add extracting frames from video tutorial

Author: x4nth055

Diff for: README.md

@@ -170,6 +170,7 @@ This is a repository of all the tutorials of [The Python Code](https://www.thepy
     - [How to Combine a Static Image with Audio in Python](https://www.thepythoncode.com/article/add-static-image-to-audio-in-python). ([code](python-for-multimedia/add-photo-to-audio))
     - [How to Concatenate Video Files in Python](https://www.thepythoncode.com/article/concatenate-video-files-in-python). ([code](python-for-multimedia/combine-video))
     - [How to Concatenate Audio Files in Python](https://www.thepythoncode.com/article/concatenate-audio-files-in-python). ([code](python-for-multimedia/combine-audio))
+    - [How to Extract Frames from Video in Python](https://www.thepythoncode.com/article/extract-frames-from-videos-in-python). ([code](python-for-multimedia/extract-frames-from-video))
 
 
 For any feedback, please consider pulling requests.

Diff for: python-for-multimedia/extract-frames-from-video/README.md

@@ -0,0 +1,4 @@
+# [How to Extract Frames from Video in Python](https://www.thepythoncode.com/article/extract-frames-from-videos-in-python)
+To run this:
+- `pip3 install -r requirements.txt`
+- Use `extract_frames_opencv.py` for using OpenCV to extract frames, or use `extract_frames_moviepy.py` for using MoviePy library.

Diff for: python-for-multimedia/extract-frames-from-video/extract_frames_moviepy.py

@@ -0,0 +1,47 @@
+from moviepy.editor import VideoFileClip
+import numpy as np
+import os
+from datetime import timedelta
+
+# i.e if video of duration 30 seconds, saves 10 frame per second = 300 frames saved in total
+SAVING_FRAMES_PER_SECOND = 10
+
+def format_timedelta(td):
+    """Utility function to format timedelta objects in a cool way (e.g 00:00:20.05) 
+    omitting microseconds and retaining milliseconds"""
+    result = str(td)
+    try:
+        result, ms = result.split(".")
+    except ValueError:
+        return result + ".00".replace(":", "-")
+    ms = int(ms)
+    ms = round(ms / 1e4)
+    return f"{result}.{ms:02}".replace(":", "-")
+
+
+def main(video_file):
+    # load the video clip
+    video_clip = VideoFileClip(video_file)
+    # make a folder by the name of the video file
+    filename, _ = os.path.splitext(video_file)
+    filename += "-moviepy"
+    if not os.path.isdir(filename):
+        os.mkdir(filename)
+
+    # if the SAVING_FRAMES_PER_SECOND is above video FPS, then set it to FPS (as maximum)
+    saving_frames_per_second = min(video_clip.fps, SAVING_FRAMES_PER_SECOND)
+    # if SAVING_FRAMES_PER_SECOND is set to 0, step is 1/fps, else 1/SAVING_FRAMES_PER_SECOND
+    step = 1 / video_clip.fps if saving_frames_per_second == 0 else 1 / saving_frames_per_second
+    # iterate over each possible frame
+    for current_duration in np.arange(0, video_clip.duration, step):
+        # format the file name and save it
+        frame_duration_formatted = format_timedelta(timedelta(seconds=current_duration)).replace(":", "-")
+        frame_filename = os.path.join(filename, f"frame{frame_duration_formatted}.jpg")
+        # save the frame with the current duration
+        video_clip.save_frame(frame_filename, current_duration)
+
+
+if __name__ == "__main__":
+    import sys
+    video_file = sys.argv[1]
+    main(video_file)

Diff for: python-for-multimedia/extract-frames-from-video/extract_frames_opencv.py

@@ -0,0 +1,80 @@
+from datetime import timedelta
+import cv2
+import numpy as np
+import os
+
+# i.e if video of duration 30 seconds, saves 10 frame per second = 300 frames saved in total
+SAVING_FRAMES_PER_SECOND = 10
+
+def format_timedelta(td):
+    """Utility function to format timedelta objects in a cool way (e.g 00:00:20.05) 
+    omitting microseconds and retaining milliseconds"""
+    result = str(td)
+    try:
+        result, ms = result.split(".")
+    except ValueError:
+        return result + ".00".replace(":", "-")
+    ms = int(ms)
+    ms = round(ms / 1e4)
+    return f"{result}.{ms:02}".replace(":", "-")
+
+
+def get_saving_frames_durations(cap, saving_fps):
+    """A function that returns the list of durations where to save the frames"""
+    s = []
+    # get the clip duration by dividing number of frames by the number of frames per second
+    clip_duration = cap.get(cv2.CAP_PROP_FRAME_COUNT) / cap.get(cv2.CAP_PROP_FPS)
+    # use np.arange() to make floating-point steps
+    for i in np.arange(0, clip_duration, 1 / saving_fps):
+        s.append(i)
+    return s
+
+
+def main(video_file):
+    filename, _ = os.path.splitext(video_file)
+    filename += "-opencv"
+    # make a folder by the name of the video file
+    if not os.path.isdir(filename):
+        os.mkdir(filename)
+    # read the video file    
+    cap = cv2.VideoCapture(video_file)
+    # get the FPS of the video
+    fps = cap.get(cv2.CAP_PROP_FPS)
+    # if the SAVING_FRAMES_PER_SECOND is above video FPS, then set it to FPS (as maximum)
+    saving_frames_per_second = min(fps, SAVING_FRAMES_PER_SECOND)
+    # get the list of duration spots to save
+    saving_frames_durations = get_saving_frames_durations(cap, saving_frames_per_second)
+    # start the loop
+    count = 0
+    while True:
+        is_read, frame = cap.read()
+        if not is_read:
+            # break out of the loop if there are no frames to read
+            break
+        # get the duration by dividing the frame count by the FPS
+        frame_duration = count / fps
+        try:
+            # get the earliest duration to save
+            closest_duration = saving_frames_durations[0]
+        except IndexError:
+            # the list is empty, all duration frames were saved
+            break
+        if frame_duration >= closest_duration:
+            # if closest duration is less than or equals the frame duration, 
+            # then save the frame
+            frame_duration_formatted = format_timedelta(timedelta(seconds=frame_duration))
+            cv2.imwrite(os.path.join(filename, f"frame{frame_duration_formatted}.jpg"), frame) 
+            # drop the duration spot from the list, since this duration spot is already saved
+            try:
+                saving_frames_durations.pop(0)
+            except IndexError:
+                pass
+        # increment the frame count
+        count += 1
+
+
+
+if __name__ == "__main__":
+    import sys
+    video_file = sys.argv[1]
+    main(video_file)

Diff for: python-for-multimedia/extract-frames-from-video/requirements.txt

@@ -0,0 +1,2 @@
+python-opencv
+moviepy