[BUG] Using Video Annotation FPS on image sequences defaults to -1

[BryonLewis]

Describe the bug If you upload an image annotation sequence and use the 'Video FPS" it will default to -1 for the FPS. Then when you try to use the playback in the image-sequence mode it won't play.

To Reproduce Steps to reproduce the behavior:

1. Upload image sequence
2. set FPS to "Video FPS"
3. Load dataset and hit the Play button or "Spacebar"
4. Not the console errors and that it doesn't play.

Expected behavior Default to at least "1" fps for video if the user chooses Video FPS

[waxlamp]

The default FPS should be closer to that of typical video files right?

[ghost]

The basics are it needs to >= 1: Other options are:

• We remove Video FPS from the importing tool when the data being imported are image sequences
• We allow people to change the FPS after upload through some new interface (this could cause problems based on stuff ran)
• On the server side when it is an image sequence and it is set to (-1) the number indicating it should be at the video FPS when importing videos. We should manually set it to 1.

I'm thinking that the best option is the first one, as well as a check in the back-end to make sure -1 is never finalized as an FPS for a dataset.