protocol/videoprotocol: add screenshot function

Extend the protocol with the screenshot function.

Signed-off-by: Rouven Czerwinski <[email protected]>

Author: Emantor

labgrid/driver/usbvideodriver.py

@@ -182,7 +182,7 @@ def screenshot(self, filename, caps_hint=None, controls=None):
 
         tx_cmd = self.video.command_prefix + ["gst-launch-1.0", "-q"]
         tx_cmd += pipeline.split()
-        rx_cmd = ["gst-launch-1.0", "fdsrc", " num-buffers=75", "!", "jpegdec", "!", "jpegenc", "!", "filesink", f"location={filepath.absolute()}"]
+        rx_cmd = ["gst-launch-1.0", "fdsrc", "num-buffers=75", "!", "decodebin", "!", "jpegenc", "!", "filesink", f"location={filepath.absolute()}"]
 
         tx = subprocess.Popen(
             tx_cmd,

labgrid/protocol/videoprotocol.py

@@ -9,3 +9,7 @@ def get_qualities(self):
     @abc.abstractmethod
     def stream(self, quality_hint=None):
         raise NotImplementedError
+
+    @abc.abstractmethod
+    def screenshot(self, filename):
+        raise NotImplementedError