From 3eb9bfbb84dca701f1f09d3b23fc55eb006869b3 Mon Sep 17 00:00:00 2001
From: Aurelien Jacobs <aurel@gnuage.org>
Date: Thu, 4 Sep 2008 23:26:12 +0000
Subject: [PATCH] matroskadec: fix ASS subtitle track packets before emitting
 them Matroska does some butchering when storing the ASS lines. The start and
 end time are removed (because they are duplicated in the container). The
 matroska_fix_ass_packet() function simply restore those start and end time in
 ASS lines to ensure our ASS packets comply with the ASS spec.

Originally committed as revision 15211 to svn://svn.ffmpeg.org/ffmpeg/trunk
---
 libavformat/matroskadec.c | 35 +++++++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)

diff --git a/libavformat/matroskadec.c b/libavformat/matroskadec.c
index 437ac3717e..7452ff0599 100644
--- a/libavformat/matroskadec.c
+++ b/libavformat/matroskadec.c
@@ -28,6 +28,7 @@
  * Specs available on the Matroska project page: http://www.matroska.org/.
  */
 
+#include <stdio.h>
 #include "avformat.h"
 /* For codec_get_id(). */
 #include "riff.h"
@@ -932,6 +933,37 @@ static int matroska_decode_buffer(uint8_t** buf, int* buf_size,
     return -1;
 }
 
+static void matroska_fix_ass_packet(MatroskaDemuxContext *matroska,
+                                    AVPacket *pkt)
+{
+    char *line, *layer, *ptr = pkt->data, *end = ptr+pkt->size;
+    for (; *ptr!=',' && ptr<end-1; ptr++);
+    if (*ptr == ',')
+        layer = ++ptr;
+    for (; *ptr!=',' && ptr<end-1; ptr++);
+    if (*ptr == ',') {
+        int64_t end_pts = pkt->pts + pkt->convergence_duration;
+        int sc = matroska->time_scale * pkt->pts / 10000000;
+        int ec = matroska->time_scale * end_pts  / 10000000;
+        int sh, sm, ss, eh, em, es, len;
+        sh = sc/360000;  sc -= 360000*sh;
+        sm = sc/  6000;  sc -=   6000*sm;
+        ss = sc/   100;  sc -=    100*ss;
+        eh = ec/360000;  ec -= 360000*eh;
+        em = ec/  6000;  ec -=   6000*em;
+        es = ec/   100;  ec -=    100*es;
+        *ptr++ = '\0';
+        len = 50 + end-ptr + FF_INPUT_BUFFER_PADDING_SIZE;
+        if (!(line = av_malloc(len)))
+            return;
+        snprintf(line,len,"Dialogue: %s,%d:%02d:%02d.%02d,%d:%02d:%02d.%02d,%s",
+                 layer, sh, sm, ss, sc, eh, em, es, ec, ptr);
+        av_free(pkt->data);
+        pkt->data = line;
+        pkt->size = strlen(line);
+    }
+}
+
 static void matroska_convert_tags(AVFormatContext *s, EbmlList *list)
 {
     MatroskaTag *tags = list->elem;
@@ -1588,6 +1620,9 @@ static int matroska_parse_block(MatroskaDemuxContext *matroska, uint8_t *data,
                 else
                     pkt->duration = duration;
 
+                if (st->codec->codec_id == CODEC_ID_SSA)
+                    matroska_fix_ass_packet(matroska, pkt);
+
                 dynarray_add(&matroska->packets, &matroska->num_packets, pkt);
             }