use python-ffmpeg (run external ffmpeg) to generate video thumb as it also auto-rotates

pa_job_manager.py

@@ -45,6 +45,7 @@ import face_recognition
 import re
 import sys
 import json
+import ffmpeg
 
 
 # global debug setting
@@ -1694,41 +1695,27 @@ def GenImageThumbnail(job, file):
 # GenVideoThumbnail(): log and then generate the thumb for a video (this grabs the width/height of a frame from the video, 
 # and then reads the first few frames until the mean() fo the frame indicates its not just black frame, then make the thumbnail
 ####################################################################################################################################
-def GenVideoThumbnail(job, file):
-    ProcessFileForJob( job, "Generate Thumbnail from Video file: {}".format( file ), file )
+def GenVideoThumbnail( job, fname):
+    ProcessFileForJob( job, f"Generate Thumbnail from Video file: {fname}", fname )
+    height = THUMBSIZE
     try:
-        vcap = cv2.VideoCapture(file)
-        res, frame = vcap.read()
-        first_res = res
-        first_frame = frame
-        frame_cnt=0
-        # if the mean pixel value is > 15, we have something worth making a sshot of (no black frame at start being the sshot)
-        # limit it to 1000 frames jic
-        while res and frame.mean() < 15 and frame_cnt < 1000:
-            res, frame = vcap.read()
-            frame_cnt += 1
-        # if we never got a frame that is not dark, then use first frame
-        if not res:
-            res = first_res
-            frame = first_frame
-            
-        w = vcap.get(cv2.CAP_PROP_FRAME_WIDTH)
-        h = vcap.get(cv2.CAP_PROP_FRAME_HEIGHT)
-        if w > h:
-            factor = w / THUMBSIZE
-        else:
-            factor = h / THUMBSIZE
-        new_h = int(h / factor)
-        new_w = int(w / factor)
-        frame = cv2.resize(frame, (new_w, new_h), 0, 0, cv2.INTER_LINEAR)
-        
-        res, thumb_buf = cv2.imencode('.jpeg', frame)
-        bt = thumb_buf.tobytes()
-        thumbnail = base64.b64encode(bt)
-        thumbnail = str(thumbnail)[2:-1]
-    except Exception as e:
-        AddLogForJob( job, f"ERROR: Failed to Generate thumbnail for video file: {file} - error={e}" )
+        probe = ffmpeg.probe(fname)
+        time = float(probe['streams'][0]['duration']) // 2
+        tmp_fname='/tmp/pa_tmp_'+os.path.basename(fname.split('.')[0])+'.jpg'
+        (
+            ffmpeg
+            .input(fname, ss=time)
+            .filter('scale', -1, height)
+            .output(tmp_fname, vframes=1)
+            .overwrite_output()
+            .run(capture_stdout=True, capture_stderr=True)
+        )
+    except ffmpeg.Error as e:
+        AddLogForJob( job, f"ERROR: Failed to Generate thumbnail for video file: {fname} - error={e}" )
         return None
+
+    thumbnail, w, h = GenThumb( tmp_fname, False )
+    os.remove( tmp_fname )
     return thumbnail
 
 ####################################################################################################################################