Video re-encoding compression datarates when publishing
Aug 23, 2013
When you import a video into Storyline using the "Video from file..." method, you browse to a video file and select it. Storyline then re-encodes the video (from numerous possible formats) into the standard MP4 video format (http://www.articulate.com/support/kb_article.php?product=st1&id=es3kzctg3aoq)
Does anybody know what the actual compression datarates that get applied to a video file when you publish your project? In the publish dialog box you can get at the Publish Quality window to adjust quality of video, audio and images. For video, this is a slider control that lets you select between 1 – 9. I'd like to know what compression datarates each of these quality increments apply. Without that, this is a simple (intentionally so), but abstract way to affect quality. From my perspective, I want to know how my already-compressed videos will be re-compressed/re-encoded.
Does each setting specify a single datarate? Is it variable? Is there a range, for example 1 = 250 kbps (kilobits per second) and 9 = 1,000 kbps?
I've found that using the highest setting, 9, will bring down videos that my team has already compressed for online use, by ~25%. While that's great as far as smaller sizes go, and the re-encoded video does look pretty nice still, I'd still like to know the "behind the scenes" details and how my videos are getting re-compressed.
I've found that, if one wants to, you can replace the Storyline-encoded videos in the "story_content" folder with your own pre-Storyline-encoded videos. It's a slow, manual work-around, especially when our courses might feature 20+ videos. Never mind the fact that you have to do this every time you publish a project, because the re-encoded videos in this folder get assigned unique, random names with each publish effort. With the way testing and client revisions can go on a large project, having to deal with this over the course of 10, 20+ re-publishings would be unmanageable.
For what it's worth, maybe the best approach is to keep this video setting at 9, and ask my video editors to provide me uncompressed videos - and then just let Storyline deal with it without the risk of compressing the same file twice. But with that comes the issue of uncompressed videos taking up lots more space on my hard drive than video editor compressed videos (which is how we handled it when producing courses using Flash).
I suppose a feature request one could make is to have these settings be actual datarates that you, the Storyline author, can see and tweak (similar to video editing or encoding software) where you just say what the target datarate is, from a possible min up to a possible max.