_cmd += pipeline.split()
         rx_cmd = ["gst-launch-1.0", "playbin3", "buffer-duration=0", "uri=fd://0"]
+        if fps:
+            rx_cmd += ["video-sink=fpsdisplaysink"]
 
         tx = subprocess.Popen(
             tx_cmd,

labgrid/remote/client.py

@@ -1313,6 +1313,7 @@ def telnet(self):
     def video(self):
         place = self.get_acquired_place()
         quality = self.args.quality
+        fps = self.args.fps
         controls = self.args.controls
         target = self._get_target(place)
         name = self.args.name
@@ -1342,7 +1343,7 @@ def video(self):
                 mark = "*" if default == name else " "
                 print(f"{mark} {name:<10s} {caps:s}")
         else:
-            res = drv.stream(quality, controls=controls)
+            res = drv.stream(quality, controls=controls, fps=fps)
             if res:
                 exc = InteractiveCommandError("gst-launch-1.0 error")
                 exc.exitcode = res
@@ -1972,6 +1973,7 @@ def main():
 
     subparser = subparsers.add_parser("video", help="start a video stream")
     subparser.add_argument("-q", "--quality", type=str, help="select a video quality (use 'list' to show options)")
+    subparser.add_argument("-f", "--fps", action="store_true", help="Overlay FPS statistics")
     subparser.add_argument(
         "-c", "--controls", type=str, help="configure v4l controls (such as 'focus_auto=0,focus_absolute=40')"
     )