Controlling Playback Speed

[davemason]

Hello All,

We use our OMERO.gallery to host supporting data for papers/projects/theses etc. Lately there have been a lot of timeseries uploaded, some that make sense at lower frame rate and some at higher.

I found the "Movie" options in OMERO.insight, but the FPS box seems to have no bearing on the playback speed (testing from 1fps -> 30fps). I though this was a problem with uploaded AVI files but it happens with TIFF stacks too.

Questions!
1) Is this feature fully implemented? Is there some way to get at it from OMERO.web?
2) If set, would you expect the playback speed set in insight also apply to images played through the OMERO.gallery interface (which as I understand it is effectively a full viewer).

Many thanks as ever,

Dave

[wmoore]

Hi Dave,

I'm afraid this feature is only in Insight and the playback speed is not saved to OMERO.
We only store the timestamp info of the original acquisition (if it's in the original file and is read by Bio-Formats) but there's no concept of a playback speed for viewing.

In the web viewer, it's harder to set a playback speed because each plane is requested as needed and the time until it's shown will be dependent on network speed.
It may be possible to set a minimum delay on each frame, so that the playback could be slowed down below the limits of network speed.
But this could be a fair bit of investigation & work, since you'd wouldn't want to wait for playback delay and *then* start loading the frame, since that would give an extra (variable) delay.
You'd want to start loading the frame by setting the src of an Image, but then not have that image displayed as soon as the network responds. So, you'd need a hidden Image for loading, separate from the display Image. Sorry - that sounds confusing, but the summary is that it's not a trivial feature.

This is one of the problems I had in mind when working on a couple of prototypes that load all the image data up-front, so you have all the data in hand.
You can see one simple example at http://codepen.io/will-moore/pen/Beuyc (mouse-wheel to scroll through Z)
and a more extensive example (but still early days) is at https://github.com/openmicroscopy/webtest/pull/11

However, I'm afraid this functionality is still at the investigation stage and is not scheduled for production/release.

We'll look into the Insight playback bug.
Sorry I couldn't be more help.

Regards,

Will.

[davemason]

Thanks for the quick reply. It's a shame that it's not easier to implement, but at least I now better understand the difficulty.

Pre-caching is an interesting idea, but I don't know how huge datasets be handled. I will definitely have a look at the links you sent.

All the best,

Dave