For some file types (currently only video files), Airsonic can use an external
program to learn about the file’s contents when it otherwise would be unable to.
The program used for this is ffprobe.
Airsonic will search for an ffprobe binary in your transcode directory and
if it does not exist will search the paths configured in your system via the
PATH environment variable. If you have installed a version of ffmpeg as
recommended for the transcoder, no additional setup should
be required because most distributions of ffmpeg include the ffprobe utility.
You can test whether additional setup is required by trying to run ffprobe
yourself:
$ ffprobe -version
ffprobe version 3.3.4 Copyright (c) 2007-2017 the FFmpeg developers
...
libavutil 55. 58.100 / 55. 58.100
libavcodec 57. 89.100 / 57. 89.100
libavformat 57. 71.100 / 57. 71.100
libavdevice 57. 6.100 / 57. 6.100
libavfilter 6. 82.100 / 6. 82.100
libavresample 3. 5. 0 / 3. 5. 0
libswscale 4. 6.100 / 4. 6.100
libswresample 2. 7.100 / 2. 7.100
libpostproc 54. 5.100 / 54. 5.100
If you don’t get output like that, you should get a copy of ffprobe for your
operating system and place it in Airsonic’s transcode directory.