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Strange issue with webm files (with possible temporary fix)

July 13 (3 years ago)
Peter's Forge
Pro
Marketplace Creator

 Hi,

 So I have been working on an item that includes animated icons and run into a strange issue. While testing I noticed some .webm files are not loading while refreshing the page. This happens randomly to different files each time and reloading the web page may bring back the ones that were gone before. Initially, I assumed it was something I was doing wrong with the animated art files but after extensive testing I can confidently say it seems to be an internal Roll20 engine issue. Here is what I managed to establish:

 1.) The issue occurs only when animated files are involved and only affects .webm files.
 2.) Files disappear regardless of file size, frame count, naming, colors, transparency level, resolution(!), compression method, software used to create them,
    (I brought down file sizes to below 15 kb using every method I could think of and issue still occurred. Poorly compressed/made files behave just as the better ones in this regard)
3.) The amount of .webm files on a page directly affects the rate and intensity of files not loading. Total item count has greater effect than total item size.
   (20 animated tokens 15 kb each disappear more often than 10 animated tokens 500 kb each)
4.) Having the items currently looping or not does not seem to have an impact.
5.) The layer the .webm files are on don't seem to have an impact (map/token/GM).
6.) Loading the files from personal library or marketplace library don't seem to have an impact (from a draft).
7.) Type of grid used is somehow a factor. Maps with square grid have this issue noticeably more often than ones with a hex grid. 
8.) Marking animated tokens as 'Is Drawing' has major impact on disappearing rate and intensity. To a point of almost eliminating it when concurrent file count on page is below 20.

 I made around 30 tests for each of the above situations. Overall the loading problem was pretty consistent with at least 50% of all page refreshes resulting in at least one .webm not loading correctly. Obviously a more in-depth test by someone with proper knowledge of the engine is probably needed. Best I can tell the issue seem to be most pronounced when the engine tries to load the animated files and fix them to a grid scaling them appropriately. Grid type and snapping was where I noticed the biggest improvement. If I were to guess this is the area I'd look first for a working solution. Hope it helps.

 As for Roll20 users, a temporary solution might be keeping concurrent animated file count on a page to below 15 and marking each .webm as 'Is Drawing' (right click on the file->Advanced->Is Drawing). Using a hex grid (if your game allows it) can hep further, or if impossible turning off the grid.  

July 13 (3 years ago)
keithcurtis
Forum Champion
Marketplace Creator
API Scripter

Great research! Points 7 and 8 may be invaluable to a lot of users, as I don't think that animation was announced as one of the development pushes this year.

I test a lot of webm tokens for our patreon and have definitely experienced this, along with webm transparancy failing to display and transparent pixels rendering as black.