dashdemux: Fix snap SIDX seeking and report if we're going outside the index

Instead of just going to the first or last fragment, report if we're
going outside the index. This should never happen unless there's a bug
or the stream is broken.

Allow some possibility for inaccuracies here though.

1 files changed, 59 insertions, 54 deletions

diff --git a/ext/dash/gstdashdemux.c b/ext/dash/gstdashdemux.c
index d28a3e259..06152a702 100644
--- a/ext/dash/gstdashdemux.c
+++ b/ext/dash/gstdashdemux.c
@@ -1247,7 +1247,7 @@ gst_dash_demux_index_entry_search (GstSidxBoxEntry * entry, GstClockTime * ts,
     return 0;
 }
 
-static void
+static GstFlowReturn
 gst_dash_demux_stream_sidx_seek (GstDashDemuxStream * dashstream,
     gboolean forward, GstSeekFlags flags, GstClockTime ts,
     GstClockTime * final_ts)
@@ -1255,56 +1255,64 @@ gst_dash_demux_stream_sidx_seek (GstDashDemuxStream * dashstream,
   GstSidxBox *sidx = SIDX (dashstream);
   GstSidxBoxEntry *entry;
   gint idx = sidx->entries_count;
+  GstFlowReturn ret = GST_FLOW_OK;
 
-  /* check whether ts is already past the last element or not */
-  if (sidx->entries[idx - 1].pts + sidx->entries[idx - 1].duration >= ts) {
-    GstSearchMode mode = GST_SEARCH_MODE_BEFORE;
+  if (sidx->entries_count == 0)
+    return GST_FLOW_EOS;
 
-    if ((flags & GST_SEEK_FLAG_SNAP_NEAREST) == GST_SEEK_FLAG_SNAP_NEAREST) {
-      mode = GST_SEARCH_MODE_BEFORE;
-    } else if ((forward && (flags & GST_SEEK_FLAG_SNAP_AFTER)) ||
-        (!forward && (flags & GST_SEEK_FLAG_SNAP_BEFORE))) {
-      mode = GST_SEARCH_MODE_AFTER;
-    } else {
-      mode = GST_SEARCH_MODE_BEFORE;
-    }
+  entry =
+      gst_util_array_binary_search (sidx->entries, sidx->entries_count,
+      sizeof (GstSidxBoxEntry),
+      (GCompareDataFunc) gst_dash_demux_index_entry_search,
+      GST_SEARCH_MODE_EXACT, &ts, NULL);
 
-    entry =
-        gst_util_array_binary_search (sidx->entries, sidx->entries_count,
-        sizeof (GstSidxBoxEntry),
-        (GCompareDataFunc) gst_dash_demux_index_entry_search, mode, &ts, NULL);
+  /* No exact match found, nothing in our index
+   * This is usually a bug or broken stream, as the seeking code already
+   * makes sure that we're in the correct period and segment, and only need
+   * to find the correct place inside the segment. Allow for some rounding
+   * errors and inaccuracies here though */
+  if (!entry) {
+    GstSidxBoxEntry *last_entry = &sidx->entries[sidx->entries_count - 1];
 
-    if (entry) {
-      idx = entry - sidx->entries;
-    } else if (mode == GST_SEARCH_MODE_BEFORE) {
-      /* target ts is smaller than pts of the first entry */
-      idx = 0;
-    } else {
-      /* target ts is larger than pts + duration of the last entry
-       * idx = sidx->entries_count */
-    }
+    GST_WARNING_OBJECT (dashstream->parent.pad, "Couldn't find SIDX entry");
 
-    /* FIXME in reverse mode, if we are exactly at a fragment start it makes more
-     * sense to start from the end of the previous fragment */
-    /* FIXME we should have a GST_SEARCH_MODE_NEAREST */
-    if ((flags & GST_SEEK_FLAG_SNAP_NEAREST) == GST_SEEK_FLAG_SNAP_NEAREST &&
-        idx + 1 < sidx->entries_count) {
-      if (ABS (sidx->entries[idx + 1].pts - ts) <
-          ABS (sidx->entries[idx].pts - ts))
-        idx += 1;
-    }
+    if (ts < sidx->entries[0].pts
+        && ts + 250 * GST_MSECOND >= sidx->entries[0].pts)
+      entry = &sidx->entries[0];
+    else if (ts >= last_entry->pts + last_entry->duration &&
+        ts < last_entry->pts + last_entry->duration + 250 * GST_MSECOND)
+      entry = last_entry;
   }
+  if (!entry)
+    return GST_FLOW_EOS;
+
+  idx = entry - sidx->entries;
+
+  /* FIXME in reverse mode, if we are exactly at a fragment start it makes more
+   * sense to start from the end of the previous fragment */
+
+  /* Now entry->pts <= ts < entry->pts + entry->duration, need to adjust for
+   * snapping */
+  if ((flags & GST_SEEK_FLAG_SNAP_NEAREST) == GST_SEEK_FLAG_SNAP_NEAREST) {
+    if (idx + 1 < sidx->entries_count
+        && ABS (sidx->entries[idx + 1].pts - ts) <
+        ABS (sidx->entries[idx].pts - ts))
+      idx += 1;
+  } else if ((forward && (flags & GST_SEEK_FLAG_SNAP_AFTER)) || (!forward
+          && (flags & GST_SEEK_FLAG_SNAP_BEFORE))) {
+    if (idx + 1 < sidx->entries_count && entry->pts < ts)
+      idx += 1;
+  }
+
+  g_assert (sidx->entry_index < sidx->entries_count);
 
