Bug 415146 - Rendering produces produces black_track producer, black frames at end
Summary: Rendering produces produces black_track producer, black frames at end
Status: RESOLVED WORKSFORME
Alias: None
Product: kdenlive
Classification: Applications
Component: Rendering & Export (show other bugs)
Version: 19.08.3
Platform: Microsoft Windows Microsoft Windows
: NOR normal
Target Milestone: ---
Assignee: Jean-Baptiste Mardelle
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2019-12-13 17:47 UTC by Nathanael Komline
Modified: 2020-10-14 04:33 UTC (History)
2 users (show)

See Also:
Latest Commit:
Version Fixed In:
Sentry Crash Report:
fritzibaby: timeline_corruption+


Attachments

Note You need to log in before you can comment on or make changes to this bug.
Description Nathanael Komline 2019-12-13 17:47:59 UTC
Rendering produces a long black track, about 19:00 in length. It appears to be generated as part of the .mlt for an unclear reason.


STEPS TO REPRODUCE
1. Render a video

Video is 19:01 no matter what the selected duration is.

SOFTWARE/OS VERSIONS
Windows: Windows 7

If you choose ‘Generate Script’, you can find a producer with id=“black_track” which appears to be the culprit. If you comment out this producer and references to it, then run the script in Kdenlive, the video renders correctly.
Comment 1 Nathanael Komline 2019-12-13 17:49:54 UTC
I forgot to mention that the final video is rendered correctly, just with a long section of black frames at the end.
Comment 2 emohr 2019-12-20 16:30:08 UTC
First, try with version 19.12. Please describe step by step what you doing before you hit the render button. 

Do you enable "selected zone" before you render? 
How do you have done the script?
Comment 3 ahiijny 2020-02-15 23:35:37 UTC
My setup:

Kdenlive Version 19.12.2
Using: MLT version 6.19.0
KDE Frameworks 5.66.0
Qt 5.14.0 (built against 5.14.0)
The windows windowing system

Windows 10

I think I'm seeing this too. Whenever I render something, the output video is way longer than I expect. The output video has all of my expected content, but also a very long segment of black nothingness at the end that I don't want. This happens both when I select "Full project" or if I select "Selected zone" in the "Rendering - Kdenlive" (after stretching the selected zone blue bar thing in the timeline to cover the content part of the timeline).

To reproduce:

1. Start a new project (e.g. HD 720p 23.98 fps)
2. Drag a video from your filesystem into the project bin (e.g. a 32-second mp4 video file.)
3. Drag the clip from the project bin into the timeline. 
4. Render. (The settings probably don't matter, but I have it set to MP4, quality: video = 30, audio = 192, Full project, More options > Encoder speed > the highest/rightmost setting, More options > Threads > 1)

Observations:
1. This takes way longer to render than I'd expect of a short 32-second clip (4 minutes 30 seconds).
2. The output video is 21 minutes 23 seconds long.
3. The output video contains the 32-second video content, followed by 20 minutes 51 seconds of blackness.
4. If I open the kdenlive save file, I notice there's a line of text with "<producer id="black_track" in="00:00:00.000" out="00:21:23.315">", which happens to be exactly the same length as the erroneously long output video.

Additional note:

I have older kdenlive save files that I created with an earlier version of Kdenlive, version 19.08.1. These save files also have a "black_track" producer on the order of 20-some minutes. But they rendered just fine back with the older version of Kdenlive. But when I open up these same save files with v19.12.2 and render, the output is erroneously long, with the overly lengthy black frames at the end.

So, did something change about the rendering process? Behaviour-wise, I'd expect the renderer to truncate the output after the end of the last clip on the timeline, so that you don't have long empty stretches of black frames at the end of the video.
Comment 4 emohr 2020-09-12 18:20:18 UTC
Rendering issues on Windows should be fixed. Please try with version 20.08.1.
Comment 5 ahiijny 2020-09-14 21:36:16 UTC
Kdenlive Version 20.08.1
Windows 10

(I installed the standalone version of 20.08.1, so I think it conflicted a bit with my existing installation of version 19.08.1. Got a 'qt.qpa.plugin: Could not load the Qt platform plugin "windows" in "" even though it was found.' error, but things rendered properly after I clicked Help > Reset configuration).

Seems to work fine now.

I opened up the test project I made for this bug and rendered it. Output video length is now the correct 32 seconds, not the erroneous 21 minutes 23 seconds it was when I rendered it with 19.12.2.
Comment 6 Bug Janitor Service 2020-09-29 04:33:12 UTC
Dear Bug Submitter,

This bug has been in NEEDSINFO status with no change for at least
15 days. Please provide the requested information as soon as
possible and set the bug status as REPORTED. Due to regular bug
tracker maintenance, if the bug is still in NEEDSINFO status with
no change in 30 days the bug will be closed as RESOLVED > WORKSFORME
due to lack of needed information.

For more information about our bug triaging procedures please read the
wiki located here:
https://community.kde.org/Guidelines_and_HOWTOs/Bug_triaging

If you have already provided the requested information, please
mark the bug as REPORTED so that the KDE team knows that the bug is
ready to be confirmed.

Thank you for helping us make KDE software even better for everyone!
Comment 7 Bug Janitor Service 2020-10-14 04:33:36 UTC
This bug has been in NEEDSINFO status with no change for at least
30 days. The bug is now closed as RESOLVED > WORKSFORME
due to lack of needed information.

For more information about our bug triaging procedures please read the
wiki located here:
https://community.kde.org/Guidelines_and_HOWTOs/Bug_triaging

Thank you for helping us make KDE software even better for everyone!