Walkthrough tips (video encoding)
A colleague from another branch office asked me to research walkthroughs for him, as I'm about four years more experienced with Revit. I guess that making the walkthrough shouldnt be much of a problem for anyone reading this topic (in case I'm wrong: questions are welcome below this post).
Instead I focused on creating a workable video. Basically what I did was drag the crop region to pretty much two or three times it's width to about 1000-1200px and height to about widescreen ratio (preferably a bit less, to be safe but if it's more we're going to fix that in a later step). The perspective should just about look convincing now, rather than looking through the narrow confines of a camera.
I exported to uncompressed format and ended up with a 20 second video of about 600-700MB. The filesize is a problem for two reasons: first is it's not easy to share. Second, playback will be choppy due to data transfer. And even then, the default 15fps isnt completely smooth.
So I made another attempt. Set framerate to 24 (which is PAL standard, NTCS should be 25 or 25.5 if I remember it right) and recalculated the number of frames from 300 to 480.
The filesize ended up being about 1000MB. Playing back 50MB/sec would stress most computers, let alone a typical laptop for presentation. And this is just a 20 second video! I realized the codec was the problem. I tried looking for (and installing) new codecs but no luck; if it's possible it's quite fiddly.
How about AVI conversion software you might ask, like I did. So i did some research and remembered a rather good program called AVI Recomp (posting a link would be spamming but look it up). This is where it gets interesting.
AVI Recomp is free software (I think under the GNU license) and in my experience contains no spyware or adware. I found it very convenient for cropping the exported video to get rid of that stupid white frame, (52px l+r, 28px t+b) and if it ended up being higher than widescreen ratio (16:9) you can also fix that here. You could also add audio and subtitles (if you want to add description; I havent researched how to make a subtitle file) and insert your company logo (must be a full colour bitmap file).
But the greatest benefit comes when you put the program to work. It recodes the video to divx in less than a minute (might take longer when adding logo, audio and subs), resulting in a file of only 16MB (again not counting audio). This makes the file much more portable and smoother for any purpose. Quality does not seem to suffer at all.
In summary:
- Make your walkthrough and finetune until you drop.
- Drag the crop region to where you think it represents a realistic perspective. I ended up making it about two times wider and a bit higher.
- Recalculate the walkthrough from the default framerate to 24 or 25 frames/sec (whichever makes more sense to you).
- Export uncompressed to your local harddrive (quicker than network or USB storage as each frame needs to be written to a file).
- Some would suggest segmenting longer walkthroughs into ten second chunks and stitch them together later.
- Post-process the video in another program, ie Adobe Premiere, AVI Recomp or an Autodesk product for this purpose to add sound, logo, description, maybe some effects or adjust image quality, etc.
- Export to a smaller avi file (divx for example) and it's ready for consumption!
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