Bug 441051

Summary:	Video Glitching out when running the slowed down area of Time Remapping
Product:	[Applications] kdenlive	Reporter:	Jim <JamesIChristman>
Component:	Translation	Assignee:	Vincent PINON <vpinon>
Status:	RESOLVED FIXED
Severity:	normal	CC:	fabian, fritzibaby
Priority:	NOR	Flags:	fritzibaby: Brainstorm+
Version First Reported In:	21.08.0
Target Milestone:	---
Platform:	Other
OS:	Microsoft Windows
Latest Commit:		Version Fixed/Implemented In:	21.08.1
Sentry Crash Report:

Description Jim 2021-08-16 16:41:15 UTC

SUMMARY
Rendered video glitches out when going from normal to slowed down. More so in higher Res 4k but also in 1080 both 29.97fps. When paused picture is either 1/4 sized or normal but when playing it flicker and line across screen but only in the slow down portion.

STEPS TO REPRODUCE
1. Created a short clip in 4k 29.97
2. Dropped down to 1080 29.97
3. 

OBSERVED RESULT
 Replaying in VLC and 

EXPECTED RESULT
smooth transition

SOFTWARE/OS VERSIONS
Windows: 10.0.19043 16G i9-9880H HP Zbook note book
macOS: 
Linux/KDE Plasma: 
(available in About System)
KDE Plasma Version: 
KDE Frameworks Version: 
Qt Version: 

ADDITIONAL INFORMATION See attached Images.

Comment 1 Jim 2021-08-16 16:53:45 UTC

See image of https://img.gg/2hP9znk

Comment 2 Jim 2021-08-17 19:37:12 UTC

Video of see: https://img.gg/369qI0Z

Comment 3 fschuiki 2021-08-22 14:01:51 UTC

I can confirm that I also see this issue. Using 4K 29.97 Hz footage (in 30 Hz project), I see one glitch frame at the boundary between a sped-up section and a 100% speed section, without frame blending. With frame blending, I get lots of glitches in the 100% section.

Comment 4 fschuiki 2021-08-22 15:42:23 UTC

Further observation: Enabling frame blending creates a result where glitches and actual frames are average, which suggests that the problem occurs before time remapping in the pipeline. Could be related to MLT, and how the timeremap reads data from the thing before itself (https://github.com/mltframework/mlt/blob/04bd9ff25670c9986b8de016b73b9f483dabc9fc/src/modules/core/link_timeremap.c#L243-L316).

Comment 5 emohr 2021-08-24 15:19:56 UTC

Thank you for reporting. I tested with a 4K 59.9401fps clip but I don't have this glitches. @fabian@schuiki.ch do you think your MLT commit fixes the issue (https://github.com/mltframework/mlt/commit/685698ab01fea2ac5322ab074b3e827ead5a6739)?

Comment 6 fschuiki 2021-08-24 16:57:29 UTC

@emohr It fixed the issue for me, and it looked like the bug I was seeing was the same as what @Jim saw. I'm hopeful this is fixed now.

Comment 7 Jim 2021-08-26 12:03:33 UTC

Is this fix in Daily kdenlive-master-865-windows-mingw_64-gcc.7z if so I'm still seeing the same issue.

Comment 8 emohr 2021-08-26 14:56:20 UTC

@Jim. This is not fixed in the daily build, as we have to push the MLT master first. I let you know when it's done.

Comment 9 emohr 2021-08-27 15:02:11 UTC

@Jim. MLT master pushed. The latest MLT fix should be in the nightly build. Please try, if it's not working try tomorrow.

Comment 10 Jim 2021-08-28 14:50:08 UTC

Looks good that did the trick. Thanks for fixing that.

Comment 11 emohr 2021-08-28 16:17:21 UTC

Thank you for the feedback and contribution. Glad to hear it works.