From 5c50b3325151f027a7ece4553985e5b2654eed05 Mon Sep 17 00:00:00 2001
From: Dominic <git@msrd0.de>
Date: Sat, 6 Jan 2024 18:55:27 +0100
Subject: [PATCH] allow preprocessing to keep stereo; asks which files to use

---
 src/main.rs          | 33 ++++++++++++++++++++++++++++++---
 src/render/ffmpeg.rs | 23 ++++++++++++++++-------
 src/render/mod.rs    |  2 +-
 3 files changed, 47 insertions(+), 11 deletions(-)

diff --git a/src/main.rs b/src/main.rs
index a6715b6..52e8565 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -37,12 +37,17 @@ struct Args {
 	course: String,
 
 	/// The memory limit for external tools like ffmpeg.
-	#[clap(short, long, default_value = "8G")]
+	#[clap(short, long, default_value = "12G")]
 	mem_limit: String,
 
 	/// Transcode the final video clip down to the minimum resolution specified.
 	#[clap(short, long)]
-	transcode: Option<Resolution>
+	transcode: Option<Resolution>,
+
+	/// Treat the audio as stereo. By default, only one channel from the input stereo will
+	/// be used, assuming either the other channel is backup or the same as the used.
+	#[clap(short, long, default_value = "false")]
+	stereo: bool
 }
 
 macro_rules! resolutions {
@@ -133,6 +138,7 @@ struct ProjectLecture {
 #[derive(Deserialize, Serialize)]
 struct ProjectSource {
 	files: Vec<String>,
+	stereo: bool,
 
 	#[serde_as(as = "Option<DisplayFromStr>")]
 	start: Option<Time>,
@@ -171,6 +177,18 @@ struct ProjectProgress {
 	transcoded: BTreeSet<Resolution>
 }
 
+fn ask(question: impl Display) -> String {
+	let mut stdout = io::stdout().lock();
+	let mut stdin = io::stdin().lock();
+
+	writeln!(stdout, "{question}").unwrap();
+	let mut line = String::new();
+	write!(stdout, "> ").unwrap();
+	stdout.flush().unwrap();
+	stdin.read_line(&mut line).unwrap();
+	line.trim().to_owned()
+}
+
 fn ask_time(question: impl Display) -> Time {
 	let mut stdout = io::stdout().lock();
 	let mut stdin = io::stdin().lock();
@@ -212,7 +230,9 @@ fn main() {
 			let entry = entry.unwrap();
 			let name = entry.file_name();
 			let lower = name.to_ascii_lowercase();
-			if (lower.ends_with(".mp4") || lower.ends_with(".mts"))
+			if (lower.ends_with(".mp4")
+				|| lower.ends_with(".mts")
+				|| lower.ends_with(".mkv"))
 				&& entry.file_type().unwrap().is_file()
 			{
 				files.push(String::from(name));
@@ -220,12 +240,19 @@ fn main() {
 		}
 		files.sort_unstable();
 		assert!(!files.is_empty());
+
 		println!("I found the following source files: {files:?}");
+		files = ask("Which source files would you like to use? (specify multiple files separated by whitespace)")
+			.split_ascii_whitespace()
+			.map(String::from)
+			.collect();
+		assert!(!files.is_empty());
 
 		let project = Project {
 			lecture: ProjectLecture { course, date },
 			source: ProjectSource {
 				files,
+				stereo: args.stereo,
 				start: None,
 				end: None,
 				fast: Vec::new(),
diff --git a/src/render/ffmpeg.rs b/src/render/ffmpeg.rs
index 543ad7d..00597ca 100644
--- a/src/render/ffmpeg.rs
+++ b/src/render/ffmpeg.rs
@@ -157,7 +157,9 @@ enum FfmpegFilter {
 		filters: Vec<Filter>,
 		output: Cow<'static, str>
 	},
-	Loudnorm,
+	Loudnorm {
+		stereo: bool
+	},
 	Rescale(Resolution)
 }
 
@@ -216,10 +218,14 @@ impl Ffmpeg {
 		self
 	}
 
-	pub fn enable_loudnorm(&mut self) -> &mut Self {
+	pub fn enable_loudnorm(&mut self, loudnorm_stereo: bool) -> &mut Self {
 		match &mut self.filter {
-			FfmpegFilter::None => self.filter = FfmpegFilter::Loudnorm,
-			FfmpegFilter::Loudnorm => {},
+			FfmpegFilter::None => {
+				self.filter = FfmpegFilter::Loudnorm {
+					stereo: loudnorm_stereo
+				}
+			},
+			FfmpegFilter::Loudnorm { stereo } if *stereo == loudnorm_stereo => {},
 			_ => panic!("An incompatible type of filter has been set before")
 		}
 		self
@@ -228,7 +234,6 @@ impl Ffmpeg {
 	pub fn rescale_video(&mut self, res: Resolution) -> &mut Self {
 		match &mut self.filter {
 			FfmpegFilter::None => self.filter = FfmpegFilter::Rescale(res),
-			FfmpegFilter::Loudnorm => {},
 			_ => panic!("An incompatible type of filter has been set before")
 		}
 		self
@@ -243,7 +248,7 @@ impl Ffmpeg {
 		let (vdec, venc, aenc) = match &self.filter {
 			FfmpegFilter::None => (false, false, false),
 			FfmpegFilter::Filters { .. } => (false, true, true),
-			FfmpegFilter::Loudnorm => (false, false, true),
+			FfmpegFilter::Loudnorm { .. } => (false, false, true),
 			FfmpegFilter::Rescale(_) => (true, true, false)
 		};
 
@@ -286,7 +291,7 @@ impl Ffmpeg {
 				cmd.arg("-map").arg("[v]");
 				cmd.arg("-map").arg(channel('a', &output));
 			},
-			FfmpegFilter::Loudnorm => {
+			FfmpegFilter::Loudnorm { stereo: false } => {
 				cmd.arg("-af").arg(concat!(
 					"pan=mono|c0=FR,",
 					"loudnorm=dual_mono=true:print_format=summary,",
@@ -294,6 +299,10 @@ impl Ffmpeg {
 					"aformat=sample_rates=48000"
 				));
 			},
+			FfmpegFilter::Loudnorm { stereo: true } => {
+				cmd.arg("-af")
+					.arg("loudnorm=print_format=summary,aformat=sample_rates=48000");
+			},
 			FfmpegFilter::Rescale(res) => {
 				cmd.arg("-vf").arg(if vaapi {
 					format!("scale_vaapi=w={}:h={}", res.width(), res.height())
diff --git a/src/render/mod.rs b/src/render/mod.rs
index e2576e2..9bb4c39 100644
--- a/src/render/mod.rs
+++ b/src/render/mod.rs
@@ -211,7 +211,7 @@ impl<'a> Renderer<'a> {
 			concat: true,
 			..FfmpegInput::new(recording_txt)
 		});
-		ffmpeg.enable_loudnorm();
+		ffmpeg.enable_loudnorm(project.source.stereo);
 		ffmpeg.run()?;
 
 		let width = ffprobe_video("stream=width", &recording_mkv)?.parse()?;