From 24d54ea7fe1ba128cf8d3521d6738fc73a7c623e Mon Sep 17 00:00:00 2001
From: Carl Hetherington <cth@carlh.net>
Date: Thu, 22 May 2014 16:53:38 +0100
Subject: [PATCH] Basics of noting subtitle times in FFmpegSubtitleStreams.

---
 src/lib/dcpomatic_time.h         |  4 ++++
 src/lib/ffmpeg.cc                | 12 ++++++------
 src/lib/ffmpeg_content.cc        | 15 +++++++++++++++
 src/lib/ffmpeg_content.h         |  3 +++
 src/lib/ffmpeg_decoder.cc        |  8 ++------
 src/lib/ffmpeg_examiner.cc       | 24 +++++++++++++++++++++---
 src/lib/ffmpeg_subtitle_stream.h |  2 ++
 src/lib/subrip_content.cc        |  7 +++++++
 src/lib/subrip_content.h         |  2 ++
 src/lib/subrip_decoder.cc        |  4 +++-
 src/lib/subtitle_content.h       |  6 ++++--
 src/lib/subtitle_decoder.cc      | 10 +++++++---
 src/lib/subtitle_decoder.h       |  4 +++-
 src/lib/util.cc                  | 13 +++++++++++++
 src/lib/util.h                   |  2 ++
 15 files changed, 94 insertions(+), 22 deletions(-)

diff --git a/src/lib/dcpomatic_time.h b/src/lib/dcpomatic_time.h
index e56f58c4b..2a871889a 100644
--- a/src/lib/dcpomatic_time.h
+++ b/src/lib/dcpomatic_time.h
@@ -157,6 +157,10 @@ public:
 
 	ContentTime from;
 	ContentTime to;
+
+	ContentTimePeriod operator+ (ContentTime const & o) const {
+		return ContentTimePeriod (from + o, to + o);
+	}
 };
 
 class DCPTime : public Time
diff --git a/src/lib/ffmpeg.cc b/src/lib/ffmpeg.cc
index ec7ec452e..8505626df 100644
--- a/src/lib/ffmpeg.cc
+++ b/src/lib/ffmpeg.cc
@@ -148,13 +148,13 @@ FFmpeg::setup_decoders ()
 		AVCodecContext* context = _format_context->streams[i]->codec;
 		
 		AVCodec* codec = avcodec_find_decoder (context->codec_id);
-		if (codec == 0) {
-			throw DecodeError (N_("could not find decoder"));
-		}
-		
-		if (avcodec_open2 (context, codec, 0) < 0) {
-			throw DecodeError (N_("could not open decoder"));
+		if (codec) {
+			if (avcodec_open2 (context, codec, 0) < 0) {
+				throw DecodeError (N_("could not open decoder"));
+			}
 		}
+
+		/* We are silently ignoring any failures to find suitable decoders here */
 	}
 }
 
diff --git a/src/lib/ffmpeg_content.cc b/src/lib/ffmpeg_content.cc
index a191959fc..2b507ab37 100644
--- a/src/lib/ffmpeg_content.cc
+++ b/src/lib/ffmpeg_content.cc
@@ -392,3 +392,18 @@ FFmpegContent::audio_analysis_path () const
 	p /= name;
 	return p;
 }
+
+bool
+FFmpegContent::has_subtitle_during (ContentTimePeriod period) const
+{
+	shared_ptr<FFmpegSubtitleStream> stream = subtitle_stream ();
+
+	/* XXX: inefficient */
+	for (vector<ContentTimePeriod>::const_iterator i = stream->periods.begin(); i != stream->periods.end(); ++i) {
+		if (i->from <= period.to && i->to >= period.from) {
+			return true;
+		}
+	}
+
+	return false;
+}
diff --git a/src/lib/ffmpeg_content.h b/src/lib/ffmpeg_content.h
index 6f4980dc7..1a30fb606 100644
--- a/src/lib/ffmpeg_content.h
+++ b/src/lib/ffmpeg_content.h
@@ -73,6 +73,9 @@ public:
 	void set_audio_mapping (AudioMapping);
 	boost::filesystem::path audio_analysis_path () const;
 