   sidx->entry_index = idx;
-  if (idx == sidx->entries_count)
-    dashstream->sidx_position =
-        sidx->entries[idx - 1].pts + sidx->entries[idx - 1].duration;
-  else
-    dashstream->sidx_position = sidx->entries[idx].pts;
+  dashstream->sidx_position = sidx->entries[idx].pts;
 
-  if (final_ts) {
+  if (final_ts)
     *final_ts = dashstream->sidx_position;
-  }
+
+  return ret;
 }
 
 static GstFlowReturn
@@ -1343,13 +1351,13 @@ gst_dash_demux_stream_seek (GstAdaptiveDemuxStream * stream, gboolean forward,
     }
 
     if (dashstream->sidx_parser.status == GST_ISOFF_SIDX_PARSER_FINISHED) {
-      gst_dash_demux_stream_sidx_seek (dashstream, forward, flags, ts,
-          final_ts);
-      if (SIDX (dashstream)->entry_index >= SIDX (dashstream)->entries_count) {
+      if (gst_dash_demux_stream_sidx_seek (dashstream, forward, flags, ts,
+              final_ts) != GST_FLOW_OK) {
         GST_ERROR_OBJECT (stream->pad, "Couldn't find position in sidx");
         dashstream->sidx_position = GST_CLOCK_TIME_NONE;
         gst_isoff_sidx_parser_clear (&dashstream->sidx_parser);
       }
+      dashstream->pending_seek_ts = GST_CLOCK_TIME_NONE;
     } else {
       /* no index yet, seek when we have it */
       /* FIXME - the final_ts won't be correct here */
@@ -2282,10 +2290,9 @@ gst_dash_demux_parse_isobmff (GstAdaptiveDemux * demux,
 
         if (GST_CLOCK_TIME_IS_VALID (dash_stream->pending_seek_ts)) {
           /* FIXME, preserve seek flags */
-          gst_dash_demux_stream_sidx_seek (dash_stream,
-              demux->segment.rate >= 0, 0, dash_stream->pending_seek_ts, NULL);
-          if (SIDX (dash_stream)->entry_index >=
-              SIDX (dash_stream)->entries_count) {
+          if (gst_dash_demux_stream_sidx_seek (dash_stream,
+                  demux->segment.rate >= 0, 0, dash_stream->pending_seek_ts,
+                  NULL) != GST_FLOW_OK) {
             GST_ERROR_OBJECT (stream->pad, "Couldn't find position in sidx");
             dash_stream->sidx_position = GST_CLOCK_TIME_NONE;
             gst_isoff_sidx_parser_clear (&dash_stream->sidx_parser);
@@ -2764,16 +2771,14 @@ gst_dash_demux_data_received (GstAdaptiveDemux * demux,
         if (dash_stream->sidx_parser.status == GST_ISOFF_SIDX_PARSER_FINISHED) {
           if (GST_CLOCK_TIME_IS_VALID (dash_stream->pending_seek_ts)) {
             /* FIXME, preserve seek flags */
-            gst_dash_demux_stream_sidx_seek (dash_stream,
-                demux->segment.rate >= 0, 0, dash_stream->pending_seek_ts,
-                NULL);
-            dash_stream->pending_seek_ts = GST_CLOCK_TIME_NONE;
-            if (SIDX (dash_stream)->entry_index >=
-                SIDX (dash_stream)->entries_count) {
+            if (gst_dash_demux_stream_sidx_seek (dash_stream,
+                    demux->segment.rate >= 0, 0, dash_stream->pending_seek_ts,
+                    NULL) != GST_FLOW_OK) {
               GST_ERROR_OBJECT (stream->pad, "Couldn't find position in sidx");
               dash_stream->sidx_position = GST_CLOCK_TIME_NONE;
               gst_isoff_sidx_parser_clear (&dash_stream->sidx_parser);
             }
+            dash_stream->pending_seek_ts = GST_CLOCK_TIME_NONE;
           } else {
             gint idx = 0;