Multiple Acquisitions¶
This tutorial will provide an example of starting, stopping, and restarting acquisition, or streaming from a video source.
Configure Streaming¶
To start, we'll create a Runtime object and configure the streaming process. To do this, we'll utilize the setup method. More information on that method is detailed in Utilizing the Setup Method.
import acquire
# Initialize a Runtime object
runtime = acquire.Runtime()
# Grab current configuration and
# Choose Video Source and Storage Device
config = acquire.setup(runtime, "simulated: radial sin", "Tiff")
# Specify settings
config.video[0].storage.settings.filename == "out.tif"
config.video[0].camera.settings.shape = (192, 108)
config.video[0].camera.settings.exposure_time_us = 10e4
config.video[0].max_frame_count = 10
# Update the configuration with the chosen parameters
config = runtime.set_configuration(config)
Start, Stop, and Restart Acquisition¶
During Acquisition, the AvailableData object is the streaming interface. Upon shutdown, Runtime deletes all of the objects created during acquisition to free up resources, and you must stop acquisition by calling runtime.stop() to shutdown after the max frames is collected or runtime.abort() to shutdown immediately) between acquisitions. Otherwise, an exception will be raised.
To understand how acquisition works, we'll start, stop, and repeat acquisition and print the DeviceState, which can be Armed, AwaitingConfiguration, Closed, or Running, as well as print the AvailableData object throughout the process.
If acquisition has ended, all of the objects are deleted, including AvailableData objects, so those will be None when not acquiring data. In addition, if enough time hasn't elapsed since acquisition started, AvailableData will also be None. We'll utilize the time python package to introduce time delays to account for these facts.
# package used to introduce time delays
import time
# start acquisition
runtime.start()
print(runtime.get_state())
print(runtime.get_available_data(0))
# wait 0.5 seconds to allow time for data to be acquired
time.sleep(0.5)
print(runtime.get_state())
print(runtime.get_available_data(0))
# stop acquisition
runtime.stop()
print(runtime.get_state())
print(runtime.get_available_data(0))
# start acquisition
runtime.start()
# time delay of 5 sec > 1 sec acquisition time
time.sleep(5)
print(runtime.get_state())
print(runtime.get_available_data(0))
# stop acquisition
runtime.stop()
The output will be:
DeviceState.Running
None
DeviceState.Running
<builtins.AvailableData object at 0x00000218D685E5B0>
DeviceState.Armed
None
DeviceState.Armed
<builtins.AvailableData object at 0x00000218D685E3D0>
Running, there is no data available.
2. The next print happens after waiting 0.5 seconds, so acquisition is still runnning and now there is acquired data available.
3. The subsequent print is following calling runtime.stop() which waits until the specified max number of frames is collected and then terminates acquisition. Thus, the device is no longer running and there is no available data, since all objects were deleted by calling the stop method. The device is in an Armed state ready for the next acquisition.
4. The final print occurs after waiting 5 seconds following the start of acquisition. This waiting period is longer than the 1 second acqusition time (0.1 seconds/frame and 10 frames), so the device is no longer collecting data. However, runtime.stop() hasn't been called, so the AvailableData object has not yet been deleted.