oggdemux: fix timestamps after seek

After a seek, discard all packets before the packet with the granulepos on it so
that the output buffers contain valid timestamps.

Reorder some code so that we check the timestamps before allocating and pushing
an output buffer.

Do more checks on valid packets in ogm mode.

1 files changed, 73 insertions, 53 deletions

diff --git a/ext/ogg/gstoggdemux.c b/ext/ogg/gstoggdemux.c
index a73151dda..e50c90ef5 100644
--- a/ext/ogg/gstoggdemux.c
+++ b/ext/ogg/gstoggdemux.c
@@ -462,16 +462,23 @@ gst_ogg_demux_chain_peer (GstOggPad * pad, ogg_packet * packet)
   gint64 current_time;
   GstOggChain *chain;
   gint64 duration;
-  int offset;
-  int trim;
+  gint offset;
+  gint trim;
+  GstClockTime out_timestamp, out_duration;
+  guint64 out_offset, out_offset_end;
 
   GST_DEBUG_OBJECT (ogg,
       "%p streaming to peer serial %08x", pad, pad->map.serialno);
 
   if (pad->map.is_ogm) {
     const guint8 *data;
+    long bytes;
 
     data = packet->packet;
+    bytes = packet->bytes;
+
+    if (bytes < 1)
+      goto empty_packet;
 
     if (data[0] & 1) {
       /* We don't push header packets for OGM */
@@ -481,86 +488,87 @@ gst_ogg_demux_chain_peer (GstOggPad * pad, ogg_packet * packet)
 
     offset = 1 + (((data[0] & 0xc0) >> 6) | ((data[0] & 0x02) << 1));
 
-    if (offset > packet->bytes) {
-      GST_ERROR ("buffer too small");
-      //goto buffer_too_small;
-    }
-    if (pad->map.is_ogm) {
-      trim = 0;
-      while (data[packet->bytes - 1 - trim] == 0) {
-        trim++;
-      }
-    } else {
-      trim = 0;
+    trim = 0;
+    while (bytes && data[bytes - 1] == 0) {
+      trim++;
+      bytes--;
     }
   } else {
     offset = 0;
     trim = 0;
   }
 
-  ret =
-      gst_pad_alloc_buffer_and_set_caps (GST_PAD_CAST (pad),
-      GST_BUFFER_OFFSET_NONE, packet->bytes - offset - trim,
-      GST_PAD_CAPS (pad), &buf);
-
-  /* combine flows */
-  cret = gst_ogg_demux_combine_flows (ogg, pad, ret);
-  if (ret != GST_FLOW_OK)
-    goto no_buffer;
-
-  /* copy packet in buffer */
-  memcpy (buf->data, packet->packet + offset, packet->bytes - offset - trim);
-
+  /* get timing info for the packet */
   duration = gst_ogg_stream_get_packet_duration (&pad->map, packet);
-
-  GST_DEBUG_OBJECT (ogg, "duration %" G_GUINT64_FORMAT, duration);
+  GST_DEBUG_OBJECT (ogg, "packet duration %" G_GUINT64_FORMAT, duration);
 
   if (packet->b_o_s) {
-    GST_BUFFER_TIMESTAMP (buf) = GST_CLOCK_TIME_NONE;
-    GST_BUFFER_DURATION (buf) = GST_CLOCK_TIME_NONE;
-    GST_BUFFER_OFFSET (buf) = 0;
-    GST_BUFFER_OFFSET_END (buf) = -1;
+    out_timestamp = GST_CLOCK_TIME_NONE;
+    out_duration = GST_CLOCK_TIME_NONE;
+    out_offset = 0;
+    out_offset_end = -1;
   } else {
-    if (pad->current_granule != -1)
-      pad->current_granule += duration;
     if (packet->granulepos != -1) {
       pad->current_granule = gst_ogg_stream_granulepos_to_granule (&pad->map,
           packet->granulepos);
       pad->keyframe_granule =
           gst_ogg_stream_granulepos_to_key_granule (&pad->map,
           packet->granulepos);
+      GST_DEBUG_OBJECT (ogg, "new granule %" G_GUINT64_FORMAT,
+          pad->current_granule);
+    } else if (pad->current_granule != -1) {
+      pad->current_granule += duration;
+      GST_DEBUG_OBJECT (ogg, "interpollating granule %" G_GUINT64_FORMAT,
+          pad->current_granule);
     }
-    GST_DEBUG_OBJECT (ogg, "current granule %" G_GUINT64_FORMAT,
-        pad->current_granule);
+    /* we only push buffers after we have a valid granule. This is done so that
+     * we nicely skip packets without a timestamp after a seek. This is ok
+     * because we base or seek on the packet after the page with the smaller
+     * timestamp. */
+    if (pad->current_granule == -1)
+      goto no_timestamp;
 
