Added option to duplicate frames instead of inserting black ones.

Author: fnunnari

PythonTools/video.py

@@ -135,7 +135,21 @@ def extract_frames_ffmpeg(video_file: str, timestamps_df: pd.DataFrame, output_d
         ffmpeg_read_process = None
 
 
-def rebuild_video(dir: Path, frames: pd.DataFrame, video_info: VideoInfo, outfile: Path) -> None:
+def rebuild_video(dir: Path, frames: pd.DataFrame, video_info: VideoInfo, outfile: Path, duplicate_last: bool = False)\
+        -> None:
+
+    """
+    Given the directory containing unpacked frames and the dataframe, rebuilds a new video at teh given path.
+    :param dir: The directory containing the single frames. Each frame with name specified in the frames dadaframe
+    :param frames: A dataframe with two columns: `timestamp` is the name of the frame to append to the video,
+     and `generated` can be either `Original` (file should be loaded) or `Generated` (insert a black frame or duplicate last).
+    :param video_info: Anticipated info regarding the resolution of the output video.
+     Resolution must match the resolution of input frame images.
+    :param outfile: Path to the video output file.
+    :param duplicate_last: If False (default) a black frame is inserted whenever a `Generated` frame is found.
+     When True, the last valid frame is duplicated.
+    :return: Nothing
+    """
 
     # Extract the vido information.
     frame_width = video_info.width
@@ -164,6 +178,10 @@ def rebuild_video(dir: Path, frames: pd.DataFrame, video_info: VideoInfo, outfil
 
     assert frame_width is not None and frame_height is not None and ffmpeg_video_out_process is not None
 
+    # Initialize data for "Generated" frames
+    black_frame = np.zeros((frame_height, frame_width, 3), dtype=np.uint8)
+    last_frame = black_frame
+
     #
     # Cycle through all the frames.
     for idx, row in frames.iterrows():
@@ -190,12 +208,18 @@ def rebuild_video(dir: Path, frames: pd.DataFrame, video_info: VideoInfo, outfil
             # Send the frame to the ffmpeg process
             ffmpeg_video_out_process.stdin.write(img.tobytes())
 
+            last_frame = img
+
         elif gen == "Generated":
 
-            # Create an artificial black frame
-            print(f"Injecting Black frame at idx {idx}")
-            black_frame = np.zeros((frame_height, frame_width, 3), dtype=np.uint8)
-            ffmpeg_video_out_process.stdin.write(black_frame.tobytes())
+            if duplicate_last:
+                pass
+                print("Duplicating last valid frame")
+                ffmpeg_video_out_process.stdin.write(last_frame.tobytes())
+            else:
+                # Create an artificial black frame
+                print(f"Injecting Black frame at idx {idx}")
+                ffmpeg_video_out_process.stdin.write(black_frame.tobytes())
 
         else:
             raise Exception(f"Unexpected value '{gen}' in column 'generated' at index {idx}")