ffmpeg: enable NDR client to play

Set audio driver if forgotten:

set SDL_AUDIODRIVER=directsound

Examples:

"H:\_Conrad lokal\Downloads\FFmpeg\bin\ffplay.exe" -f lavfi -i "amovie=Mucke.wav ,ebur128=video=1:meter=9:gauge=s:scale=relative:target=-13:size=640x480 [out0][out1]"

"H:\_Conrad lokal\Downloads\FFmpeg\bin\ffplay.exe" -f lavfi -i "amovie=T:\Maus\VPN\AUDIO~4T~\zelckc\Mucke.wav,ebur128=video=1:meter=9:gauge=s:scale=relative:target=-13:size=640x480 [out0][out1]"