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written by Ivan Alenko
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posted in category Creativity / Kdenlive
posted at 10. Oct '21

Debugging Render Problems With Kdenlive

As a hobby video editor I love Kdenlive, easy to use, total control over render settings.

But yesterday, it was the second time in months, I bumped into an issue a video render wasnn’t contained the video part, only the audio. And I used a default video render profile. And then I got to render the video, but the audio wasn’t included. 4k libvpx encoder can’t handle video with 59.999 fps coming from nVidia recording software with 60fps rendering profile (30 fps works for some reason, don’t know why yet).

The frustrating part is everything seems ok, Kdenlive doesn’t communicate issues coming from Melt (MLT) which does the rendering part. To see errors:

  • click “Render” and choose the profile
  • click “Generate Script” and save the file
  • fire up the console
  • melt-7 myproject.mlt or melt myproject.mlt

Then you’ll see stuff like:

damon@rapthalia:~/Videos/kdenlive-renderqueue> melt-7 myproject.mlt 
No LADSPA plugins were found!

Check your LADSPA_PATH environment variable.
+-----+ +-----+ +-----+ +-----+ +-----+ +-----+ +-----+ +-----+ +-----+
|1=-10| |2= -5| |3= -2| |4= -1| |5=  0| |6=  1| |7=  2| |8=  5| |9= 10|
+-----+ +-----+ +-----+ +-----+ +-----+ +-----+ +-----+ +-----+ +-----+
+---------------------------------------------------------------------+
|               H = back 1 minute,  L = forward 1 minute              |
|                 h = previous frame,  l = next frame                 |
|           g = start of clip, j = next clip, k = previous clip       |
|                0 = restart, q = quit, space = play                  |
+---------------------------------------------------------------------+
[libopus @ 0x7f2ee0005980] Value 0.000000 for parameter 'frame_duration' out of range [2.5 - 120]
[libaom-av1 @ 0x7f2ee0001d00] Failed to initialize encoder: Invalid parameter
[libaom-av1 @ 0x7f2ee0001d00]   Additional information: g_timebase.den out of range [1..1000000000]
[libopus @ 0x7f2ee0003d00] Value 0.000000 for parameter 'frame_duration' out of range [2.5 - 120]
[webm @ 0x7f2ee0000f40] Using AVStream.codec to pass codec parameters to muxers is deprecated, use AVStream.codecpar instead.
[webm @ 0x7f2ee0000f40] Using AVStream.codec to pass codec parameters to muxers is deprecated, use AVStream.codecpar instead.
[webm @ 0x7f2ee0000f40] Timestamps are unset in a packet for stream 1. This is deprecated and will stop working in the future. Fix your code to set the timestamps properly
[webm @ 0x7f2ee0000f40] Encoder did not produce proper pts, making some up.
Current Position:       1961


libopus and webm messages are not critical here, but libaom-av1 is. The process will create a file, but the video won’t be there. Frankly I think it should just fail.

Version:

i+ | kdenlive      | package | 21.08.1-1.2 | x86_64 | openSUSE-Tumbleweed-Oss
i | melt                     | package | 7.0.1-4.2 | x86_64 | openSUSE-Tumbleweed-Oss

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