SL2 source file size & imported videos

I was finding that the file size of a *.story file was totally different than the MP4's video file size that I'd imported. The SL2 file is one slide, with just the video on the slide.

The video in this test example was 8.86 MB, and the resulting SL2 *.story file was, after saving it, only 1.48 MB. I'm familiar with the optional video quality settings in the publish window (using the "Video quality" slider from 1 - 9), but this isn't about file size post-publish, but about the *.story file size itself (which is independent of publish settings).

It seems like this: SL applies compression to any imported video. This video gets embedded into the binary format source file.  That makes sense for this kind of authoring tool since, if you imported 20 videos, they're all portable by one convenient source file. But I don't understand what's happening to my videos after importing.

Does SL truly apply  some level of pre-publish compression? What other reason would there be for the source file being a fraction of the video(s) inserted?

Is this compression lossless, leaving the re-compressing via publish settings up the the SL author?

My curiosity is more aroused when considering that SL2 now has an option to "Support uncompressed videos in published output". How can it be that an imported video could truly go through no SL compression when the *.story file is doing something to the videos

FWIW, I do find that inserted videos, and their published results, look quite fine! I'm also, despite my inquriy, REALLY happy that the *.story file is much smaller in file size than than if there was a 1:1 size ratio.

Thanks for any insight!

7 Replies
Scott L

Hi Ashley, I've attached the .story file and the MP4 video. The video is a 720p video, with custom compression specs from my video editor. I do wonder if the codec/format used can have an effect on this... I tried it again with a new SL2 file and had the same results.

Scott L

In a new test with a different video file (from a project three years ago), the results were what we would expect - a *.story file size (25.7 MB) that is just slightly larger than the MP4 video (25.6 MB). I'm guessing that this is related to how the video was compressed, and is a more typical situation. I'll try out other videos, too. However, I'm curious what you find, if anything, about my initial test files. Thanks!

Ashley Terwilliger

Thanks again Scott - I saw the same thing with your original video and files, and actually when I inserted it into a clean .story file I saw the file size as 1.50 MB, whereas yours was 1.49 MB. 

Storyline does support a number of codecs and profiles, and this one does seem to be working as expected. I'm glad to hear the published output meets your needs as well. 

Scott L

Indeed, when looking at the size of a file on a Windows machine, there tends to be 3 (slight) variations, depending on where you look. But it looks like you had the same result as me with the .story file being really small for this particular format/codec of a video. You don't speak to what might be happening, but it's probably just guess-work, anyways. Thanks for helping me understand what the typical file size effect if importing videos should be, though, Ashley!