From be4b4fb8fe5d7f408a247a3344831321301e3607 Mon Sep 17 00:00:00 2001
From: prj-2501 <project_2501@emailuser.net>
Date: Tue, 20 Jun 2023 00:08:34 +0530
Subject: [PATCH] ffmpeg: process all subtitle streams

---
 src/adapters/ffmpeg.rs | 71 +++++++++++++++++++++---------------------
 1 file changed, 35 insertions(+), 36 deletions(-)

diff --git a/src/adapters/ffmpeg.rs b/src/adapters/ffmpeg.rs
index a32e6f9..e83e6b1 100644
--- a/src/adapters/ffmpeg.rs
+++ b/src/adapters/ffmpeg.rs
@@ -54,7 +54,7 @@ struct FFprobeOutput {
 }
 #[derive(Serialize, Deserialize)]
 struct FFprobeStream {
-    codec_type: String, // video,audio,subtitle
+    index: i32,           // stream index
 }
 
 #[async_trait]
@@ -80,17 +80,13 @@ impl WritingFileAdapter for FFmpegAdapter {
         }
         let inp_fname = filepath_hint;
         let spawn_fail = |e| map_exe_error(e, "ffprobe", "Make sure you have ffmpeg installed.");
-        let has_subtitles = {
+        let subtitle_streams = {
             let probe = Command::new("ffprobe")
                 .args(vec![
-                    "-v",
-                    "error",
-                    "-select_streams",
-                    "s",
-                    "-of",
-                    "json",
-                    "-show_entries",
-                    "stream=codec_type",
+                    "-v", "error",                    // show all errors
+                    "-select_streams", "s",           // show only subtitle streams
+                    "-of", "json",                    // use json as output format
+                    "-show_entries", "stream=index",  // show index of subtitle streams
                 ])
                 .arg("-i")
                 .arg(&inp_fname)
@@ -105,7 +101,7 @@ impl WritingFileAdapter for FFmpegAdapter {
                 ));
             }
             let p: FFprobeOutput = serde_json::from_slice(&probe.stdout)?;
-            !p.streams.is_empty()
+            p.streams
         };
         {
             // extract file metadata (especially chapter names in a greppable format)
@@ -138,31 +134,34 @@ impl WritingFileAdapter for FFmpegAdapter {
                 return Err(format_err!("ffprobe failed: {:?}", exit));
             }
         }
-        if has_subtitles {
-            // extract subtitles
-            let mut cmd = Command::new("ffmpeg");
-            cmd.arg("-hide_banner")
-                .arg("-loglevel")
-                .arg("panic")
-                .arg("-i")
-                .arg(&inp_fname)
-                .arg("-f")
-                .arg("webvtt")
-                .arg("-");
-            let mut cmd = cmd.stdout(Stdio::piped()).spawn().map_err(spawn_fail)?;
-            let stdo = cmd.stdout.as_mut().expect("is piped");
-            let time_re = Regex::new(r".*\d.*-->.*\d.*").unwrap();
-            let mut time: String = "".to_owned();
-            // rewrite subtitle times so they are shown as a prefix in every line
-            let mut lines = BufReader::new(stdo).lines();
-            while let Some(line) = lines.next_line().await? {
-                // 09:55.195 --> 09:56.730
-                if time_re.is_match(&line) {
-                    time = line.to_owned();
-                } else if line.is_empty() {
-                    async_writeln!(oup)?;
-                } else {
-                    async_writeln!(oup, "{time}: {line}")?;
+        if subtitle_streams.len() > 0 {
+            for probe_stream in subtitle_streams.iter() {
+                // extract subtitles
+                let mut cmd = Command::new("ffmpeg");
+                cmd.arg("-hide_banner")
+                    .arg("-loglevel").arg("panic")
+                    .arg("-i")
+                    .arg(&inp_fname)
+                    .arg("-map")
+                    .arg(format!("0:{}", probe_stream.index.to_string())) // 0 for first input
+                    .arg("-f")
+                    .arg("webvtt")
+                    .arg("-");
+                let mut cmd = cmd.stdout(Stdio::piped()).spawn().map_err(spawn_fail)?;
+                let stdo = cmd.stdout.as_mut().expect("is piped");
+                let time_re = Regex::new(r".*\d.*-->.*\d.*").unwrap();
+                let mut time: String = "".to_owned();
+                // rewrite subtitle times so they are shown as a prefix in every line
+                let mut lines = BufReader::new(stdo).lines();
+                while let Some(line) = lines.next_line().await? {
+                    // 09:55.195 --> 09:56.730
+                    if time_re.is_match(&line) {
+                        time = line.to_owned();
+                    } else if line.is_empty() {
+                        async_writeln!(oup)?;
+                    } else {
+                        async_writeln!(oup, "{time}: {line}")?;
+                    }
                 }
             }
         }