Handle ExposureTimeMode and AnalogueGainMode controls transparently

libcamera now has ExposureTimeMode and AnalogueGainMode mode controls,
which must be set to "manual" before you can set fixed exposure or
gain values. Likewise, the modes must be "cleared" to return to auto
mode (setting zero no longer does anything).

We're going to handle all this transparently for users, because in all
practical cases it adds nothing useful and would be an unwelcome API
change.

Signed-off-by: David Plowman <david.plowman@raspberrypi.com>

Author: davidplowman

picamera2/request.py

@@ -7,6 +7,7 @@
 from pathlib import Path
 from typing import TYPE_CHECKING, Any, Dict, Optional, Union
 
+import libcamera
 import numpy as np
 import piexif
 import simplejpeg
@@ -115,7 +116,25 @@ def release(self) -> None:
                     self.request.reuse()
                     controls = self.picam2.controls.get_libcamera_controls()
                     for id, value in controls.items():
+
+                        # libcamera now has "ExposureTimeMode" and "AnalogueGainMode" which must be set to
+                        # manual for the fixed exposure time or gain to have any effect, and cleared to return
+                        # to "auto " mode. We're going to hide that by supplying them automatically as needed.
+                        if id == libcamera.controls.ExposureTime:
+                            if value:
+                                self.request.set_control(libcamera.controls.ExposureTimeMode, 1)  # manual
+                            else:
+                                self.request.set_control(libcamera.controls.ExposureTimeMode, 0)  # auto
+                                continue  # no need to set the zero value!
+                        elif id == libcamera.controls.AnalogueGain:
+                            if value:
+                                self.request.set_control(libcamera.controls.AnalogueGainMode, 1)  # manual
+                            else:
+                                self.request.set_control(libcamera.controls.AnalogueGainMode, 0)  # auto
+                                continue  # no need to set the zero value!
+
                         self.request.set_control(id, value)
+
                     self.picam2.controls = Controls(self.picam2)
                     self.picam2.camera.queue_request(self.request)
                 [sync.__exit__() for sync in self.syncs]

tests/aegc.py

@@ -0,0 +1,39 @@
+#!/usr/bin/python3
+
+import time
+
+from picamera2 import Picamera2
+
+
+def test_control_fixed(control, value):
+    picam2.set_controls({control: value})
+    time.sleep(1.0)
+    check = picam2.capture_metadata()[control]
+    if abs(check - value) > value * 0.05:
+        print(f"ERROR: requested {control} of {value} but got {check}")
+    else:
+        print(f"Requested {control} of {value}, got {check}")
+
+
+def test_control_auto(control):
+    current = picam2.capture_metadata()[control]
+    picam2.set_controls({control: 0})
+    time.sleep(1.0)
+    for _ in range(5):
+        check = picam2.capture_metadata()[control]
+        if abs(check - current) > current * 0.05:
+            print(f"Control {control} changed from {current} to {check}")
+            return
+    print(f"ERROR: {control} has not returned to auto - still {check}")
+
+
+picam2 = Picamera2()
+picam2.start()
+
+test_control_fixed("ExposureTime", 5000)
+test_control_fixed("ExposureTime", 10000)
+test_control_auto("ExposureTime")
+
+test_control_fixed("AnalogueGain", 1.5)
+test_control_fixed("AnalogueGain", 3.0)
+test_control_auto("AnalogueGain")

tests/test_list.txt

@@ -51,6 +51,7 @@ examples/tuning_file.py
 examples/video_with_config.py
 examples/window_offset.py
 examples/zoom.py
+tests/aegc.py
 tests/alignment.py
 tests/app_dual.py
 tests/app_full_test.py