[kdenlive] [Bug 359160] 15.13.0 git master - Composite in tracks not working right when three (or more?) tracks are used. (Video example included)

[via KDE Bugzilla]

https://bugs.kde.org/show_bug.cgi?id=359160

--- Comment #15 from wegwerf-1-...@gmx.de ---
Can now reproduce render quality bug with transparent tracks when
semi-transparent text is used: https://bugs.kde.org/show_bug.cgi?id=359836

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[kdenlive] [Bug 359160] 15.13.0 git master - Composite in tracks not working right when three (or more?) tracks are used. (Video example included)

[via KDE Bugzilla]

https://bugs.kde.org/show_bug.cgi?id=359160

--- Comment #14 from wegwerf-1-...@gmx.de ---
Never mind, this seems to be an issue in my installation -- I could not
reproduce the problem. So please leave this bug closed-fixed. If I happen to
see any problems I can create a new bug that would be better anyway.

Jean-Baptiste, I join Jesse in his praise: this surely is an important Kdenlive
improvement that will help a lot of newcomers get around successfully in
Kdenlive.

>From a short glimpse at the code changes I grasped that my understanding seems
to be at least partly correct in that the "transition composition pipeline"
wasn't correctly set up: composition needs to happen to the "lowest" track and
not unconditionally with the next lower track. Did I understand this correct?

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[kdenlive] [Bug 359160] 15.13.0 git master - Composite in tracks not working right when three (or more?) tracks are used. (Video example included)

[via KDE Bugzilla]

https://bugs.kde.org/show_bug.cgi?id=359160

--- Comment #13 from wegwerf-1-...@gmx.de ---
Uhoh, please reopen this bug; while it works in principle, the results are not
smooth.

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[kdenlive] [Bug 359160] 15.13.0 git master - Composite in tracks not working right when three (or more?) tracks are used. (Video example included)

[via KDE Bugzilla]

https://bugs.kde.org/show_bug.cgi?id=359160

--- Comment #12 from wegwerf-1-...@gmx.de ---
Just tested it using an SVG inkscape clip on top video track, a Kdenlive title
clip on the middle track, and a video clip on the bottom video clip. It now
works correctly in principle.

However I notice that there is no proper anti-aliasing so that the text in the
SVG and title clips look very ragged and torn-out. To cross-check I've added
manual affine transitions that will result in proper smooth anti-aliasing the
SVG and title text onto the video clip.

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[kdenlive] [Bug 359160] 15.13.0 git master - Composite in tracks not working right when three (or more?) tracks are used. (Video example included)

[Jesse via KDE Bugzilla]

https://bugs.kde.org/show_bug.cgi?id=359160

Jesse  changed:

   What|Removed |Added

 Resolution|--- |FIXED
 Status|CONFIRMED   |RESOLVED

--- Comment #11 from Jesse  ---
Works way, WAY easier!!! No more need for the Affine transition or Composite
transition to apply alpha channels. Seriously, this will be a huge benefit to
the ease-of-use for users.

Thanks JB, you rock!

Marking this bug as resolved.

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[kdenlive] [Bug 359160] 15.13.0 git master - Composite in tracks not working right when three (or more?) tracks are used. (Video example included)

[Jean-Baptiste Mardelle via KDE Bugzilla]

https://bugs.kde.org/show_bug.cgi?id=359160

--- Comment #10 from Jean-Baptiste Mardelle  ---
Git commit ffae410dab837906843a77743eea1db4d7228bf1 by Jean-Baptiste Mardelle.
Committed on 26/02/2016 at 17:49.
Pushed by mardelle into branch 'master'.

Fix composite in multitrack

M  +7-18   src/doc/kdenlivedoc.cpp
M  +2-44   src/timeline/customtrackview.cpp
M  +1-3src/timeline/customtrackview.h
M  +20   -0src/timeline/timeline.cpp
M  +6-2src/timeline/timeline.h
M  +42   -1src/timeline/transitionhandler.cpp
M  +2-0src/timeline/transitionhandler.h

http://commits.kde.org/kdenlive/ffae410dab837906843a77743eea1db4d7228bf1

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[kdenlive] [Bug 359160] 15.13.0 git master - Composite in tracks not working right when three (or more?) tracks are used. (Video example included)

[Jesse via KDE Bugzilla]

https://bugs.kde.org/show_bug.cgi?id=359160

--- Comment #9 from Jesse  ---
Gratitude is all mine, JB. Thanks for considering this suggestion! I'm
confident that it'll make things much more user-friendly for a lot of editors
out there. :)

I look forward to making a video with a list of all the big improvements to
Kdenlive since the 15.12 release (and there have been many). We'll take the
majority marketshare of free-software video editors, yet!

