It’s trying to use the libva libraries from your system, but they are incompatible with what ffmpeg in the AppImage was built with.
This isn’t code I’ve had a lot to do with, but it appears to be expecting something quite ancient (and on your machine seems to be trying to load a 32-bit version … are you really running a 32-bit OS in 2025?)
I’m seeing:
[AVHWDeviceContext @ 0x7f9d2c004300] libva: /usr/lib/x86_64-linux-gnu/dri/radeonsi_drv_video.so has no function __vaDriverInit_1_0
Because:
$ objdump -T /usr/lib/x86_64-linux-gnu/dri/radeonsi_drv_video.so | grep vaDriver
000000000010fcd0 g DF .text 00000000000003e9 libgallium-25.0.7-2.so __vaDriverInit_1_22
So the appimage is expecting to find VA-API version 1.0, while the drivers on my machine are providing version 1.22 (from libva 2.22.0).
So I assume this is an issue with the deps Craft is configured to use for building the AppImages (and in your case running 64-bit software on a 32-bit OS?).
but libx264 encoder doesn’t apply the bitrate I enter.
Why are you trying to specify or constrain to a bitrate? That’s almost never what you want for offline rendering. You should specify a quality and let the codec decide what to throw how many bits at.
Hard caps on bitrate are pretty much only useful for live streaming through a pipe with strictly constrained bandwidth, which almost nobody has in practice these days on the modern packet-switched internet.