OpenShot
video preview does not play or freezes
With .mkv files written by X-media recode the video preview is not displayed (black) or freezes on a still image MKV - codec is V-MPEG4/ISO/AVC
Load an .mkv video Place it on Track 1 Play preview
The same video as .mp4 (avc1) plays ok. Other videos .avi (xVid) play ok.
Expected behavior Video plays
System Details
- OpenShot Version: 3.4.0
- libopenshot Version: 0.5.0
- Platform: Windows-10-10.0.22621 (Windows 11)
- Processor: Intel64 Family 6 Model 94 Stepping 3, GenuineIntel
- Machine: AMD64
- Python version: 3.8.9
- Qt5 version: 5.15.2
- PyQt5 version: 5.15.4
- Qt Detected Languages: ['fr-FR', 'en-US']
- LANG Environment Variable:
- LOCALE Environment Variable:
- Daily Build: Verified issue still exists in daily build: http://github.com/OpenShot/openshot-qt/releases/download/OpenShot-v3.4.0-release-candidate-13919-c6720bb5-0b018e34-x86_64.exe
Log Files
- openshot-qt.log (5 KB)
- libopenshot.log: File too small or empty (not uploaded)
Exception / Stacktrace
No stacktrace found in log files
(not much in log files: just installed daily build)
Hey, out of curiousity, is the buffer bar being built for you? See the attached pic.
I have a similar problem. I can add images, but once I add audio, it doesn't buffer and it looks like it's frozen... Preview just doesn't work at all.
I'm wondering if your problem is actually my problem. :D
Hi, I want to add some missing information for this bug: How to reproduce it!
It is NOT sufficient to just add an MKV! I have working MKVs as well (also with longer still images within it).
To get an MKV which definitively breaks the preview of OpenShot you can use OBS Studio:
- Create a scene with a simple screen recording.
- Open the [Settings]. (3. Set the matroska-format for the output.) [see below]
- Important: Do set some smaller canvas resolution to only record the upper left corner of the screen! E.g. input "1024x768" into both the edit fields for "Base (Canvas) Resolution" and "Output (Scaled) Resolution" (to record some classic game which cannot be recorded otherwise or some prepared screencast with this size or ...).
- Close the settings and start the recording.
- It does not matter what you are actually recording, when you stop the process, the resulting file will never work in OpenShot!
It is not necessary to add the file to a track. The file preview will stay black when only adding it to the project files. - Just for completeness:
- When you do add it to a track, the buffer bar is being build up.
- When you export something (like an image sequence), you will also only get black frames.
Also, the black colour is no necessity of this bug! I have screen recordings done this way (of some classic 2D-game) which do show up as dark green - and will produce a dark green export.
Update after some more tests
This bug is NOT depending on the MKV container format! In the above list of steps you can switch back to MP4 as recording container of OBS - and then this MP4 won't be usable in OpenShot! Or you could transcode the recording using ffmpeg - but this will also not fix the incompatibility! E.g., I tested: ffmpeg.exe -i "input.mkv" -preset veryslow -acodec copy "output.mkv" which normally results in smaller files - but still keeps the incompatibility with OpenShot! Or even ffmpeg.exe -i "input.mkv" -vcodec copy -acodec copy "output.mp4" which only changes the container format and keeps all video information as it was - AND still keeps the incompatibility with OpenShot! That means, in the end I got another MP4 of my screen recording (which works fine in every player and editor I know) which does only show up as a black frame in OpenShot! So I guess, the real problem does lie within the video track, and not within the container.
Hello @TigreChat
- If possible, please share your test OBS recording. This will save us time and a consistent file recording settings. This will also make it easier for the lead developer to use and replicate the issues.
- There is a newer release of v3.4.0-release-candidate-14124. Please download this and test again.
I have assigned this to the lead developer so he can review it and provide some feedback and/or the next steps.
- Since nobody did answer, I did record two little OBS samples (in mp4 and matroska containers) and packed and appended them here. When you put them into the last release (3.3.0), you will only see a black preview.
- I am using the portable apps version (https://portableapps.com/apps/music_video/openshot-portable). I do not want to clutter my Windows with unnecessary installer information. So I cannot test daily builds, because there are no portable versions of them.
Thank you @Hubgut for the test files. I extracted both the .mp4 and .mkv files. Imported them both into OpenShot and I am able to preview both of them without any issues.
I am running Windows 11 Pro 24H2 and OpenShot Version: 3.4.0 | 0.5.0 OpenShot-v3.4.0-release-candidate-14193-adff81fe-0b018e34 Release Date: 2025-08-12
That sounds good! But maybe @TigreChat should confirm that my files show the same effect for them like described - since the opening issue already speaks of an OpenShot version of already "3.4.0" (but that was some months ago)? 🤔