strix

commit f4a1ff98b5c80eb64cda18c8253b45fc3d9e87a2
parent 543296438edf098cf0d1923278c7c29f124b3de8
Author: Brian C. Lane <bcl@brianlane.com>
Date:   Mon, 30 May 2022 21:01:18 -0700

thumbnails: Switch to better thumbnail selection

Previously it was picking the image that was 25% from the start of the
event. This worked, mostly, but I have been tagging all the images with
data about them from motion. They contain the changed pixel count,
coordinates of the box for movement, and the noise level.

The box isn't a great way to tell if it has the 'best' picture because
it can cover a larger area than the actual changes (eg. two separate
active areas are included in the box).

So I now sort based on the changed pixel count and pick the largest one.
So far this seems to work better than the 25% method.

Diffstat:
M
src/strix/queue.py
 | 
71
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-----

1 file changed, 66 insertions(+), 5 deletions(-)
diff --git a/src/strix/queue.py b/src/strix/queue.py
@@ -15,6 +15,7 @@
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 from glob import glob
+import json
 import multiprocessing as mp
 import os
 import shutil
@@ -31,6 +32,67 @@ THUMBNAIL_SIZE = (640, 480)
 def max_cores() -> int:
     return max(1, mp.cpu_count() // 2)
 
+
+def GetImageDescriptions(path):
+    """
+    Extract EXIF ImageDescription for all the images in the directory
+    """
+    ## Run exiftool on the files
+    cmd = ["exiftool", "-json", "-q", "-ImageDescription", path]
+    try:
+        out = subprocess.check_output(cmd)
+        j = json.loads(out)
+        return [d for d in j if "ImageDescription" in d]
+    except subprocess.CalledProcessError:
+        pass
+
+    return []
+
+
+def DescriptionDict(desc):
+    """
+    Split the motion info into dict entries
+
+    <changed>-<noise>-<width>-<height>-<X>-<Y>
+    """
+    try:
+        changed, noise, width, height, x, y = desc.split("-")
+        return {
+            "changed": int(changed),
+            "noise": int(noise),
+            "width": int(width),
+            "height": int(height),
+            "x": int(x),
+            "y": int(y),
+            "area": int(width) * int(height)
+        }
+    except ValueError:
+        return {
+            "changed": 0,
+            "noise": 0,
+            "width": 0,
+            "height": 0,
+            "x": 0,
+            "y": 0,
+            "area": 0
+        }
+
+
+def BestThumbnail(path):
+    """
+    Make a best guess at the image to use for a thumbnail
+
+    Use the one with the most changes.
+    """
+    data = GetImageDescriptions(path)
+
+    images = []
+    for i in data:
+        images.append({"name": i["SourceFile"], "description": DescriptionDict(i["ImageDescription"])})
+    sorted_images = sorted(images, key=lambda i: i["description"]["changed"], reverse=True)
+    return sorted_images[0]["name"]
+
+
 ## Handle watching the queue and dispatching movie creation and directory moving
 
 def process_event(log: structlog.BoundLogger, base_dir: str, event: str) -> None:
@@ -71,12 +133,10 @@ def process_event(log: structlog.BoundLogger, base_dir: str, event: str) -> None
     except Exception as e:
         log.error("Failed to create debug video", exception=str(e))
 
-    # Create a thumbnail of the 25% image of the capture, on the theory that it
-    # has the best chance of being 'interesting' since it is near the trigger point
     try:
-        images = sorted(list(glob(os.path.join(event_path, "*.jpg"))))
-        idx = images[int(len(images)//4)]
-        im = Image.open(idx)
+        # Get the image with the highest change value
+        thumbnail = BestThumbnail(event_path)
+        im = Image.open(thumbnail)
         # im.size will get the actual size of the image
         im.thumbnail(THUMBNAIL_SIZE)
         im.save(os.path.join(event_path, "thumbnail.jpg"), "JPEG")
@@ -86,6 +146,7 @@ def process_event(log: structlog.BoundLogger, base_dir: str, event: str) -> None
     # Move the directory to its final location
     try:
         # Use the time of the first image
+        images = sorted(list(glob(os.path.join(event_path, "*-*-*-*.jpg"))))
         first_jpg = os.path.split(images[0])[1]
         first_time = first_jpg.rsplit("-", 1)[0]
         event_path_base = os.path.split(event_path)[0]