Make a button on the demoapp to save the video and snap an image at regular intervals

[KalpitBakal]

Hello!

I have been using the Python demoapp to conduct my experiments where I save the video (in a folder) while triggering a pressure pump on the side. I have made a separate 'button' for that. Now I want to make another button which saves the video to a folder and saves the image at regular intervals (I know I need to use QTimer for this) as .tiff format in the same folder. All of this needs to be done while the live video is still playing.

Can you help me a bit with that? I have not quite understood how to save an image from the live video.

[TIS-Tim]

The python demoapp already shows how a video file is created.

Three simple steps:

• Call begin_file to start a new video file:
  

  ic4-examples/python/qt6/demoapp/mainwindow.py

  Line 378 in 704b6d2

  self.video_writer.begin_file(full_path, self.sink.output_image_type, fps)

• Call add_frame repeatedly for each frame you want to add to the video file:
  

  ic4-examples/python/qt6/demoapp/mainwindow.py

  Line 71 in 704b6d2

  self.video_writer.add_frame(buf)

• Call finish_file to finalize the video file:
  

  ic4-examples/python/qt6/demoapp/mainwindow.py

  Line 388 in 704b6d2

  self.video_writer.finish_file()

The python demoapp already shows how to record a video file while live video is playing, so I do not quite understand your question.

[KalpitBakal]

I want to snap and save a .tiff image as well at regular intervals...

[TIS-Tim]

The frames_queued function of the Listener class in the demoapp is executed once for every frame.

Call save_as_tiff on the buffers you want to save.

[KalpitBakal]

` def settime_stress_strain(self,t_step:int,total_step:int,t_pause:int,p_init:int,p_final:int):
self.t_step = t_step
self.total_step = total_step
self.t_pause = t_pause
self.p_init = p_init
self.p_final = p_final

def stressstraintest(self,image_buffer: ic4.ImageBuffer):
        if self.capture_to_video:
            self.stopCapturevideo()
            return
        
        filters = [
            "MP4 Video Files (*.mp4)"
        ]
        
        dialog = QFileDialog(self, "Stress Strain Test")
        dialog.setNameFilters(filters)
        dialog.setFileMode(QFileDialog.FileMode.AnyFile)
        dialog.setAcceptMode(QFileDialog.AcceptMode.AcceptSave)
        dialog.setDirectory(self.save_videos_directory)

        if dialog.exec():
            full_path = dialog.selectedFiles()[0]
            self.save_videos_directory = QFileInfo(full_path).absolutePath()

            fps = float(25)
            try:
                fps = self.device_property_map.get_value_float(ic4.PropId.ACQUISITION_FRAME_RATE)
            except:
                pass
            try:
                fgt_init()
                self.video_writer.begin_file(full_path, self.sink.output_image_type, fps)
                self.p_step = (self.p_final - self.p_init)/self.total_step
                for i in range(self.total_step):
                    self.stop_recording_timer = QTimer(self)
                    self.stop_recording_timer.setTimerType(Qt.PreciseTimer)
                    self.stop_recording_timer.setSingleShot(True)
                    self.image_time = self.t_step
                    self.filename = f"image_{i}.tiff"
                    self.new_full_path = QDir(self.save_videos_directory).filePath(self.filename)
                    self.stop_recording_timer.timeout.connect(lambda buf=image_buffer: buf.save_as_tiff(self.new_full_path))
                    self.stop_recording_timer.start(self.image_time)

                    self.pause_timer = QTimer(self)
                    self.pause_timer.setTimerType(Qt.PreciseTimer)
                    self.pause_timer.setSingleShot(True)
                    self.pause_time = self.t_pause
                    self.pnext = self.p_init + i*self.p_step
                    self.pause_timer.timeout.connect(fgt_set_pressure(0, self.p_next))
                    self.pause_timer.start(self.pause_time)
            

                


            except ic4.IC4Exception as e:
                QMessageBox.critical(self, "", f"{e}", QMessageBox.StandardButton.Ok)

            self.capture_to_video = True
            
        self.updateControls()`

In this everything else works fine, but the image does not get saved. self.stop_recording_timer.timeout.connect(lambda buf=image_buffer: buf.save_as_tiff(self.new_full_path)).

[TIS-Tim]

Well... does the lambda get executed?

And where does image_buffer come from? The program looks a little weird, are you trying to save the same buffer multiple times?

[KalpitBakal]

I have added these functions in the class of Create UI of the mainwindow.py program. I am trying to save the image at regular intervals from the live stream. So my idea was after I press the button Stress Strain test, the stressstraintest function should be executed. However the image does not get saved.

Please let me know if you need more information.

[TIS-Tim]

If you want to save one or multiple images, you have to modify the frames_queued function:

ic4-examples/python/qt6/demoapp/mainwindow.py

Lines 54 to 73 in 704b6d2

	def frames_queued(listener, sink: ic4.QueueSink):
	buf = sink.pop_output_buffer()
	# Connect the buffer's chunk data to the device's property map
	# This allows for properties backed by chunk data to be updated
	self.device_property_map.connect_chunkdata(buf)
	with self.shoot_photo_mutex:
	if self.shoot_photo:
	self.shoot_photo = False
	# Send an event to the main thread with a reference to
	# the main thread of our GUI.
	QApplication.postEvent(self, GotPhotoEvent(buf))
	if self.capture_to_video and not self.video_capture_pause:
	try:
	self.video_writer.add_frame(buf)
	except ic4.IC4Exception as ex:
	pass

That function already has functionality to save images using the video writer when video recording is active.

All you need to do is add some flag to your program (e.g. re-purpose the shoot_photo variable) indicating that the image(s) need to be saved to a tiff file, and act accordingly. It is really that simple.

[KalpitBakal]

Alright. With this I can shoot photo when the shoot photo button is pressed on the GUI right? How can I repurpose it to click an image every 60 seconds, save it and do this for 10 images for example.

Should I put the QTimer in the frames_queued function

[TIS-Tim]

For example:

• Start QTimer when button is pressed
• On QTimer timeout, set shoot_photo flag
• In frames_queued, if shoot_photo is set, call save_as_tiff