Why are MP4 files produced by Camtasia 3 so much larger than those produced by Camtasia 2?

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  • Updated 6 months ago
I recently upgraded from Camtasia 2 for Mac to Camtasia 3 for Mac. Needing to work on an existing project, I converted a Camtasia 2 file to work with Camtasia 3. Everything seemed to go well. I only made a couple of changes and saved the file, then exported it to MP4 format.

Both versions of the Camtasia file are the same size, 179.4 MB. The changes I made weren't enough to increase the file size. But the MP4 I created from the converted Camtasia 3 file is many times larger than the MP4 I had created from the Camtasia 2 version of this same project.

The Camtasia 2 MP4 is 354.3 MB, while the Camtasia 3 MP4 is 1.17 GB! That 3.3 times larger.

That seems very crazy. I did see a post from TechSmith wherein you expressed awareness that Camtasia for Mac MP4s have a larger file size than those produced by Camtasia for Windows, but look at the difference between MP4 produced by two different versions of Camtasia for Mac.

Why is this?
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KarenA

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Posted 6 months ago

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KarenA

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I'd really like to hear from TechSmith on this. 
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kevinohlson

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The size of mp4 files is the result of input settings to the encoding (sharing/exporting) process. In Camtasia 2,  if I recall correctly, encoding went through Quicktime 7 (transparently). Apple directed developers to switch away from this, as it was being deprecated. Camtasia created their own encoder, and the default settings create large(r) files. Earlier versions of C3 weren't configurable, but more recent versions have enough options in Share-Local File-Options menu to configure smaller files.
Encoding and compression can get really complicated. I'm a big fan of Handbrake (which requires VLC - both free). It's an extra step but does an great job of reducing file size without reducing quality. 
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Paul Middlin, Employee

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Hi,
You're right- we have been looking into this and the default settings that come in Apple's encoder here create files that, while they look good, are very large. We'll be making some changes to those defaults in a future release, but in the mean time, this is what we'd recommend:
When you export, go into the options, and choose "custom" for the video bit rate. Choose a number somewhere between 2000 and 3000. It would be good to experiment with this a little to make sure you are happy with the quality of the video that is produced to find something just right for your content. But, anything in that range should be significantly smaller.
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KarenA

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Thank you.
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davemillman

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So a year or two before 3.X was released we were complaining that Techsmith had removed the ability for us to reduce the compression on our output files in order to maximize quality (and correspondingly bloat the output files!). Eventually we got control back, for which we are happy.

If you need smaller files, experiment with these sliders in the Share Options window. You probably want to do the experiments on a 5-second clip, so you can try a lot of variations in a shorter period of time. Start with Data Rate, you may not need to go further. Try keyframe rate next (1 works with most content). Don't take frame rate below 15FPS unless your content is rather static.



And finally, if you are going to upload to YouTube or Vimeo or similar, DON'T REDUCE THE OUTPUT FILE SIZE AT ALL! Export and upload the largest possible, gigabytes if necessary. The reason is that compression and encoding and resizing are complex, and YouTube and Vimeo do it better than anyone, and they will create 6 optimized sizes automatically.
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Paul Middlin, Employee

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Good advice. I'm not sure if you meant to set "keyframe rate" to 1, though? That tells it to do a keyframe on every single frame, which would make your output very large. You could *increase* this to save some file size, but it makes seeking around within during playback slower (the player has to 'work harder' to calculate what each frame is supposed to look like when you jump around). That's presuming you're watching the original video, and not a re-encoded one (on youtube/vimeo), which would probably set this back to 30 or lower.
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davemillman

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You're right about keyframes, I wrote it backwards. How come we can't edit our own comments?
(Edited)