I'm editing a small animation video (.mp4) of our app with After Effects (cropping composition to region of interest). I then add the composition to Adobe Media Encoder Queue and process it with the preset on my composition being Match source - High bitrate, encoded at H.264 as it's meant to be displayed on the web. Initially the filesize of the file is 8.3mb - after rendering, it's 30mb+ ! Why is this happening (I don't see how the quality can be better than it initially is) and what settings should I be using to export the .MP4 while keeping the video the same quality and a slightly lower filesize, as it should be?

  • 1
    When you choose match source - High Bitrate the name is a bit of a clue to the encoding settings: it's going to be using a high bitrate, so the file will be big. Match Source means matching the size, frame rate etc of the comp, not the original quality of one of the layers in the comp. Just wind down the video bitrate until you get to the size you want.
    – stib
    Sep 6, 2016 at 23:38

1 Answer 1


In general, it's better to work with lossless, or at least, less lossy formats than MP4 if you're going to be re-editing the video. If you can, work from a ProRes or Animation codec .mov file of the original file.

When you export, adjust the bitrate of the video by entering specific bit rate numbers... Vimeo suggests between 10,000-20,000kbps for HD video. Adjust it downwards until you get the output file size you want, but bear in mind the quality will reduce as the number goes down.

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