Fedora 30, kdenlive 18.12.3 installed from rpmfusion. First use of kdenlive. Walked through the tutorial, everything is fine, until I ask for the final step of rendering. Left behind in untitled.mp4.txt:

"Started render process: /usr/bin/melt /tmp/kdenlive_rendering_LUrHqq.mlt in=0 out=852 -profile atsc_1080p_2997 -consumer avformat:/home/karl/Desktop/video-edit/tutorial/untitled.mp4 progress=1 properties=x264-medium f=mp4 vcodec=libx264 acodec=aac g=120 crf=23 ab=160k preset=faster threads=1 real_time=-1
Rendering of /home/karl/Desktop/video-edit/tutorial/untitled.mp4 aborted, resulting video will probably be corrupted."

In the Jobs tab, it whines, while popping a warning dialog:

"Rendering of /home/karl/Desktop/video-edit/tutorial/untitled.mp4 crashed
Unknown flag: 'p'; Usage: freeze [-cdfvVg] [file | +type ...] -c Write output on stdout, don't remove original. -d If given, melting is done instead. -g Use "greedy" parsing (1.5% worse, 40% faster). -f Forces output file to be generated, even if one already exists, and even if no space is saved by freezeing. -i Image mode. -t Text mode. -v Write freezing statistics. -vv means "draw progress indicator". -V Write version and compilation options."

This is the usage summary message of melt. Trying script generation rather than rendering to file, I get this:

#! /bin/sh
RENDERER="/usr/bin/kdenlive_render"
MELT="/usr/bin/melt"
SOURCE_0="file:///home/karl/Desktop/video-edit/tutorial/scripts/francine_001.sh.mlt"
TARGET_0="file:///home/karl/Desktop/video-edit/tutorial/untitled.mp4"
PARAMETERS_0="-pid:18395 in=0 out=852 $MELT atsc_1080p_2997 avformat - $SOURCE_0 $TARGET_0 properties=x264-medium f=mp4 vcodec=libx264 acodec=aac g=120 crf=23 ab=160k preset=faster threads=1 real_time=-1"
$RENDERER $PARAMETERS_0

Invoking the script gives me the same error. Diddling the script to remove (e.g.) -pid argument (as being misunderstood "-p"whatever) simply moves the error somewhere else.

I'm utterly lacking understanding of what's gone wrong. Could someone offer a clue? The obvious realization is that kdenlive doesn't even know how to invoke the render step beneath itself. I find that a remarkable, and remarkably unlikely, error.

Hi, this is a very old kdenlive release.. can you re-try using latest appimage? https://files.kde.org/kdenlive/release/ ... 4.appimage

OK, yes, that worked. Thanx.

That said, running it gives no less than 800 lines of warnings and errors as it starts: 200+ lines of "invalid type" and "invalid context," 150+ lines of "avfilter: XYZ is blacklisted," 30 lines of "uknown asset," 320 lines of format and codec listings, 70 lines of "i18n() needs at least one parameter." Honestly, this doesn't inspire confidence. But yes, it did render.