Compress MP4 Video Files With FFMPEG

Need to reduce the file size of MP4 video files? A few simple FFMPEG commands make it easy.

Quick and straightforward video compression is advantageous as part of an ETL pipeline for preprocessing AI/ML data or reducing video file sizes for a website.

Compression Commands

# libx265 can offer around 25–50% savings compared to H.264 video encoded with libx264
ffmpeg -i input.mp4 -vcodec libx265 output.mp4

# libx264 offers more compatibility, e.g., static site generators
ffmpeg -i input.mp4 -vcodec libx264 output.mp4

You can also add a Constant Rate Factor (CRF) flag (-crf) to more finely control the quality vs. size of the output. The range of the CRF scale is exponential and accepts values between 0–51:

• 0 is lossless
• 23 is the default
• 51 is the worst quality possible

Looping Over a Directory

Have a bunch of files that need to be compressed all at once? Loop over a directory with the following:

for F in *.mp4; \
  do ffmpeg -i $F -vcodec libx264 temp.mp4 \
    && mv -f temp.mp4 $F; \
  done