For me it also makes a difference and it should be put into the manual for sure as a possibility on some computers. I assume it is based on the speed to get to the disks?? And there is probably a "sweet spot" for anyone's specific system.
Here are my observations but not totally scientific based on 64-bit Fedora 31/32.
Input File: Big Buck Bunny with Video Effect brightness/contrast applied; Play every frame enabled (I got different results when not Play every frame).
HP slow laptop Forward Framerate Achieved = 32 for .5, 1.0, and 2.0 seconds.
0.5 seconds Reverse Framerate Achieved average = 15 and varied from a low of 9 to a high of 18
1.0 seconds Reverse Framerate Achieved average = 18 and varied from a low of 15 to a high of 23 -- playing seemed moe consistent
2.0 seconds Reverse Framerate Achieved average = 17 and varied from a low of 13 to a high of 23
AMD gaming laptop Forward Framerate Achieved = 60 for .5, 1.0 and 2.0 seconds.
0.5 seconds Reverse Framerate Achieved average = 32 and varied from a low of 19 to a high of 40
1.0 seconds Reverse Framerate Achieved average = 36 and varied from a low of 28 to a high of 42 -- playing seemed moe consistent
2.0 seconds Reverse Framerate Achieved average = 35 and varied from a low of 30 to a high of 43
One thing that has always bothered me is that in the transition from
an 11 year old notebook to a mid-to-high level PC, playback and
especially reverse playback always suffered from the same lags and
framerate drops. There wasn't the improvement I expected. In the
Preferences > Performance tab, I tried increasing the "Cache size"
from 256MB (default) to 4096MB without noticing any change (I have
32GB of RAM). I never touched the "Seconds to preroll renders" option,
which by default is 0.5 seconds. Now I've tried to set it to 1.0s and
the improvement in playback and reverse playback is EVIDENT!
If anyone feels like trying to take a problematic project in timeline
and increase the preroll time and then report the results, it would be
a favor to me. If the improvement is also confirmed by others I will
immediately put the tip in the manual, because it seems very important
to me.
--
Cin mailing list
Cin@lists.cinelerra-gg.org
https://lists.cinelerra-gg.org/mailman/listinfo/cin