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Video preparation

Video preparation#

In our paper, we find that when compress and downsample the video size will significally increase the processing speed and saving computation resources and time. Here is one example:

ffmpeg -i mouse.avi -vcodec libx264 -vf scale=720x480 mouse.mp4

Video Compression and Rescaling with FFmpeg#

FFmpeg is a potent tool for video processing, offering capabilities for compression and rescaling. This guide presents the process of compressing and rescaling videos using FFmpeg.

Installing FFmpeg#

conda create --name annolid-env
conda activate annolid-env
conda install -c conda-forge ffmpeg

Verify FFmpeg installation#

ffmpeg -version

Compressing a Video#

Reduce file size while maintaining quality

ffmpeg -i input.mp4 -c:v libx264 -crf 18 output.mp4

Reduce file size and quality

ffmpeg -i input.mp4 -c:v libx264 -b:v 500k output.mp4

Rescaling a Video#

Resize to a specific resolution

ffmpeg -i input.mp4 -filter:v scale=w=1280:h=720 output.mp4

Resize to a specific aspect ratio

ffmpeg -i input.mp4 -filter:v scale=w=1280:h=-1 output.mp4

Compress Videos with Annolid GUI#

  1. Click File -> Downsample Videos.

  2. Select the folder containing your original videos.

  3. Select an output folder to save all the compressed videos.

  4. Set the scale factor:

    • For example, selecting 0.5 will reduce the size of the video by half.

  5. Check the Rescale Video checkbox.

  6. Click the Run Scaling button.

This will compress and downsample all the files in the selected folder.

Additional Tips#

Utilize the -preset option to adjust encoding speed (e.g., -preset fast for faster encoding) Specify the audio codec with -c:a (e.g., -c:a aac for AAC audio) Set the audio bitrate using -b:a (e.g., -b:a 128k for 128 kbps audio)

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