Articles on: The editor

Preparing your video for scrub on scroll


A video used with scrub on scroll must be an MP4 file with H.264 encoding, 60 seconds or less, 50 MB or less, and 1920 × 1080 pixels or less in total (width × height). If your video doesn't meet these requirements, re-encode it with HandBrake using the steps below.


Video requirements


A video works with scrub on scroll only when it meets all of these requirements:


  • Format: MP4 file with H.264 encoding.
  • Length: 60 seconds or less.
  • File size: 50 MB or less.
  • Resolution: 1920 × 1080 pixels or less in total (width × height). A portrait video of 1080 × 1920 also meets this limit.


If a video goes over one of these limits, scrub on scroll is switched off for that video, and the editor preview shows an "Encoding failed" message. The message names only one limit, even when the video goes over more than one, so check the video against all of the limits above before you upload it again.


Use a resolution of 1280 × 720 (or 720 × 1280 for portrait video) where possible. A larger video doesn't look sharper when scrubbed, but it is more likely to go over the 50 MB limit. Visitors also have to wait for the whole video to download before scrubbing starts, so a smaller file means a shorter wait.


Videos recorded on a phone are often encoded in H.265 (HEVC), even when the file is an MP4. Re-encode these videos to H.264 before you upload them, or they won't scrub smoothly.


Re-encoding a video with HandBrake


To re-encode a video so it meets the scrub on scroll requirements (MP4 with H.264 encoding, 60 seconds or less, 50 MB or less, and 1920 × 1080 pixels or less in total), use HandBrake, a free video converter.


  1. Open your video in HandBrake.
  2. Choose a 720p preset as a starting point, for example Fast 720p30.


Handbrake preset as start point


  1. On the Summary tab, tick Web Optimized.


Optimize video for web


  1. On the Video tab, set Video Encoder to H.264 (x264).
  2. On the Video tab, enter keyint=10 in the Additional Options field.


Make sure the video has keyframes


  1. Optional: on the Audio tab, remove the audio track. Scrubbed videos don't play sound, so this makes the file smaller.
  2. Click Start Encode (Start on Mac).
  3. Check that the new file is 60 seconds or less and 50 MB or less, then upload it to Maglr and select it in the Video field of the video element's settings.


The keyint setting controls how often the video contains a keyframe (a complete image). Current versions of Chrome, Edge, Firefox and Safari scrub smoothly without it. Older browsers play the video as a normal video and need frequent keyframes to scrub smoothly. A lower value gives smoother scrubbing in those browsers but a bigger file.


Frequently asked questions


Why does my video show "Encoding failed" in the preview?


The video is longer than 60 seconds, larger than 50 MB, or has more than 1920 × 1080 pixels in total (width × height). Until the video meets all three limits, scrub on scroll is switched off for it. The message names only one limit, even when the video goes over more than one, so check all three. Shorten, compress or resize the video, for example with HandBrake, then upload it to Maglr and select it in the Video field of the video element's settings.


Why doesn't my phone video scrub smoothly?


Phones often record video in H.265 (HEVC), and scrub on scroll needs an MP4 file with H.264 encoding. Re-encode the video to H.264, for example with HandBrake, then upload it to Maglr and select it in the Video field of the video element's settings.


Can I use a YouTube or Vimeo video with scrub on scroll?


No. YouTube and Vimeo videos can't be used with scrub on scroll. Use an MP4 file with H.264 encoding instead.

Updated on: 15/10/2026