attempt to feed complex filtergraph into graph2dot

src/render/ffmpeg.rs

@@ -1,12 +1,17 @@
-use super::{cmd, filter::Filter};
+use super::{filter::Filter, new_cmd};
 use crate::{
 	render::filter::channel,
 	time::{format_time, Time}
 };
 use anyhow::bail;
-use camino::Utf8PathBuf as PathBuf;
+use camino::{Utf8Path as Path, Utf8PathBuf as PathBuf};
 use rational::Rational;
-use std::{borrow::Cow, fmt::Write as _, process::Command};
+use std::{
+	borrow::Cow,
+	fmt::Write as _,
+	io::Write as _,
+	process::{Command, Stdio}
+};
 
 pub(crate) struct FfmpegInput {
 	pub(crate) concat: bool,
@@ -29,7 +34,7 @@ impl FfmpegInput {
 		}
 	}
 
-	fn append_to_cmd(self, cmd: &mut Command) {
+	fn append_to_cmd(&self, cmd: &mut Command) {
 		if self.concat {
 			cmd.arg("-f").arg("concat").arg("-safe").arg("0");
 		}
@@ -45,7 +50,7 @@ impl FfmpegInput {
 		if let Some(duration) = self.duration {
 			cmd.arg("-t").arg(format_time(duration));
 		}
-		cmd.arg("-i").arg(self.path);
+		cmd.arg("-i").arg(&self.path);
 	}
 }
 
@@ -104,8 +109,8 @@ impl Ffmpeg {
 		self
 	}
 
-	pub fn run(mut self) -> anyhow::Result<()> {
-		let mut cmd = cmd();
+	pub fn run(mut self, filter_graph: Option<&Path>) -> anyhow::Result<()> {
+		let mut cmd = new_cmd();
 		cmd.arg("ffmpeg").arg("-hide_banner").arg("-y");
 
 		// determine whether the video need to be re-encoded
@@ -120,7 +125,7 @@ impl Ffmpeg {
 		}
 
 		// append all the inputs
-		for i in self.inputs {
+		for i in &self.inputs {
 			i.append_to_cmd(&mut cmd);
 		}
 
@@ -149,6 +154,37 @@ impl Ffmpeg {
 				} else {
 					write!(complex, "{}null[v]", channel('v', &self.filters_output));
 				}
+
+				if let Some(filter_graph) = filter_graph {
+					let mut graph2dot = new_cmd();
+					graph2dot.stdin(Stdio::piped());
+					graph2dot.stdout(Stdio::piped());
+					graph2dot.arg("graph2dot");
+					let mut graph2dot = graph2dot.spawn()?;
+
+					let mut dot = new_cmd();
+					dot.stdin(Stdio::from(graph2dot.stdout.take().unwrap()));
+					dot.arg("dot").arg("-Tpng").arg("-o").arg(filter_graph);
+					let mut dot = dot.spawn()?;
+
+					let mut stdin = graph2dot.stdin.take().unwrap();
+					for (i, _) in self.inputs.iter().enumerate() {
+						writeln!(stdin, "nullsrc[{i}];[{i}]nullsink;");
+					}
+					writeln!(stdin, "{complex};")?;
+					writeln!(stdin, "[v]nullsink");
+					drop(stdin);
+
+					let status = graph2dot.wait()?;
+					if !status.success() {
+						bail!("graph2dot failed with status code {:?}", status.code());
+					}
+					let status = dot.wait()?;
+					if !status.success() {
+						bail!("graphviz dot failed with status code {:?}", status.code());
+					}
+				}
+
 				cmd.arg("-filter_complex").arg(complex);
 				cmd.arg("-map").arg("[v]");
 				cmd.arg("-map").arg(channel('a', &self.filters_output));

src/render/mod.rs

@@ -38,7 +38,7 @@ const FF_MULTIPLIER: usize = 8;
 const FF_LOGO_SIZE: usize = 128;
 const LOGO_SIZE: usize = 96;
 
-fn cmd() -> Command {
+fn new_cmd() -> Command {
 	let mut cmd = Command::new("busybox");
 	cmd.arg("ash")
 		.arg("-exuo")
@@ -49,7 +49,7 @@ fn cmd() -> Command {
 }
 
 fn ffprobe() -> Command {
-	let mut cmd = cmd();
+	let mut cmd = new_cmd();
 	cmd.arg("ffprobe")
 		.arg("-v")
 		.arg("error")
@@ -119,11 +119,11 @@ fn svg2mp4(svg: PathBuf, mp4: PathBuf, duration: Time) -> anyhow::Result<()> {
 	});
 	ffmpeg.set_filter_output("out");
 	ffmpeg.set_duration(duration);
-	ffmpeg.run()
+	ffmpeg.run(None)
 }
 
 fn svg2png(svg: &Path, png: &Path, size: usize) -> anyhow::Result<()> {
-	let mut cmd = cmd();
+	let mut cmd = new_cmd();
 	let size = size.to_string();
 	cmd.arg("inkscape")
 		.arg("-w")
@@ -181,7 +181,7 @@ impl<'a> Renderer<'a> {
 			..FfmpegInput::new(recording_txt)
 		});
 		ffmpeg.enable_loudnorm();
-		ffmpeg.run()?;
+		ffmpeg.run(None)?;
 
 		let width = ffprobe_video("stream=width", &recording_mp4)?.parse()?;
 		let height = ffprobe_video("stream=height", &recording_mp4)?.parse()?;
@@ -425,7 +425,7 @@ impl<'a> Renderer<'a> {
 
 		// we're done :)
 		ffmpeg.set_filter_output(overlay);
-		ffmpeg.run()?;
+		ffmpeg.run(Some(&self.target.join("filter_graph.png")))?;
 
 		Ok(output)
 	}