Starting application with I/O redirection via *.desktop file

I start music or video with right click and "open with" in Thunar (Xfce). For every entry, there is a *.desktop file in ~/.local/share/applications or /usr/share/applications. I want to start an application with a pipe and save the output in a file. This works in terminal: mpv file.mp4 > log 2>&1 But that doesn't work when I add the same line to the desktop file: Exec=mpv file.mp4 > log 2>&1 The file is started, but there is no output. How can I do this? Is there something special when using desktop files? also starting with terminal=true, but that didn't work.