Ticket #9808: webvtt-unescape.diff

libavcodec/webvttenc.c

@@ -21 +21 @@
  */
 
 #include <stdarg.h>
+#include <strings.h>
 #include "avcodec.h"
 #include "libavutil/avstring.h"
 #include "libavutil/bprint.h"
@@ -28 +29 @@
 #include "ass.h"
 #include "codec_internal.h"
 
+// Unescape what has been escaped in webvtt_event_to_ass
+static const char *webvtt_unescape_ass_chars = "{}";
+
 #define WEBVTT_STACK_SIZE 64
 typedef struct {
     AVCodecContext *avctx;
@@ -155 +159 @@
     .end              = webvtt_end_cb,
 };
 
+static int webvtt_unescape_ass(unsigned char *buf, int buflen)
+{
+    unsigned char *pfrom = buf, *pto = buf;
+    int count = buflen;
+
+    while (count > 0 && *pfrom) {
+        if (*pfrom == '\\' && *(pfrom+1) != '\0' && index(webvtt_unescape_ass_chars, *(pfrom+1)) != NULL) {
+            ++pfrom;
+            --buflen;
+        }
+        *pto = *pfrom;
+        pto++;
+        pfrom++;
+        --count;
+    }
+
+    *pto='\0';
+
+    return buflen;
+}
+
 static int webvtt_encode_frame(AVCodecContext *avctx,
                                unsigned char *buf, int bufsize, const AVSubtitle *sub)
 {
     WebVTTContext *s = avctx->priv_data;
     ASSDialog *dialog;
-    int i;
+    int i, ret;
 
     av_bprint_clear(&s->buffer);
 
@@ -190 +215 @@
         return AVERROR_BUFFER_TOO_SMALL;
     }
     memcpy(buf, s->buffer.str, s->buffer.len);
+    ret = webvtt_unescape_ass(buf, s->buffer.len);
 
-    return s->buffer.len;
+    return ret;
 }
 
 static int webvtt_encode_close(AVCodecContext *avctx)