+	/* SubtitleContent */
+	bool has_subtitle_during (ContentTimePeriod) const;
+
 	void set_filters (std::vector<Filter const *> const &);
 	
 	std::vector<boost::shared_ptr<FFmpegSubtitleStream> > subtitle_streams () const {
diff --git a/src/lib/ffmpeg_decoder.cc b/src/lib/ffmpeg_decoder.cc
index 7d152e490..d668deb6f 100644
--- a/src/lib/ffmpeg_decoder.cc
+++ b/src/lib/ffmpeg_decoder.cc
@@ -62,6 +62,7 @@ using dcp::Size;
 FFmpegDecoder::FFmpegDecoder (shared_ptr<const FFmpegContent> c, shared_ptr<Log> log)
 	: VideoDecoder (c)
 	, AudioDecoder (c)
+	, SubtitleDecoder (c)
 	, FFmpeg (c)
 	, _log (log)
 	, _subtitle_codec_context (0)
@@ -516,12 +517,7 @@ FFmpegDecoder::decode_subtitle_packet ()
 	/* Subtitle PTS (within the source, not taking into account any of the
 	   source that we may have chopped off for the DCP)
 	*/
-	ContentTime packet_time = ContentTime::from_seconds (static_cast<double> (sub.pts) / AV_TIME_BASE) + _pts_offset;
-
-	ContentTimePeriod period (
-		packet_time + ContentTime::from_seconds (sub.start_display_time / 1e3),
-		packet_time + ContentTime::from_seconds (sub.end_display_time / 1e3)
-		);
+	ContentTimePeriod period = subtitle_period (sub) + _pts_offset;
 
 	AVSubtitleRect const * rect = sub.rects[0];
 
diff --git a/src/lib/ffmpeg_examiner.cc b/src/lib/ffmpeg_examiner.cc
index 013799d03..df12830f8 100644
--- a/src/lib/ffmpeg_examiner.cc
+++ b/src/lib/ffmpeg_examiner.cc
@@ -25,6 +25,7 @@ extern "C" {
 #include "ffmpeg_content.h"
 #include "ffmpeg_audio_stream.h"
 #include "ffmpeg_subtitle_stream.h"
+#include "util.h"
 
 #include "i18n.h"
 
@@ -63,8 +64,15 @@ FFmpegExaminer::FFmpegExaminer (shared_ptr<const FFmpegContent> c)
 		}
 	}
 
-	/* Run through until we find the first audio (for each stream) and video */
-
+	/* Run through until we find:
+	 *   - the first video.
+	 *   - the first audio for each stream.
+	 *   - the subtitle periods for each stream.
+	 *
+	 * We have to note subtitle periods as otherwise we have no way of knowing
+	 * where we should look for subtitles (video and audio are always present,
+	 * so they are ok).
+	 */
 	while (1) {
 		int r = av_read_frame (_format_context, &_packet);
 		if (r < 0) {
@@ -122,7 +130,17 @@ FFmpegExaminer::audio_packet (AVCodecContext* context, shared_ptr<FFmpegAudioStr
 void
 FFmpegExaminer::subtitle_packet (AVCodecContext* context, shared_ptr<FFmpegSubtitleStream> stream)
 {
-
+	int frame_finished;
+	AVSubtitle sub;
+	if (avcodec_decode_subtitle2 (context, &sub, &frame_finished, &_packet) >= 0 && frame_finished) {
+		ContentTimePeriod const period = subtitle_period (sub);
+		if (sub.num_rects == 0 && !stream->periods.empty () && stream->periods.back().to > period.from) {
+			/* Finish the last subtitle */
+			stream->periods.back().to = period.from;
+		} else if (sub.num_rects == 1) {
+			stream->periods.push_back (period);
+		}
+	}
 }
 
