1.2.0: add subtitle delay option (--subtitle-delay <seconds>)

.gitignore

@@ -8,3 +8,4 @@ build
 *.mkv
 *.jpg
 *.png
+.vscode

makefile

@@ -26,7 +26,7 @@ NUMFILES        := $$(($(words $(CXXSRC))))
 DEFINES         := -D__USE_MINGW_ANSI_STDIO=1
 SANITISE        :=
 
-CXXFLAGS        += -std=c++17 -fvisibility=hidden -O3 -c -Wall -fno-omit-frame-pointer $(SANITISE) $(DEFINES)
+CXXFLAGS        += -std=c++17 -fvisibility=hidden -O0 -g -c -Wall -fno-omit-frame-pointer $(SANITISE) $(DEFINES)
 LDFLAGS         += $(SANITISE) -fvisibility=hidden
 
 PRECOMP_HDRS    := source/include/precompile.h

source/arguments.cpp

@@ -28,6 +28,7 @@
 #define ARG_STOP_ON_ERROR                   "--stop-on-error"
 #define ARG_SUBTITLE_LANGS                  "--subtitle-langs"
 #define ARG_SKIP_NCOP_NCED                  "--skip-ncop-nced"
+#define ARG_SUBTITLE_DELAY                  "--subtitle-delay"
 #define ARG_PREFER_SDH_SUBS                 "--prefer-sdh-subs"
 #define ARG_PREFER_TEXT_SUBS                "--prefer-text-subs"
 #define ARG_PREFER_ENGLISH_TITLE            "--prefer-eng-title"
@@ -58,6 +59,10 @@ static void setupMap()
 		"enable metadata tagging"
 	});
 
+	helpList.push_back({ ARG_SUBTITLE_DELAY,
+		"number of seconds (eg. +0.1, -1.7) to delay the subtitles by (applies to both embedded subtitles and the extra-subs input)"
+	});
+
 	helpList.push_back({ ARG_MANUAL_SERIES_TITLE,
 		"override the series title with the given string"
 	});
@@ -568,6 +573,31 @@ namespace args
 						exit(-1);
 					}
 				}
+				else if(!strcmp(argv[i], ARG_SUBTITLE_DELAY))
+				{
+					if(i != argc - 1)
+					{
+						i++;
+						char* end = nullptr;
+						auto delay = strtod(argv[i], &end);
+
+						if(end != argv[i] + strlen(argv[i]))
+						{
+							util::error("%serror:%s invalid number '%s' for subtitle delay", COLOUR_RED_BOLD, COLOUR_RESET,
+								argv[i]);
+							exit(-1);
+						}
+
+						config::setSubtitleDelay(delay);
+						continue;
+					}
+					else
+					{
+						util::error("%serror:%s expected decimal number after '%s' option", COLOUR_RED_BOLD, COLOUR_RESET,
+							argv[i]);
+						exit(-1);
+					}
+				}
 				else if(!strcmp(argv[i], ARG_OUTPUT_FOLDER))
 				{
 					if(i != argc - 1)

source/config.cpp

@@ -271,6 +271,8 @@ namespace config
 	static int manualSeasonNumber = -1;
 	static int manualEpisodeNumber = -1;
 
+	static double subtitleDelay = 0;
+
 
 	void setAudioLangs(const std::vector<std::string>& xs)      { audioLangs = xs; }
 	void setSubtitleLangs(const std::vector<std::string>& xs)   { subtitleLangs = xs; }
@@ -309,6 +311,7 @@ namespace config
 	bool shouldSkipNCOPNCED()               { return skipNCOPNCED; }
 	int getSeasonNumber()                   { return manualSeasonNumber; }
 	int getEpisodeNumber()                  { return manualEpisodeNumber; }
+	double getSubtitleDelay()               { return subtitleDelay; }
 
 	void setManualMovieId(const std::string& x)     { movieId = x; }
 	void setManualSeriesId(const std::string& x)    { seriesId = x; }
@@ -340,6 +343,7 @@ namespace config
 	void setSkipNCOPNCED(bool x)                    { skipNCOPNCED = x; }
 	void setSeasonNumber(int x)                     { manualSeasonNumber = x; }
 	void setEpisodeNumber(int x)                    { manualEpisodeNumber = x; }
+	void setSubtitleDelay(double x)                 { subtitleDelay = x; }
 
 	void setConfigPath(const std::string& x)
 	{

source/include/defs.h

@@ -232,11 +232,15 @@ namespace config
 	int getSeasonNumber();
 	int getEpisodeNumber();
 
