Why is seek absolute (with hr-seek=no) slower than (relative) seek

[tbertels]

With mpv.conf: hr-seek=no
When for instance at the start of the file (position 0) and we do either:

• seek 120
• seek 120 absolute

mpv seeks to the same position (closest keyframe after 120).
But seek 120 is faster.

This is especially noticeable when using a second instance of mpv for the video preview on the seekbar, like we do for MPC-QT, because it requires very fast seeking.
You can compare:

• the latest release which uses time-pos¹ with hr-seek=no
• the latest dev-build which uses relative seeking.

The video preview is faster with the dev build. But it's much more complicated (and still bugged) than absolute seeking..

I would expect mpv to be able use the same algorithm (and be as fast) for absolute seeking as for relative seeking.
Is there a reason it isn't so? And is it something which could get improved in the future?

Footnotes

1. I've tested with seek absolute instead of time-pos and if anything it was actually slower. ↩

[guidocella]

seek 120 absolute+keyframes

[tbertels]

I did try with it before, but maybe I spelled it wrong (without the s).
Anyway, it does seek as fast as with relative seeks.
Thanks!