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Looping a Video

Create a looped version of a video file using FFmpeg, repeating the content for a specified number of times or duration.

VideoAlchemy Compose File

version: 1

generate_path: "./generated"

tasks:
  - name: Looping a Video
    command: ffmpeg
    inputs:
      - id: input_1
        source: 'input.mp4'
    codecs:
      - stream_loop: -1
        codec_name:
          video: copy
          audio: copy
        shortest: true
    outputs:
      - id: output_1
        overwrite: true
        source: 'output.mp4'

Command

ffmpeg -stream_loop -1 -i input.mp4 -c copy -shortest output.mp4

Parameters

  • -stream_loop -1: Loops the input video infinitely. Replace -1 with a specific number (e.g., 5) to loop the video a fixed number of times.
  • -i input.mp4: Specifies the input video file. Replace input.mp4 with the path to your source video file.
  • -c copy: Copies the video and audio streams without re-encoding, preserving the original quality.
  • -shortest: Makes the output file duration equal to the shortest input stream (useful when combining with audio that may not match the exact loop duration).

Possible Errors

  • File not found: Occurs if FFmpeg cannot locate the input file. Ensure the path to the file is correct.
  • Infinite loop: If the -stream_loop option is set to -1 without setting a duration limit or using -shortest, FFmpeg may attempt to create an infinitely long file. Ensure your command includes appropriate limiting parameters.
  • Permission denied: Arises if FFmpeg does not have the necessary permissions to read the input file or write to the output file. Check that the files and directories have the correct permissions.

GPU Acceleration Command

Looping a video involves primarily stream manipulation rather than encoding, so GPU acceleration does not directly apply. However, if you need to re-encode the video for any reason (e.g., changing format or size), you can incorporate GPU acceleration for the encoding process. For Nvidia GPUs:

ffmpeg -stream_loop -1 -i input.mp4 -c:v h264_nvenc -c:a copy -shortest output.mp4

Additional Information

  • Audio Looping: If your video has audio, consider the audio length and how it aligns with the video loop. Misalignment may result in abrupt audio cuts or mismatches between video and audio loops.
  • File Size: Looping a video multiple times will increase the file size proportionally. Consider this when planning storage or streaming bandwidth.
  • Re-encoding vs. Copying: Using -c copy preserves quality but limits format changes. If you need to change the video or audio codec, specify the codec with -c:v for video and -c:a for audio, and be aware this will involve re-encoding.
  • Complex Looping: For more complex looping scenarios, such as looping a segment of a video or integrating loops with non-looped content, you may need to use more advanced FFmpeg features or scripts to create the desired output.