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[kdenlive] [Bug 359160] 15.13.0 git master - Composite in tracks not working right when three (or more?) tracks are used. (Video example included)

[Jean-Baptiste Mardelle via KDE Bugzilla]

https://bugs.kde.org/show_bug.cgi?id=359160

Jean-Baptiste Mardelle  changed:

   What|Removed |Added

 Ever confirmed|0   |1
 Status|UNCONFIRMED |CONFIRMED

--- Comment #8 from Jean-Baptiste Mardelle  ---
Thanks Jesse for your investigation. I confirm and should be easy to behave
like Shotcut. Will work on it tonight.

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[kdenlive] [Bug 359160] 15.13.0 git master - Composite in tracks not working right when three (or more?) tracks are used. (Video example included)

[Jesse via KDE Bugzilla]

https://bugs.kde.org/show_bug.cgi?id=359160

Jesse  changed:

   What|Removed |Added

 CC||j...@kdenlive.org

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[kdenlive] [Bug 359160] 15.13.0 git master - Composite in tracks not working right when three (or more?) tracks are used. (Video example included)

[Jesse via KDE Bugzilla]

https://bugs.kde.org/show_bug.cgi?id=359160

--- Comment #7 from Jesse  ---
Well, I downloaded Shotcut and tested the same track tests as the project I was
working on in Kdenlive (I know that Dan D. heads up Shotcut and MLT, so I'm
assuming the projects are pretty tightly intertwined, and that Shotcut should
reflect what MLT can do).

I tried to perform the track composite functions, and they worked EXACTLY as I
thought they should, without issue. I've included a video to see what I'm
talking about: https://youtu.be/KjoPkPMmYbA

I had three tracks set up, a video clip on bottom, a black .png image in
middle, and a logo .png image with alpha channel on top. I was able to remove
the middle black image, and the video showed the logo on the top track, and the
video on the bottom without issue. I was able to manipulate the opacity and the
cropping of both the middle and top tracks without them affecting any of the
other tracks at all.

I'm going to assume that this means that MLT has the capability to do what I'm
suspecting it can. I'm going to suggest, like in the OP, that there's still a
bug in the composite function of the tracks themselves in Kdenlive. I expect
the compositing in all Kdenlive tracks - even the ones added - to behave like
they did in Shotcut; I shouldn't need an affine or composite transition anymore
to make these work properly (though, even when they're implemented, I still
can't achieve my goal with the track layers).

Can any of the dev's confirm this issue?

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[kdenlive] [Bug 359160] 15.13.0 git master - Composite in tracks not working right when three (or more?) tracks are used. (Video example included)

[Jesse via KDE Bugzilla]

https://bugs.kde.org/show_bug.cgi?id=359160

--- Comment #4 from Jesse  ---
Wegwerf, appreciate the explanation. So, is there anything that can be done to
remedy this? Many users will expect the function of tracks in the timeline to
be as I'd depicted above. I think it's GREAT that the dev's are implementing
this function, and when the time's right, maybe they can take a look at this
and see if it can be improved?

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[kdenlive] [Bug 359160] 15.13.0 git master - Composite in tracks not working right when three (or more?) tracks are used. (Video example included)

[via KDE Bugzilla]

https://bugs.kde.org/show_bug.cgi?id=359160

--- Comment #5 from wegwerf-1-...@gmx.de ---
Maybe discussing with Dan Dannedy of MLT fame first regarding handling of alpha
layers and the binary AND versus MIN operators?

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[kdenlive] [Bug 359160] 15.13.0 git master - Composite in tracks not working right when three (or more?) tracks are used. (Video example included)

[Jesse via KDE Bugzilla]

https://bugs.kde.org/show_bug.cgi?id=359160

--- Comment #6 from Jesse  ---
Will do, I'll see if I can contact him and correspond about the issue.

