<font face="Arial, Verdana">Nope, trying to use avconv on the remote server doesn't appear to work either. It looks like the remote server is trying to call avconv with the same parameters as ffmpeg, but on the printer's server (RPi), it uses distinct arguments for avconv. I'm using avconv on the RPi because apparently Debian doesn't like ffmpeg, so it's not in their repository. The remote server is Gentoo, and it has both ffmpeg and avconv available. The videos will render just fine on the RPi, but I don't want them to render there because long rendering jobs can cause buffering problems while printing that lead to my printer pausing while waiting for additional instrucutions; I've lost a few prints due to excess filament build up and burning in these cases.</font>

<font face="Arial, Verdana">Works on RPi: 2017-05-04 23:27:16: /usr/bin/avconv -loglevel error -r 10 -i /var/lib/Repetier-Server/printer/Anet_A2_Plus/timelapse/20170503T231410_Platform_Jack_100fill/image_%08d.jpg -i /usr/local/Repetier-Server/www/img/watermark.png -c:v libx264 -filter_complex [0:v][1:v] overlay=x=10:y=10 -threads 1 -r 10 -pix_fmt yuv420p -profile:v baseline -movflags faststart -b:v 1000k -y /var/lib/Repetier-Server/printer/Anet_A2_Plus/timelapse/20170503T231410_Platform_Jack_100fill/video.mp4</font>

Doesn't work on Linux PC: 2017-05-04 23:34:41: /usr/bin/avconv -loglevel error -f concat -i /var/lib/Repetier-Server/tmp/dcd1d482-1183-4bcf-ad49-99c3dede04dc/input.txt -i /var/lib/Repetier-Server/tmp/dcd1d482-1183-4bcf-ad49-99c3dede04dc/watermark.png -c:v libx264 -filter_complex [0:v][1:v] overlay=10:10 -threads 4 -r 10 -pix_fmt yuv420p -profile:v baseline -level 3.0 -movflags +faststart -b:v 1000k -y /var/lib/Repetier-Server/tmp/dcd1d482-1183-4bcf-ad49-99c3dede04dc/video.mp4

Error:

"conversionError" : "Unknown input format: 'concat'",

"conversionMode" : 3,