avcodec/parser: add fuzzy mode to ff_fetch_timestamp()

This will be needed for the following timestamp fix
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/mpeg12.c

@@ -234,7 +234,7 @@ int ff_mpeg1_find_frame_end(ParseContext *pc, const uint8_t *buf, int buf_size,
                 }
             }
             if (pc->frame_start_found == 0 && s && state == PICTURE_START_CODE) {
-                ff_fetch_timestamp(s, i - 3, 1);
+                ff_fetch_timestamp(s, i - 3, 1, 0);
             }
         }
     }

libavcodec/parser.c

@@ -93,14 +93,16 @@ err_out:
     return NULL;
 }
 
-void ff_fetch_timestamp(AVCodecParserContext *s, int off, int remove)
+void ff_fetch_timestamp(AVCodecParserContext *s, int off, int remove, int fuzzy)
 {
     int i;
 
-    s->dts    =
-    s->pts    = AV_NOPTS_VALUE;
-    s->pos    = -1;
-    s->offset = 0;
+    if (!fuzzy) {
+        s->dts    =
+        s->pts    = AV_NOPTS_VALUE;
+        s->pos    = -1;
+        s->offset = 0;
+    }
     for (i = 0; i < AV_PARSER_PTS_NB; i++) {
         if (s->cur_offset + off >= s->cur_frame_offset[i] &&
             (s->frame_offset < s->cur_frame_offset[i] ||
@@ -108,10 +110,12 @@ void ff_fetch_timestamp(AVCodecParserContext *s, int off, int remove)
             // check disabled since MPEG-TS does not send complete PES packets
             /*s->next_frame_offset + off <*/  s->cur_frame_end[i]){
 
-            s->dts    = s->cur_frame_dts[i];
-            s->pts    = s->cur_frame_pts[i];
-            s->pos    = s->cur_frame_pos[i];
-            s->offset = s->next_frame_offset - s->cur_frame_offset[i];
+            if (!fuzzy || s->cur_frame_dts[i] != AV_NOPTS_VALUE) {
+                s->dts    = s->cur_frame_dts[i];
+                s->pts    = s->cur_frame_pts[i];
+                s->pos    = s->cur_frame_pos[i];
+                s->offset = s->next_frame_offset - s->cur_frame_offset[i];
+            }
             if (remove)
                 s->cur_frame_offset[i] = INT64_MAX;
             if (s->cur_offset + off < s->cur_frame_end[i])
@@ -154,7 +158,7 @@ int av_parser_parse2(AVCodecParserContext *s, AVCodecContext *avctx,
         s->last_pts        = s->pts;
         s->last_dts        = s->dts;
         s->last_pos        = s->pos;
-        ff_fetch_timestamp(s, 0, 0);
+        ff_fetch_timestamp(s, 0, 0, 0);
     }
     /* WARNING: the returned index can be negative */
     index = s->parser->parser_parse(s, avctx, (const uint8_t **) poutbuf,

libavcodec/parser.h

@@ -53,7 +53,8 @@ void ff_parse_close(AVCodecParserContext *s);
  * Fetch timestamps for a specific byte within the current access unit.
  * @param off byte position within the access unit
  * @param remove Found timestamps will be removed if set to 1, kept if set to 0.
+ * @param fuzzy Only use found value if it is more informative than what we already have
  */
-void ff_fetch_timestamp(AVCodecParserContext *s, int off, int remove);
+void ff_fetch_timestamp(AVCodecParserContext *s, int off, int remove, int fuzzy);
 
 #endif /* AVCODEC_PARSER_H */