I’ve been using a Mac more and I’ve noticed that the mp4 files generated by Camtasia on the mac are much bigger than those generated on the PC.

A recent conference talk recording was output at 5.74 gig which meant I couldn’t upload on my Vimeo plan so I had to find a way to compress the file.

This doesn’t make that much difference to me usually since hard drive space is cheap, YouTube doesn’t care, online course hosts tend to reprocess your video and shrink it anyway. But I needed this file on Vimeo to share with my Patreon group.

Camtasia recommend changing dimensions, frame rate and data rate.

support.techsmith.com/hc/en-us/articles/203727328-Camtasia-Mac-How-to-Make-the-File-Size-of-Videos-Smaller

But the time it takes to experiment with different settings didn’t seem worth it.

I found the following code and comments on gist

ffmpeg -i original.mp4 -vcodec h264 -acodec aac compressed.mp4

This brought a 6 gig file down to 650 mb.

I could spot no obvious quality degradation and so this is now a standard part of my mac video production workflow.

You do have to install FFMpeg but this is free, cross platform and open source.

What does this command do?

• -i original.mp4 use original.mp4 file as input
• -vcodec h264 use the video codec h264
• -acodec aac use the aac audio codec (could also be mp3)
• compressed.mp4

I had to use aac otherwise there was no audio in the output file.

What is ‘odd’ is that the original file was encoded with H.264 and AAc audio. The most obvious difference I can see from the output files is that the compressed file does not have a color profile listed. The ’large’ file has a Color Profile of (HD 1-1-1).

It is possible that the video and audio encoding efficiency of ffmpeg is simply better than Camtasia.

This will work on Mac, Window or Linux and although it does take time, the saving in storage and upload time is probably worth it.