fade in/out worked out of the box :)

src/render/mod.rs

@@ -278,6 +278,56 @@ impl<'a> Renderer<'a> {
 		});
 		part2 = rectrim.into();
 
+		// fade out the intro
+		let introfade = "introfade";
+		ffmpeg.add_filter(Filter::Fade {
+			input: part1,
+			direction: "out",
+			start: INTRO_LEN - TRANSITION_LEN,
+			duration: TRANSITION_LEN,
+			output: introfade.into()
+		});
+		part1 = introfade.into();
+
+		// fade in the recording
+		let recfadein = "recfadein";
+		ffmpeg.add_filter(Filter::Fade {
+			input: part2,
+			direction: "in",
+			start: Time {
+				seconds: 0,
+				micros: 0
+			},
+			duration: TRANSITION_LEN,
+			output: recfadein.into()
+		});
+		part2 = recfadein.into();
+
+		// fade out the recording
+		let recfadeout = "recfadeout";
+		ffmpeg.add_filter(Filter::Fade {
+			input: part2,
+			direction: "out",
+			start: duration - TRANSITION_LEN,
+			duration: TRANSITION_LEN,
+			output: recfadeout.into()
+		});
+		part2 = recfadeout.into();
+
+		// fade in the outro
+		let outrofade = "outrofade";
+		ffmpeg.add_filter(Filter::Fade {
+			input: part3,
+			direction: "in",
+			start: Time {
+				seconds: 0,
+				micros: 0
+			},
+			duration: TRANSITION_LEN,
+			output: outrofade.into()
+		});
+		part3 = outrofade.into();
+
 		// fast-forward the requested parts in reverse order
 		project.source.fast.sort();
 		for (i, (ff_st, ff_end)) in project.source.fast.iter().rev().enumerate() {
@@ -293,8 +343,6 @@ impl<'a> Renderer<'a> {
 			part2 = recff.into();
 		}
 
-		// TODO fade
-
 		// concatenate everything
 		let concat = "concat";
 		ffmpeg.add_filter(Filter::Concat {