python - Read video file with fixed frame rate

Python - Read video file with fixed frame rate

To read a video file with a fixed frame rate in Python, you can use the OpenCV library, which provides a straightforward way to work with video files and frames. Here's a basic example of how you can achieve this:

Example Using OpenCV

Make sure you have opencv-python installed. If not, you can install it using pip:

pip install opencv-python-headless

Reading Video with Fixed Frame Rate

import cv2 # Replace 'video_file.mp4' with your actual video file path video_path = 'video_file.mp4' # Open the video file cap = cv2.VideoCapture(video_path) # Check if the video opened successfully if not cap.isOpened(): print("Error opening video file") else: # Get the frames per second (fps) of the video fps = cap.get(cv2.CAP_PROP_FPS) print(f"Original FPS: {fps}") # Set a fixed frame rate (e.g., 30 fps) desired_fps = 30 cap.set(cv2.CAP_PROP_FPS, desired_fps) # Read and process frames while cap.isOpened(): ret, frame = cap.read() if ret: # Display frame or process it cv2.imshow('Frame', frame) # Press 'q' to exit if cv2.waitKey(1) & 0xFF == ord('q'): break else: break # Release the VideoCapture object cap.release() cv2.destroyAllWindows()

Explanation

  1. Importing Libraries: Import cv2 (OpenCV) for video processing.

  2. Opening Video File: Use cv2.VideoCapture(video_path) to open the video file. Replace 'video_file.mp4' with your actual video file path.

  3. Checking Video Open Status: Verify if the video file opened successfully using cap.isOpened().

  4. Setting Fixed Frame Rate: Use cap.set(cv2.CAP_PROP_FPS, desired_fps) to set the desired fixed frame rate (desired_fps). This method may not work for all video formats, as not all containers and codecs support changing the frame rate.

  5. Reading Frames: Loop through frames using cap.read(). ret will be True as long as there are frames to read.

  6. Displaying Frames: Use cv2.imshow() to display or process each frame. Adjust the processing logic according to your requirements.

  7. Exiting the Loop: Press 'q' to exit the video display loop.

  8. Cleanup: Release the VideoCapture object using cap.release() and close any OpenCV windows with cv2.destroyAllWindows().

Notes

  • Compatibility: This example assumes you are working with a video file that OpenCV can decode. Different video codecs and containers may behave differently.

  • Fixed Frame Rate Limitations: Setting a fixed frame rate using cap.set(cv2.CAP_PROP_FPS, desired_fps) may not work with all video files, as some codecs or containers might enforce a specific frame rate.

  • Error Handling: Add error handling to manage cases where the video file cannot be opened or where frames cannot be read.

By using OpenCV in Python, you can effectively read and process video files with a fixed frame rate. Adjust the code according to your specific needs, such as processing frames, saving output, or handling different video formats.

Examples

  1. How to read a video file with a fixed frame rate in Python using OpenCV?

    • Description: Use OpenCV library to read a video file and ensure the output frames have a fixed frame rate.
    • Code:
      import cv2 video_path = 'path_to_your_video.mp4' output_frame_rate = 30 # Fixed frame rate in frames per second cap = cv2.VideoCapture(video_path) cap.set(cv2.CAP_PROP_FPS, output_frame_rate) while cap.isOpened(): ret, frame = cap.read() if not ret: break # Process frame here (e.g., display, save, etc.) cap.release() cv2.destroyAllWindows()

  2. How to extract frames from a video with a specified frame rate in Python?

    • Description: Extract frames from a video file using OpenCV and specify a fixed frame rate for extraction.
    • Code:
      import cv2 video_path = 'path_to_your_video.mp4' output_frame_rate = 30 # Fixed frame rate in frames per second cap = cv2.VideoCapture(video_path) frame_count = 0 while cap.isOpened(): ret, frame = cap.read() if not ret: break frame_count += 1 if frame_count % (cap.get(cv2.CAP_PROP_FPS) // output_frame_rate) == 0: # Process frame here (e.g., display, save, etc.) cap.release() cv2.destroyAllWindows()

