Subtitles: [filter avfilter.subtitles] Unexpected return format

Help
1

I’ve been using the Speech Recognition feature to add subtitles to my storytime videos until the latest update. Now, whenever I use it, the subtitles appear on the timeline, but not in the preview or the rendered video. I’ve searched for workarounds, but there’s nothing I can find with the best of my Google-fu.

Kdenlive version: 25.08.2 [Searched for higher versions, came up blank]

OS deets:

CachyOS Linux
KDE Plasma V 6.4.55
KDE Frameworks V 6.19.0 [QT version same number]
Kernel V 6.17.4-4-cACHYOS (64-bit)
Graphics platform: X11

If y’all need my hardware, I’ll attempt to edit it into this post.

Strictly IMHO, it looks like the filters need a good kicking, as there’s another person with a similar error message on the forum. We are doing different things, I checked.

Thanks so much for your time and patience with me.

2

Can you reproduce this using the AppImage? If so, is the subtitle track set to be visible? (see the icons to the left of it on the timeline).

3

I can’t figure out how to get AppImage running but have the same issue on CachyOS

After the update it gives the same [filter avfilter.subtitles] Unexpected return format error even if you create new empty subtitle layer

4

After you made the .appimage file executable and run it the first time what are the error messages?

5

I have no idea what AppImage even is. TIL it exists. How do use?

6

Download from here, make it executable, run it from the terminal.

7

I’ve been having the same issue with version 25.08.2 but on Arch.
It doesn’t matter if I use the speech recognition or just add the subtitles there myself. The point is - any subtitles produce this bug.
I also tried downgrading but then I can’t even run KdenLive. So I’m stuck on this version until it gets fixed.

I also tried running it from the terminal as you suggested and this is what I’m getting

[swscaler @ 0x7f6492838680] Unsupported input (Operation not supported): fmt:yuyv422 csp:bt709 prim:reserved trc:reserved → fmt:yuv422p csp:unknown prim:reserved trc:reserved
MLT: “[filter avfilter.subtitles ] Cannot get frame from buffer sink”
MLT: “[filter avfilter.subtitles ] Unexpected return format”
8

This issue also happens whenever I try to render the entire project to a file. The rendering job crashes. With the error log being just the following message on repeat. Which is the same message as from my previous comment.

[swscaler @ 0x7fdc341d3340] Unsupported input (Operation not supported): fmt:yuyv422 csp:bt709 prim:reserved trc:reserved → fmt:yuv422p csp:unknown prim:reserved trc:reserved [filter avfilter.subtitles] Cannot get frame from buffer sink [filter avfilter.subtitles] Unexpected return format

9

Be warned, I am about to bombard with a metric heckton of screencaps [One post at a time because forum rules].

First, the messages when I start from the konsole prompt:

Screenshot_20251026_192742
Screenshot_20251026_1927421115×1343 195 KB

By Saint Isadorus, this had better work, I have tried FOUR firkin times to share this GD info!

10

Page 2:

KdenliveStart2
KdenliveStart21121×1314 154 KB

11

Then the absolute FLOOD of messages I got when I tried to load the video file I wanted to subtitle. Part 1:

KdenliveError1
KdenliveError11117×1339 349 KB

12

I had immense difficulty getting an accurate page 2 with those because the messages were incredibly hard to tell apart as I scrolled down. I did my best to capture the different ones for part 2:

KdenliveError2
KdenliveError21117×1339 158 KB

13

At least part 3 was easier:

KdenliveError3
KdenliveError31117×681 157 KB

I sure hope y’all can interpret them because it is almost pure gibberish to my 53YO ass.

14

Not only that, it’s completely useless to us.

So I repeat:

Can you reproduce this using the AppImage?

Because if you can’t, then we can’t help you, it’s a problem only your distro maintainers can fix for you. Coredumping mountains of other junk doesn’t change that.

15

Misunderstood the assignment. But yes, I started from Konsole and got the exact same error as always. IDK about installing anew from Konsole because it took a family expert to install it last time.

16

I’ve installed and successfully launched the AppImage by using Gear Lever, subtitles work without errors.

Thank you

17

Thanks - that would confirm that (once again) there are distros shipping untested/busted packages. Sticking to the AppImages should give you the least problems (and things that we can address here). We can’t fix busted distro packages.

2 Likes
18

As a KDE contributor and KDE package maintainer for openSUSE I find the attitude unproductive at best. I’m much willing to try and fix this issue as well, if it’s something in the dependencies.

At least knowing where to look would be helpful.

19

I’m not sure which part of the simple fact that we can’t fix things we don’t maintain you consider to be “attitude” - but hey, glad you’ve joined the forum today.

I look forward to you testing and fixing the packages you maintain, and liasing with all of the other distro maintainers who still aren’t paying any attention to what is reported here, or testing the packages they publish themselves.

If you search the forum for variations of “have you tested it with the AppImage” and “that fixed it for me thanks!” you should pretty quickly come up to speed on the scale and shape of the problem and which distros tend to be overrepresented in those threads.

20

The bug report, which you should have linked, has a very helpful response by one of the KDEnlive team (completely different than what shown here), which points out to a bug in MLT with ffmpeg 8, with a patch that unfortunately hasn’t made yet to a stable MLT release (and yes, I did try to backport the patch, unsuccessfully so far). And that’s why the job of an integrator, like a distro maintainer, is important (there’s a distributions mailing list where larger projects like Frameworks or Plasma communicate such breakages).

I found this forum post because I had the same issue: this forum post was unhelpful, while the bug report (https://bugs.kde.org/show_bug.cgi?id=510274) provided what was needed.

(FTR, don’t judge a book by its cover: I’ve been involved in KDE as a drive-by contributor far more than my participation here)