 optional<ContentTime>
diff --git a/src/lib/ffmpeg_subtitle_stream.h b/src/lib/ffmpeg_subtitle_stream.h
index 76c71f016..b16b825e7 100644
--- a/src/lib/ffmpeg_subtitle_stream.h
+++ b/src/lib/ffmpeg_subtitle_stream.h
@@ -30,5 +30,7 @@ public:
 	FFmpegSubtitleStream (cxml::ConstNodePtr);
 
 	void as_xml (xmlpp::Node *) const;
+
+	std::vector<ContentTimePeriod> periods;
 };
 
diff --git a/src/lib/subrip_content.cc b/src/lib/subrip_content.cc
index 892578ade..d7825f518 100644
--- a/src/lib/subrip_content.cc
+++ b/src/lib/subrip_content.cc
@@ -109,3 +109,10 @@ SubRipContent::identifier () const
 
 	return s.str ();
 }
+
+bool
+SubRipContent::has_subtitle_during (ContentTimePeriod) const
+{
+	/* XXX */
+	return false;
+}
diff --git a/src/lib/subrip_content.h b/src/lib/subrip_content.h
index 5688f81d5..91de08350 100644
--- a/src/lib/subrip_content.h
+++ b/src/lib/subrip_content.h
@@ -37,6 +37,8 @@ public:
 	DCPTime full_length () const;
 	std::string identifier () const;
 
+	bool has_subtitle_during (ContentTimePeriod) const;
+
 private:
 	DCPTime _length;
 };
diff --git a/src/lib/subrip_decoder.cc b/src/lib/subrip_decoder.cc
index cdc8ccbfe..e832c2d84 100644
--- a/src/lib/subrip_decoder.cc
+++ b/src/lib/subrip_decoder.cc
@@ -19,12 +19,14 @@
 
 #include <dcp/subtitle_string.h>
 #include "subrip_decoder.h"
+#include "subrip_content.h"
 
 using std::list;
 using boost::shared_ptr;
 
 SubRipDecoder::SubRipDecoder (shared_ptr<const SubRipContent> content)
-	: SubRip (content)
+	: SubtitleDecoder (content)
+	, SubRip (content)
 	, _next (0)
 {
 
diff --git a/src/lib/subtitle_content.h b/src/lib/subtitle_content.h
index 92d072ca6..cc91a2df8 100644
--- a/src/lib/subtitle_content.h
+++ b/src/lib/subtitle_content.h
@@ -36,9 +36,11 @@ public:
 	SubtitleContent (boost::shared_ptr<const Film>, boost::filesystem::path);
 	SubtitleContent (boost::shared_ptr<const Film>, cxml::ConstNodePtr, int version);
 	SubtitleContent (boost::shared_ptr<const Film>, std::vector<boost::shared_ptr<Content> >);
-	
+
 	void as_xml (xmlpp::Node *) const;
 
+	virtual bool has_subtitle_during (ContentTimePeriod) const = 0;
+	
 	void set_subtitle_x_offset (double);
 	void set_subtitle_y_offset (double);
 	void set_subtitle_scale (double);
@@ -57,7 +59,7 @@ public:
 		boost::mutex::scoped_lock lm (_mutex);
 		return _subtitle_scale;
 	}
-	
+
 private:
 	friend class ffmpeg_pts_offset_test;
 
diff --git a/src/lib/subtitle_decoder.cc b/src/lib/subtitle_decoder.cc
index d114df979..13cf481c8 100644
--- a/src/lib/subtitle_decoder.cc
+++ b/src/lib/subtitle_decoder.cc
@@ -19,13 +19,15 @@
 
 #include <boost/shared_ptr.hpp>
 #include "subtitle_decoder.h"
+#include "subtitle_content.h"
 
 using std::list;
 using std::cout;
 using boost::shared_ptr;
 using boost::optional;
 
-SubtitleDecoder::SubtitleDecoder ()
+SubtitleDecoder::SubtitleDecoder (shared_ptr<const SubtitleContent> c)
+	: _subtitle_content (c)
 {
 
