We use the WebVTT HTML5 standard to create a thumbnail format that supports time synced thumbnail previews of your video that are displayed whenever users hover over the progress bar of their player. This is great feature for quickly scanning and navigating video content. Pair this with LongTail Video / JW Player and you'll find that the VTT output works perfectly with the new JW 6 Player's support of tooltip thumbnails.
Here's an great example from LongTail video on how to use this feature:
Add to your XML:
<?xml version="1.0"?> <query> <format> <use_vtt>yes</use_vtt> </format> </query>
There's a few other controls for VTT that are important to mention:
use_vtt — DEFAULT VALUE = NO
Join resulting thumbnails in single video tooltip thumbnail (VTT)
vtt_line_size — DEFAULT VALUE = 4
Set the count of thumbnails in line on VTT image
Please add these parameters for the thumbnail section of your API call. This will produce a single .vtt file with a default of 4 thumbnails in a row (adjust the vtt_line_size parameters to change from default), a default width of 120px (taken from the center of the video) and a default interval of 10 seconds.
Please view our complete API documentation here.