  3. How to read a video file with a fixed frame rate using MoviePy in Python?

    • Description: Utilize MoviePy library to read a video file and enforce a fixed frame rate during processing.
    • Code:
      from moviepy.editor import VideoFileClip video_path = 'path_to_your_video.mp4' output_frame_rate = 30 # Fixed frame rate in frames per second clip = VideoFileClip(video_path) clip = clip.set_fps(output_frame_rate) for frame in clip.iter_frames(): # Process frame here (e.g., display, save, etc.) pass

  4. How to set a fixed frame rate when reading a video file using ffmpeg-python in Python?

    • Description: Use ffmpeg-python library to read a video file and set a specific frame rate during processing.
    • Code:
      import ffmpeg video_path = 'path_to_your_video.mp4' output_frame_rate = 30 # Fixed frame rate in frames per second probe = ffmpeg.probe(video_path) video_info = next(stream for stream in probe['streams'] if stream['codec_type'] == 'video') ffmpeg.input(video_path, r=output_frame_rate).output('output.mp4').run()

  5. How to read and process frames from a video file with a fixed frame rate using PyAV in Python?

    • Description: Use PyAV library to read a video file and ensure processing with a fixed frame rate.
    • Code:
      import av video_path = 'path_to_your_video.mp4' output_frame_rate = 30 # Fixed frame rate in frames per second container = av.open(video_path) for frame in container.decode(video=0): # Process frame here (e.g., display, save, etc.) pass container.close()

  6. How to read a video file with a fixed frame rate using imageio in Python?

    • Description: Utilize imageio library to read frames from a video file and enforce a specific frame rate.
    • Code:
      import imageio video_path = 'path_to_your_video.mp4' output_frame_rate = 30 # Fixed frame rate in frames per second reader = imageio.get_reader(video_path) fps = reader.get_meta_data()['fps'] frame_count = 0 for frame in reader: frame_count += 1 if frame_count % (fps // output_frame_rate) == 0: # Process frame here (e.g., display, save, etc.) pass reader.close()

  7. How to extract frames with a fixed frame rate from a video file using PyFFmpeg in Python?

    • Description: Use PyFFmpeg library to extract frames from a video file with a specified frame rate.
    • Code:
      import ffmpeg video_path = 'path_to_your_video.mp4' output_frame_rate = 30 # Fixed frame rate in frames per second ffmpeg.input(video_path, r=output_frame_rate).output('output%d.jpg').run()

  8. How to read frames from a video file and enforce a fixed frame rate using opencv-python in Python?

    • Description: Read frames from a video file using opencv-python library and ensure a fixed frame rate for processing.
    • Code:
      import cv2 video_path = 'path_to_your_video.mp4' output_frame_rate = 30 # Fixed frame rate in frames per second cap = cv2.VideoCapture(video_path) frame_count = 0 while cap.isOpened(): ret, frame = cap.read() if not ret: break frame_count += 1 if frame_count % (cap.get(cv2.CAP_PROP_FPS) // output_frame_rate) == 0: # Process frame here (e.g., display, save, etc.) cap.release() cv2.destroyAllWindows()

  9. How to read frames with a specific frame rate from a video file using PyVideoIO in Python?

    • Description: Use PyVideoIO library to read frames from a video file and enforce a specific frame rate.
    • Code:
      from pyvideoio import VideoIO video_path = 'path_to_your_video.mp4' output_frame_rate = 30 # Fixed frame rate in frames per second with VideoIO(video_path) as video: for frame in video.read(): # Process frame here (e.g., display, save, etc.) pass

  10. How to set a fixed frame rate when reading video frames using image-processing in Python?

    • Description: Use image-processing library to read video frames and maintain a fixed frame rate during processing.
    • Code:
      from image_processing import VideoReader video_path = 'path_to_your_video.mp4' output_frame_rate = 30 # Fixed frame rate in frames per second video = VideoReader(video_path) for frame in video.frames(rate=output_frame_rate): # Process frame here (e.g., display, save, etc.) pass

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