Problem definition

It seems that in order to perform frame-by-frame navigation with the A and D keys, frames have to be buffered already. When navigating to some point in the clip(s) with the mouse or any of the key-shortcuts, the buffer is empty, so frame-by-frame navigation isn't possible. In order to get the frame navigation to work, the user has to use the following cumbersome process:

1. Find interesting spots in the clips to be analyzed by jumping around with the available seek-options.
2. Once a spot has been found, jump back one keyframe (e.g. - key).
3. Press play until the buffer fills up to 50 frames, and be quick on the trigger to pause the video.
4. Navigate back with the A key until the specific frame of interest is found.

Proposed improvement

Get rid of steps 2-4 by either:

• A) Optimal UX: buffering the surrounding frames automatically. E.g. 25 frames on each side and have the code re-buffer automatically if frame navigation reaches either end of the buffer (buffer position 0 or (left|right)_frames.size()-1)
• B) OK UX: providing two new key shortcuts (e.g. shift-A & shift-D) that the user can trigger to automate step 2-3 above. I.e. seek backward one key-frame and then decode the frames up until the current position. Similarly for forward buffering where the buffering would work exactly like playing for 50 frames, with the exception that the views get rendered from the first item in the buffer. I.e. the same as performing steps 2-4 above, and navigating all the way back to the beginning of the buffer using the A key.

With option A, the user could navigate the entire clip frame-by-frame seamlessly.
With option B, they'd have to buffer manually, but would still allow pretty much uninterrupted workflow with just one extra key to press every now and then.

The reason I even mentioned option B was that after looking at the code, it might be easier to implement. Whatever improvement can be done in terms of frame-by-frame navigation would be greatly appreciated.

PS. fantastic tool. Just discovered it and am kicking myself for not finding it sooner.