How to reproduce from scratch:
1) create a new image strip (e.g. a sequence of images from 1 to 10)
2) set the sequence blend to replace
3) animate the sequence opacity to be 0.0 in the begin, and 1.0 in the end
4) create a metastrip with this sequence
5) with the metastrip selected go in the filter panel and select "backwards"
What I expect to see: the final "internal frame" (meaning image * opacity) to be reversed (so images would go from 10 - 1 and the internal opacity from 1.0 to 0.0)
What do I see: only the images are reversed (going from 10 to 1), but the opacity is still going from 0.0 to 1.0
See sequencer_backwards.zip test file
Its has 4 strips:
(1) normal sequence
(2) metastrip (normal sequence) with backwards
(3) normal sequence with animated opacity
(4) metastrip(normal sequence with animated opacity) with backwards
Description
Event Timeline
This is actually expected behavior of backwards filter and it's hard to solve in a way you expect it to work. In a pipeline animation data is calculated before sequencer starts rendering strips and sequencer assumes all the values are set to proper value by animsys. So sequencer could easily reverse order of frame in image sequence/movie strips but it can not inverse animation applied on this strips. It could be hacked in a way sequencer will change current frame and re-calculate animation data, but it'll break editing of animated properties (as it was broken by quick cache and how it's broken by scene strips when sequencer preview is opened).
This change will also backfire on user interaction level -- you wouldn't see actual values of opacity in graph editor and strip properties.
So thanks for the report, but i would say it's not going to be changed since it's really can of worms and faces design limitations.
It's sad to hear that. The current limitation is really limiting (and misleading in a way).
For the records, this is what I have to resort to in order to get the sequence reverted.
cd folder_with_sequence;mkdir ../folder_with_reversed_sequence;array=();for i in *;do array=( "$i" "${array[@]}");done; c=1; for i in ${array[@]}; do k="../folder_with_reversed_sequence/"`echo $(printf "%.4d" "$c")`".png";c=`echo $(($c+1))`; echo "cp "$i" "$k""; cp `echo "$i"` `echo "$k"`;done