take audio from left instead of right channel

src/render/ffmpeg.rs

@@ -335,7 +335,7 @@ impl Ffmpeg {
 			},
 			FfmpegFilter::Loudnorm { stereo: false } => {
 				cmd.arg("-af").arg(concat!(
-					"pan=mono|c0=FR,",
+					"pan=mono|c0=FL,",
 					"loudnorm=dual_mono=true:print_format=summary,",
 					"pan=stereo|c0=c0|c1=c0,",
 					"aformat=sample_rates=48000"