+	double getSubtitleDelay();
 
 	bool isMuxing();
 	bool isTagging();
 
 
+
+	void setSubtitleDelay(double seconds);
+
 	void setAudioLangs(const std::vector<std::string>& xs);
 	void setSubtitleLangs(const std::vector<std::string>& xs);
 

source/muxing/driver.cpp

@@ -54,7 +54,7 @@ namespace mux
 
 	// refer: https://github.com/FFmpeg/FFmpeg/blob/10bcc41bb40ba479bfc5ad29b1650a6b335437a8/doc/examples/remuxing.c
 	static bool writeOutput(const std::fs::path& outfile, AVFormatContext* inctx, AVFormatContext* ssctx,
-		const std::vector<AVStream*>& finalStreams, std::unordered_map<AVStream*, size_t>& finalStreamMap)
+		const std::vector<AVStream*>& finalStreams, std::unordered_map<AVStream*, size_t>& finalStreamMap, double subtitleDelay)
 	{
 		AVFormatContext* outctx = 0;
 		if(avformat_alloc_output_context2(&outctx, nullptr, "matroska", outfile.string().c_str()) < 0)
@@ -105,7 +105,7 @@ namespace mux
 		int64_t maxPts = 0;
 		size_t frameCount = 0;
 
-		auto copy_frames = [&maxPts, &frameCount, &finalStreamMap](AVFormatContext* inctx, AVFormatContext* ssctx,
+		auto copy_frames = [&maxPts, &frameCount, &finalStreamMap, subtitleDelay](AVFormatContext* inctx, AVFormatContext* ssctx,
 			AVFormatContext* outctx)
 		{
 			// is this even advisable??? subtitle files should be small, right??
@@ -148,7 +148,7 @@ namespace mux
 				return a->dts < b->dts;
 			});
 
-			auto copy_packet = [&frameCount, &maxPts, &finalStreamMap](AVFormatContext* outctx, AVStream* istrm, AVPacket* pkt) {
+			auto copy_packet = [&frameCount, &maxPts, &finalStreamMap, subtitleDelay](AVFormatContext* outctx, AVStream* istrm, AVPacket* pkt) {
 
 				// looks like we're re-using the same packet.
 				pkt->stream_index = finalStreamMap[istrm];
@@ -166,6 +166,15 @@ namespace mux
 				pkt->duration = av_rescale_q(pkt->duration, istrm->time_base, ostrm->time_base);
 				pkt->pos = -1;
 
+				// check for subtitles
+				if(istrm->codecpar->codec_type == AVMEDIA_TYPE_SUBTITLE)
+				{
+					// this is the subtitle delay.
+					auto delay = subtitleDelay;
+					auto pts_delay = (delay * ostrm->time_base.den) / ostrm->time_base.num;
+					pkt->pts += pts_delay;
+				}
+
 				if(pkt->dts == AV_NOPTS_VALUE)
 				{
 					util::error("frame %d (s:%d) has no dts", frameCount, pkt->stream_index);
@@ -867,10 +876,13 @@ namespace mux
 
 
 
+		if(auto d = config::getSubtitleDelay(); d != 0)
+			util::log("subtitle delay: %.3f s", d);
+
 		// make the output file:
 		if(!config::isDryRun())
 		{
-			if(!writeOutput(outfile, ctx, ssctx, finalStreams, finalStreamMap))
+			if(!writeOutput(outfile, ctx, ssctx, finalStreams, finalStreamMap, config::getSubtitleDelay()))
 				return false;
 		}