Subtitle extraction from streaming media manifests #247

Authored by fstirlitz
Modified from: https://github.com/ytdl-org/youtube-dl/pull/6144

Closes: #73
Fixes:
https://github.com/ytdl-org/youtube-dl/issues/6106
https://github.com/ytdl-org/youtube-dl/issues/14977
https://github.com/ytdl-org/youtube-dl/issues/21438
https://github.com/ytdl-org/youtube-dl/issues/23609
https://github.com/ytdl-org/youtube-dl/issues/28132

Might also fix (untested):
https://github.com/ytdl-org/youtube-dl/issues/15424
https://github.com/ytdl-org/youtube-dl/issues/18267
https://github.com/ytdl-org/youtube-dl/issues/23899
https://github.com/ytdl-org/youtube-dl/issues/24375
https://github.com/ytdl-org/youtube-dl/issues/24595
https://github.com/ytdl-org/youtube-dl/issues/27899

Related:
https://github.com/ytdl-org/youtube-dl/issues/22379
https://github.com/ytdl-org/youtube-dl/pull/24517
https://github.com/ytdl-org/youtube-dl/pull/24886
https://github.com/ytdl-org/youtube-dl/pull/27215

Notes:
* The functions `extractor.common._extract_..._formats` are still kept for compatibility
* Only some extractors have currently been moved to using `_extract_..._formats_and_subtitles`
* Direct subtitle manifests (without a master) are not supported and are wrongly identified as containing video formats
* AES support is untested
* The fragmented TTML subtitles extracted from DASH/ISM are valid, but are unsupported by `ffmpeg` and most video players
    * Their XML fragments can be dumped using `ffmpeg -i in.mp4 -f data -map 0 -c copy out.ttml`.
        Once the unnecessary headers are stripped out of this, it becomes a valid self-contained ttml file
    * The ttml subs downloaded from DASH manifests can also be directly opened with <https://github.com/SubtitleEdit>
* Fragmented WebVTT files extracted from DASH/ISM are also unsupported by most tools
    * Unlike the ttml files, the XML fragments of these cannot be dumped using `ffmpeg`
    * The webtt subs extracted from DASH can be parsed by <https://github.com/gpac/gpac>
    * But validity of the those extracted from ISM are untested

1 files changed, 10 insertions, 4 deletions

diff --git a/yt_dlp/extractor/wat.py b/yt_dlp/extractor/wat.py
index 05dcc1f17..0f1d08da3 100644
--- a/yt_dlp/extractor/wat.py
+++ b/yt_dlp/extractor/wat.py
@@ -69,19 +69,24 @@ class WatIE(InfoExtractor):
         title = video_info['title']
 
         formats = []
+        subtitles = {}
 
         def extract_formats(manifest_urls):
             for f, f_url in manifest_urls.items():
                 if not f_url:
                     continue
                 if f in ('dash', 'mpd'):
-                    formats.extend(self._extract_mpd_formats(
+                    fmts, subs = self._extract_mpd_formats_and_subtitles(
                         f_url.replace('://das-q1.tf1.fr/', '://das-q1-ssl.tf1.fr/'),
-                        video_id, mpd_id='dash', fatal=False))
+                        video_id, mpd_id='dash', fatal=False)
                 elif f == 'hls':
-                    formats.extend(self._extract_m3u8_formats(
+                    fmts, subs = self._extract_m3u8_formats_and_subtitles(
                         f_url, video_id, 'mp4',
-                        'm3u8_native', m3u8_id='hls', fatal=False))
+                        'm3u8_native', m3u8_id='hls', fatal=False)
+                else:
+                    continue
+                formats.extend(fmts)
+                self._merge_subtitles(subs, target=subtitles)
 
         delivery = video_data.get('delivery') or {}
         extract_formats({delivery.get('format'): delivery.get('url')})
@@ -103,4 +108,5 @@ class WatIE(InfoExtractor):
                 video_data, lambda x: x['mediametrie']['chapters'][0]['estatS4'])),
             'duration': int_or_none(video_info.get('duration')),
             'formats': formats,
+            'subtitles': subtitles,
         }