Recording help

This page is to help authors to record their presentation. Requirements of the said presentation are available in the author instructions.

While we are unable to provide individualized technical support to help you create these videos, we provide on this page several examples on how to record a video of your presentation, and some instructions to convert the recording if needed.

Quick reminder of the requirement:

  • 16/9 aspect ratio
  • Resolution at least 1920x1080p
  • 20 frame per second or more
  • Saved in .mp4 format
  • Audio channel in mono or stereo (no 5.1 or any creative setup)
  • Less than 200MB in total

Recording on MacOS

Quicktime (available on all MacOS installations) allows to easily record and edit your entire screen:

Recording with zoom

One possible approach to record a compatible video from content displayed on your computer screen and voice recorded via the computer microphone, is to record the presentation using Zoom, available to users on most platforms and in most countries:

Converting formats

ffmpeg (available on Linux, OSX and Windows) can be used to easily reencode a recording into .mp4:

ffmpeg -i input.avi output.mp4

Reducing the video size

If you are a bit above the size limit of OpenReview, you can always recompress the recording. For instance:

 ffmpeg -i input.mp4 -vcodec libx265 -crf 28 output.mp4

You can increase the compression level by pushing the -crf value a bit.

Trim bits of the video

You may end-up with some unwanted sequence, when you start and stop the recording process. It is possible to cut those bits quite easily:

ffmpeg -ss [start] -i in.mp4 -t [duration] -c copy out.mp4

Advanced users

Advanced users might want have more control on the recording. While it is more complex, and will certainly require some tuning (with the encoder parameters), this might give them more options to get exatly what they want.

Recording with ffmpeg

Recording a screen is possible with ffmpeg.

For instance on Linux, with a screen of 3840x2160 resolution:

ffmpeg -video_size 3840x2160 -framerate 25 -f x11grab -i :0.0 \
    -f pulse -ac 2 -i default \
    -c:v libx264 -crf 0 -preset veryfast raw_output.mp4

And then downsample it to 1080p:

ffmpeg -i raw_output.mp4 -vf scale=1920:1080 output_1080p.mp4

If you also want to include your webcam on the bottom right corner of the video:

ffmpeg -video_size 1920x1080 -framerate 25 -f x11grab -i :0.0 \
    -f v4l2 -framerate 25 -video_size 640x480 -i /dev/video0 \
    -filter_complex "[0][1]overlay=x=W-w:y=H-h" \
    -f pulse -ac 2 -i default \
    -c:v libx264 -crf 0 -preset veryfast raw_output_webcam.mp4