Let's add little more context. Currently things are getting more stable and we are starting to see the new lot of problems coming. One of the problem is performance. Currently it is really quick to reach the state where relativly fast computer can't handle the editing in real time.

An example was to add an AgingTV effect on top of a 720p video. That would immediatly start loosing frame. From profiling result, video convertion from i420 to RGBA seems to be the bottleneck, and there might be an issue there also to consider.

Though, in the longer term, to be able to stay real-time in our previews, we should experiment with potential solutions. The enclose ide here is a suggestion and I think should be evaluated. A more drastic solution would be using proxied scaled down form of the videos, though would introduce some delays to the user experience.

I think it is now mostly done, we scale down video using the project setting right at the end of sources, we might just want to be smarter and scale to something else (not sure what computation should be done there tbh) when in preview mode though.

(In reply to comment #2)
> I think it is now mostly done, we scale down video using the project setting
> right at the end of sources, we might just want to be smarter and scale to
> something else (not sure what computation should be done there tbh) when in
> preview mode though.

Do you mean PiTiVi could already handle it? I think the simpliest would be to define a maximum size, to witch we consider represent low-res, (keeping the configured aspect ratio configured for rendering). Though, I think Jeff told me we might also need to configure a switch, so user can display full quality for fine tuning of effects like, let's say sharppening. I guess this mean we might need to agree on UI first.

Hope that make sense !

Just for the record and in the interest of anyone looking at this bug report to tackle the issue of "dynamically downsizing to the dimensions of the viewer widget to gain even more performance": I think that what Thibault is referring to in comment #2 is the "restriction-caps" property of GESTrack.

I have a branch here that I would like help and feedback on:
https://github.com/nekohayo/pitivi/commits/low-quality-preview

It seems to work but currently:
- It's rather easy to hit segfaults by undocking the viewer
  and resizing it in various ways
- Restriction caps don't reset to the project settings' on rendering

This bug has been migrated to https://phabricator.freedesktop.org/T2032.

Please use the Phabricator interface to report further bugs by creating a task and associating it with Project: Pitivi.

See http://wiki.pitivi.org/wiki/Bug_reporting for details.