From 96ae67a1d657c0cd4d8d1991742cf5f7dd553d29 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=C3=81lvaro=20Velad=20Galv=C3=A1n?= <ladvan91@hotmail.com>
Date: Mon, 11 Nov 2024 19:06:10 +0100
Subject: [PATCH] feat: Add support for forced subtitles (#208)

---
 streamer/autodetect.py          | 10 ++++++++++
 streamer/input_configuration.py |  8 ++++++++
 streamer/packager_node.py       |  3 +++
 tests/tests.js                  |  3 +++
 4 files changed, 24 insertions(+)

diff --git a/streamer/autodetect.py b/streamer/autodetect.py
index 1cfcb96..0404e04 100644
--- a/streamer/autodetect.py
+++ b/streamer/autodetect.py
@@ -173,3 +173,13 @@ def get_channel_layout(input: Input) -> Optional[AudioChannelLayoutName]:
       return bucket.get_key()
 
   return None
+
+def get_forced_subttitle(input: Input) -> bool:
+  """Returns the forced subtitle value of the input."""
+
+  forced_subttitle_string = _probe(input, 'disposition=forced')
+
+  if forced_subttitle_string is None:
+    return False
+
+  return bool(forced_subttitle_string)
diff --git a/streamer/input_configuration.py b/streamer/input_configuration.py
index 301a351..b34f6b5 100644
--- a/streamer/input_configuration.py
+++ b/streamer/input_configuration.py
@@ -211,6 +211,12 @@ class Input(configuration.Base):
   Not supported with media_type of 'text'.
   """
 
+  forced_subtitle = configuration.Field(bool).cast()
+  """Indicates that the subtitle is forced.
+
+  Only supported with media_type of 'text'.
+  """
+
 
   def __init__(self, *args) -> None:
     super().__init__(*args)
@@ -264,6 +270,8 @@ def disallow_field(name: str, reason: str) -> None:
         reason = 'text streams are not supported in input_type "{}"'.format(
             self.input_type.value)
         disallow_field('input_type', reason)
+      if self.forced_subtitle is None:
+        self.forced_subtitle = autodetect.get_forced_subttitle(self)
 
       # These fields are not supported with text, because we don't process or
       # transcode it.
diff --git a/streamer/packager_node.py b/streamer/packager_node.py
index e80019b..db18b61 100644
--- a/streamer/packager_node.py
+++ b/streamer/packager_node.py
@@ -144,6 +144,9 @@ def _setup_stream(self, stream: OutputStream) -> str:
     if stream.input.drm_label:
       dict['drm_label'] = stream.input.drm_label
 
+    if stream.input.forced_subtitle:
+      dict['forced_subtitle'] = '1'
+
     # Note: Shaka Packager will not accept 'und' as a language, but Shaka
     # Player will fill that in if the language metadata is missing from the
     # manifest/playlist.
diff --git a/tests/tests.js b/tests/tests.js
index b781d7f..0268c16 100644
--- a/tests/tests.js
+++ b/tests/tests.js
@@ -1066,6 +1066,7 @@ function textTracksTests(manifestUrl, format) {
           'name': TEST_DIR + 'Sintel.2010.Arabic.vtt',
           'media_type': 'text',
           'language': 'ar',
+          'forced_subtitle': true,
         },
       ],
     };
@@ -1084,6 +1085,8 @@ function textTracksTests(manifestUrl, format) {
     const languageList = trackList.map(track => track.language);
     languageList.sort();
     expect(languageList).toEqual(['ar', 'en', 'eo', 'es']);
+    const arTrack = trackList.find(track => track.language == 'ar');
+    expect(arTrack.forced).toBeTruthy();
   });
 }