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[kdenlive] [Bug 359160] 15.13.0 git master - Composite in tracks not working right when three (or more?) tracks are used. (Video example included)

[via KDE Bugzilla]

https://bugs.kde.org/show_bug.cgi?id=359160

--- Comment #3 from wegwerf-1-...@gmx.de ---
Jesse, it does make sense.

However, the catch is in the handling of the alpha layer: ideally, this should
be a MIN(a,b) handling when compositing one clip with alpha layer onto another
clip also with alpha layer. Unfortunately, MLT doesn't support MIN, MAX, etc.
but instead only AND, OR, XOR. Now boolean operators only work for alpha when
there are exactly two alpha levels in use, namely 0 and 255. For gradual alpha,
as it is often used to achieve smooth blending, AND is not substitute for MIN.
The only way around this is to *not cascade* composition of multiple tracks,
one after another, but instead to all them composite only with the final,
bottommost layer. Only then alpha AND handling doesn't cause any problems. MLT
should support at least the MIN operator for alpha layer compositing...

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[kdenlive] [Bug 359160] 15.13.0 git master - Composite in tracks not working right when three (or more?) tracks are used. (Video example included)

[via KDE Bugzilla]

https://bugs.kde.org/show_bug.cgi?id=359160

wegwerf-1-...@gmx.de changed:

   What|Removed |Added

 CC||wegwerf-1-...@gmx.de

--- Comment #1 from wegwerf-1-...@gmx.de ---
I'm under the impression that this is a general problem with the transparent
track mechanism. You could verify this by switching all tracks to opaque and
then adding classic composite transitions to tracks 1 and 2. This should show
the same effect as you've shown in your video. I think that this comes due to
the fact that track 1 is composited with 2 ... and that's already wrong. It
should be composited to track 3 instead.

The existing transparent track mechanism could be fixed: for each transparent
track, find the nearest track below that's opaque. Only this will set up the
composition pipeline as intented. The current implementation isn't exactly
correct for three and more transparent tracks stacked onto each other. Maybe
the algorithm I outlined above can help?

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[kdenlive] [Bug 359160] 15.13.0 git master - Composite in tracks not working right when three (or more?) tracks are used. (Video example included)

[Jesse via KDE Bugzilla]

https://bugs.kde.org/show_bug.cgi?id=359160

--- Comment #2 from Jesse  ---
Ideally, in a perfect video editing world, the timeline tracks would behave
like so:

VIDEO TRACK 3 --[|||]-
VIDEO TRACK 2 ---[|||]-
VIDEO TRACK 1 [|]---

([||] = a clip in the timeline)

If a video clip is on track 1, and track 2 has a clip above it with an alpha
channel, then the transparency portion of that clip would show the clip below
it on Track 1. Similarly, if there was a video clip on track 3, two tracks
above the video clip on track 1, the alpha transparency from the video clip on
track 3 would show the video clip on track 1. This would happen automatically.

In other words, If there is a video clip in the timeline with an alpha channel,
the transparency part would show the clip beneath it, regardless of how many
tracks below the clip in question is on.

Hope that makes sense. :/

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[kdenlive] [Bug 359160] 15.13.0 git master - Composite in tracks not working right when three (or more?) tracks are used. (Video example included)

[Jesse via KDE Bugzilla]

https://bugs.kde.org/show_bug.cgi?id=359160

Jesse  changed:

   What|Removed |Added

URL|https://youtu.be/f5QiCwO1cB |
   |o   |

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[kdenlive] [Bug 359160] 15.13.0 git master - Composite in tracks not working right when three (or more?) tracks are used. (Video example included)

[Jesse via KDE Bugzilla]

https://bugs.kde.org/show_bug.cgi?id=359160

Jesse  changed:

   What|Removed |Added

URL||https://youtu.be/yHfh1ul9b_
   ||o

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[kdenlive] [Bug 359160] 15.13.0 git master - Composite in tracks not working right when three (or more?) tracks are used. (Video example included)

[Jesse via KDE Bugzilla]

https://bugs.kde.org/show_bug.cgi?id=359160

Jesse  changed:

   What|Removed |Added

URL||https://youtu.be/f5QiCwO1cB
   ||o
 CC||jesse.dub...@gmail.com

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