     if (pad->map.is_ogm) {
-      GST_BUFFER_TIMESTAMP (buf) = gst_ogg_stream_granule_to_time (&pad->map,
+      out_timestamp = gst_ogg_stream_granule_to_time (&pad->map,
           pad->current_granule);
-      GST_BUFFER_DURATION (buf) = gst_util_uint64_scale (duration,
+      out_duration = gst_util_uint64_scale (duration,
           GST_SECOND * pad->map.granulerate_d, pad->map.granulerate_n);
     } else {
-      guint64 endtime;
-
-      GST_BUFFER_TIMESTAMP (buf) = gst_ogg_stream_granule_to_time (&pad->map,
+      out_timestamp = gst_ogg_stream_granule_to_time (&pad->map,
           pad->current_granule - duration);
-      GST_DEBUG_OBJECT (ogg, "current granule time %" GST_TIME_FORMAT,
-          GST_TIME_ARGS (GST_BUFFER_TIMESTAMP (buf)));
-      endtime =
-          gst_ogg_stream_granule_to_time (&pad->map, pad->current_granule);
-      GST_DEBUG_OBJECT (ogg, "current granule end time %" GST_TIME_FORMAT,
-          GST_TIME_ARGS (endtime));
-
-      GST_BUFFER_DURATION (buf) = endtime - GST_BUFFER_TIMESTAMP (buf);
-      GST_DEBUG_OBJECT (ogg, "current duration %" GST_TIME_FORMAT,
-          GST_TIME_ARGS (GST_BUFFER_DURATION (buf)));
+      out_duration =
+          gst_ogg_stream_granule_to_time (&pad->map,
+          pad->current_granule) - out_timestamp;
     }
-    GST_BUFFER_OFFSET_END (buf) =
+    out_offset_end =
         gst_ogg_stream_granule_to_granulepos (&pad->map, pad->current_granule,
         pad->keyframe_granule);
-    GST_BUFFER_OFFSET (buf) =
+    out_offset =
         gst_ogg_stream_granule_to_time (&pad->map, pad->current_granule);
   }
 
+  /* check for invalid buffer sizes */
+  if (G_UNLIKELY (offset + trim >= packet->bytes))
+    goto empty_packet;
+
+  ret =
+      gst_pad_alloc_buffer_and_set_caps (GST_PAD_CAST (pad),
+      GST_BUFFER_OFFSET_NONE, packet->bytes - offset - trim,
+      GST_PAD_CAPS (pad), &buf);
+
+  /* combine flows */
+  cret = gst_ogg_demux_combine_flows (ogg, pad, ret);
+  if (ret != GST_FLOW_OK)
+    goto no_buffer;
+
+  /* copy packet in buffer */
+  memcpy (buf->data, packet->packet + offset, packet->bytes - offset - trim);
+
+  GST_BUFFER_TIMESTAMP (buf) = out_timestamp;
+  GST_BUFFER_DURATION (buf) = out_duration;
+  GST_BUFFER_OFFSET (buf) = out_offset;
+  GST_BUFFER_OFFSET_END (buf) = out_offset_end;
+
   /* Mark discont on the buffer */
   if (pad->discont) {
     GST_BUFFER_FLAG_SET (buf, GST_BUFFER_FLAG_DISCONT);
@@ -614,6 +622,18 @@ done:
   return cret;
 
   /* special cases */
+empty_packet:
+  {
+    GST_DEBUG_OBJECT (ogg, "Skipping empty packet");
+    cret = gst_ogg_demux_combine_flows (ogg, pad, GST_FLOW_OK);
+    goto done;
+  }
+no_timestamp:
+  {
+    GST_DEBUG_OBJECT (ogg, "skipping packet: no valid granule found yet");
+    cret = gst_ogg_demux_combine_flows (ogg, pad, GST_FLOW_OK);
+    goto done;
+  }
 no_buffer:
   {
     GST_DEBUG_OBJECT (ogg,