 }
@@ -49,6 +51,10 @@ template <class T>
 list<shared_ptr<T> >
 SubtitleDecoder::get (list<shared_ptr<T> > const & subs, ContentTimePeriod period)
 {
+	if (!_subtitle_content->has_subtitle_during (period)) {
+		return list<shared_ptr<T> > ();
+	}
+
 	if (subs.empty() || period.from < subs.front()->period().from || period.to > (subs.back()->period().to + ContentTime::from_seconds (10))) {
 		/* Either we have no decoded data, or what we do have is a long way from what we want: seek */
 		seek (period.from, true);
@@ -57,8 +63,6 @@ SubtitleDecoder::get (list<shared_ptr<T> > const & subs, ContentTimePeriod perio
 	/* Now enough pass() calls will either:
 	 *  (a) give us what we want, or
 	 *  (b) hit the end of the decoder.
-	 *
-	 *  XXX: with subs being sparse, this may need more care...
 	 */
 	while (!pass() && (subs.empty() || (subs.front()->period().from > period.from || period.to < subs.back()->period().to))) {}
 
diff --git a/src/lib/subtitle_decoder.h b/src/lib/subtitle_decoder.h
index fea4ab973..164c151e6 100644
--- a/src/lib/subtitle_decoder.h
+++ b/src/lib/subtitle_decoder.h
@@ -33,7 +33,7 @@ class Image;
 class SubtitleDecoder : public virtual Decoder
 {
 public:
-	SubtitleDecoder ();
+	SubtitleDecoder (boost::shared_ptr<const SubtitleContent>);
 
 	std::list<boost::shared_ptr<ContentImageSubtitle> > get_image_subtitles (ContentTimePeriod period);
 	std::list<boost::shared_ptr<ContentTextSubtitle> > get_text_subtitles (ContentTimePeriod period);
@@ -50,6 +50,8 @@ protected:
 private:
 	template <class T>
 	std::list<boost::shared_ptr<T> > get (std::list<boost::shared_ptr<T> > const & subs, ContentTimePeriod period);
+
+	boost::shared_ptr<const SubtitleContent> _subtitle_content;
 };
 
 #endif
diff --git a/src/lib/util.cc b/src/lib/util.cc
index 14dfd1fa5..6e370f577 100644
--- a/src/lib/util.cc
+++ b/src/lib/util.cc
@@ -982,3 +982,16 @@ ScopedTemporary::close ()
 		_open = 0;
 	}
 }
+
+ContentTimePeriod
+subtitle_period (AVSubtitle const & sub)
+{
+	ContentTime const packet_time = ContentTime::from_seconds (static_cast<double> (sub.pts) / AV_TIME_BASE);
+
+	ContentTimePeriod period (
+		packet_time + ContentTime::from_seconds (sub.start_display_time / 1e3),
+		packet_time + ContentTime::from_seconds (sub.end_display_time / 1e3)
+		);
+
+	return period;
+}
diff --git a/src/lib/util.h b/src/lib/util.h
index 58c2771b7..196a6e8f9 100644
--- a/src/lib/util.h
+++ b/src/lib/util.h
@@ -59,6 +59,7 @@ namespace libdcp {
 }
 
 class Job;
+struct AVSubtitle;
 
 extern std::string seconds_to_hms (int);
 extern std::string seconds_to_approximate_hms (int);
@@ -91,6 +92,7 @@ extern int get_optional_int (std::multimap<std::string, std::string> const & kv,
 extern std::string get_optional_string (std::multimap<std::string, std::string> const & kv, std::string k);
 extern void* wrapped_av_malloc (size_t);
 extern int64_t divide_with_round (int64_t a, int64_t b);
+extern ContentTimePeriod subtitle_period (AVSubtitle const &);
 
 /** @class Socket
  *  @brief A class to wrap a boost::asio::ip::tcp::socket with some things
-- 
2.30.2