Subtitle "to" times used to be stored against their "from" times.

Sadly an example shows that from times are not unique.  This patch
uses a hash of stuff from the first AVSubtitle as the key.

1 files changed, 22 insertions, 0 deletions

diff --git a/src/lib/ffmpeg.cc b/src/lib/ffmpeg.cc
index 6103ccd50..df708d923 100644
--- a/src/lib/ffmpeg.cc
+++ b/src/lib/ffmpeg.cc
@@ -26,6 +26,7 @@
 #include "log.h"
 #include "ffmpeg_subtitle_stream.h"
 #include "ffmpeg_audio_stream.h"
+#include "md5_digester.h"
 #include "compose.hpp"
 extern "C" {
 #include <libavcodec/avcodec.h>
@@ -268,6 +269,27 @@ FFmpeg::subtitle_period (AVSubtitle const & sub)
 		);
 }
 
+string
+FFmpeg::subtitle_id (AVSubtitle const & sub)
+{
+	MD5Digester digester;
+	digester.add (sub.start_display_time);
+	digester.add (sub.end_display_time);
+	digester.add (sub.pts);
+	for (unsigned int i = 0; i < sub.num_rects; ++i) {
+		AVSubtitleRect* rect = sub.rects[i];
+		digester.add (rect->x);
+		digester.add (rect->y);
+		digester.add (rect->w);
+		digester.add (rect->h);
+		int const line = rect->pict.linesize[0];
+		for (int j = 0; j < rect->h; ++j) {
+			digester.add (rect->pict.data[0] + j * line, line);
+		}
+	}
+	return digester.get ();
+}
+
 /** Compute the pts offset to use given a set of audio streams and some video details.
  *  Sometimes these parameters will have just been determined by an Examiner, sometimes
  *  they will have been retrieved from a piece of Content, hence the need for this method