From f7d97f1f2fda9387f7b71d788a4886b50aed8bdc Mon Sep 17 00:00:00 2001
From: uku <hi@uku.moe>
Date: Sun, 18 May 2025 23:03:52 +0200
Subject: [PATCH] feat: add ability to merge audio tracks

---
 src/ffmpeg.rs | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/src/ffmpeg.rs b/src/ffmpeg.rs
index 2ec0192..0c3e036 100644
--- a/src/ffmpeg.rs
+++ b/src/ffmpeg.rs
@@ -105,11 +105,19 @@ pub async fn convert_video(
         Codec::VP9 => &["-c:v", "libvpx-vp9", "-row-mt", "1"],
     };
 
+    // TODO: maybe check if the video has 2 audio tracks? or at least use a "fail-safe" method
+    let merge_args: &[&str] = if merge_tracks {
+        &["-ac", "2", "-filter_complex", "amerge=inputs=2"]
+    } else {
+        &[]
+    };
+
     let mut child = Command::new("ffmpeg")
         .arg("-i")
         .arg(path)
         .args(["-c:a", "libopus", "-b:a", "96k"])
         .args(codec_args)
+        .args(merge_args)
         .args(["-loglevel", "error", "-progress", "-", "-nostats"])
         .arg(&out_path)
         .stdout(Stdio::piped())