Bug 792404 - Add nestegg_offset_seek to enable stream switching for DASH-WebM r=kinetik

layout/media/symbols.def.in

@@ -9,6 +9,7 @@ nestegg_destroy
 nestegg_duration
 nestegg_free_packet
 nestegg_init
+nestegg_offset_seek
 nestegg_packet_count
 nestegg_packet_data
 nestegg_packet_track

media/libnestegg/README_MOZILLA

@@ -5,4 +5,4 @@ Makefile.in build files for the Mozilla build system.
 
 The nestegg git repository is: git://github.com/kinetiknz/nestegg.git
 
-The git commit ID used was a4dd140a8c1073d8d5ef7848f83730e12bdfcf18.
+The git commit ID used was ce207d5b7566da2900e728b776a918ff3ab3dbb0.

media/libnestegg/include/nestegg.h

@@ -194,6 +194,15 @@ int nestegg_get_cue_point(nestegg * context, unsigned int cluster_num,
                           int64_t max_offset, int64_t * start_pos,
                           int64_t * end_pos);
 
+/** Seek to @a offset.  Stream will seek directly to offset.
+    Should be used to seek to the start of a resync point, i.e. cluster; the
+    parser will not be able to understand other offsets.
+    @param context Stream context initialized by #nestegg_init.
+    @param offset  Absolute offset in bytes.
+    @retval  0 Success.
+    @retval -1 Error. */
+int nestegg_offset_seek(nestegg * context, uint64_t offset);
+
 /** Seek @a track to @a tstamp.  Stream seek will terminate at the earliest
     key point in the stream at or before @a tstamp.  Other tracks in the
     stream will output packets with unspecified but nearby timestamps.

media/libnestegg/src/nestegg.c

@@ -1647,6 +1647,27 @@ nestegg_get_cue_point(nestegg * ctx, unsigned int cluster_num, int64_t max_offse
   return 0;
 }
 
+int
+nestegg_offset_seek(nestegg * ctx, uint64_t offset)
+{
+  int r;
+
+  /* Seek and set up parser state for segment-level element (Cluster). */
+  r = ne_io_seek(ctx->io, offset, NESTEGG_SEEK_SET);
+  if (r != 0)
+    return -1;
+  ctx->last_id = 0;
+  ctx->last_size = 0;
+
+  while (ctx->ancestor)
+    ne_ctx_pop(ctx);
+
+  ne_ctx_push(ctx, ne_top_level_elements, ctx);
+  ne_ctx_push(ctx, ne_segment_elements, &ctx->segment);
+
+  return 0;
+}
+
 int
 nestegg_track_seek(nestegg * ctx, unsigned int track, uint64_t tstamp)
 {
@@ -1691,17 +1712,7 @@ nestegg_track_seek(nestegg * ctx, unsigned int track, uint64_t tstamp)
   }
 
   /* Seek and set up parser state for segment-level element (Cluster). */
-  r = ne_io_seek(ctx->io, ctx->segment_offset + seek_pos, NESTEGG_SEEK_SET);
+  r = nestegg_offset_seek(ctx, ctx->segment_offset + seek_pos);
-  if (r != 0)
-    return -1;
-  ctx->last_id = 0;
-  ctx->last_size = 0;
-
-  while (ctx->ancestor)
-    ne_ctx_pop(ctx);
-
-  ne_ctx_push(ctx, ne_top_level_elements, ctx);
-  ne_ctx_push(ctx, ne_segment_elements, &ctx->segment);
   ctx->log(ctx, NESTEGG_LOG_DEBUG, "seek: parsing cluster elements");
   r = ne_parse(ctx, NULL, -1);
   if (r != 1)