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I'm trying to use Ubuntu Linux 19.04 to convert an OpenShot video into a more efficient file-size.

The video only contains two still images, and 20 minutes of audio, but for each file-type I save-as, the output-file is larger than 600MB.

Apparently I'm choosing the wrong lossless output file-type; you'd think a video like this would only be 10MB, since almost all the frames, in the entire video, are one of two frames.

Using ffmpeg, how can I convert this video to a format that understands how to compress all the duplicate frames efficiently?

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Your question is answered in the ffmpeg examples. You can use something like this:

ffmpeg -loop 1 -framerate 1 -i banner.png -i audio.wav -map 0 -map 1 -c:v libx264 -crf 16 -c:a aac -b:a 92k -shortest -movflags +faststart ready_to_upload.mp4

Detailed explanation:

  • -loop 1 repeat image potentially forever
  • -framerate 1 have a low frame-rate
  • -i banner.png -i audio.wav input image and audio
  • -map 0 -map 1 use both stream
  • -c:v libx264 -crf 16 have high-quality image
  • -c:a libfdk_aac -b:a 92k have high-quality
  • -shortest stop repeating banner image when audio is finished
  • -movflags +faststart include index at beginning of MP4 container for early start

It compresses to approximately 1 MB per minute.

Note: YouTube is likely (but not guaranteed) to re-encode your video. Image quality will degrade.

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  • Sorry, my mistake, there are actually two images in the video. The image changes near the end. – Lonniebiz Aug 10 '19 at 23:10
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    Same thing, do two videos, one for each image, and concatenate them... – xenoid Aug 10 '19 at 23:17

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