Merge branch 'asfdemux-scan-duration' into 'main'

Draft: asfdemux: scan last packet to determine duration for files saved from broadcasts

Closes #2633

See merge request gstreamer/gstreamer!1778

subprojects/gst-plugins-ugly/gst/asfdemux/asfpacket.c

@@ -27,6 +27,7 @@
 
 #include <gst/gstutils.h>
 #include <gst/gstinfo.h>
+#include <gst/base/gstbytereader.h>
 #include <string.h>
 
 #define GST_ASF_PAYLOAD_KF_COMPLETE(stream, payload) (stream->is_video && payload->keyframe && payload->buf_filled >= payload->mo_size)
@@ -806,3 +807,61 @@ done:
   gst_buffer_unmap (buf, &map);
   return ret;
 }
+
+gboolean
+gst_asf_packet_get_packet_times (GstASFDemux * demux, GstBuffer * buf,
+    GstClockTime * send_time, GstClockTime * duration)
+{
+  static const guint lens[4] = { 0, 1, 2, 4 };
+  GstByteReader br;
+  GstMapInfo map;
+  gboolean ret = FALSE;
+  guint8 ec_flags, flags1, len;
+
+  gst_buffer_map (buf, &map, GST_MAP_READ);
+
+  gst_byte_reader_init (&br, map.data, map.size);
+
+  /* need at least two payload flag bytes, send time, and duration */
+  if (gst_byte_reader_get_remaining (&br) < 1 + 1 + 4 + 2)
+    goto done;
+
+  ec_flags = gst_byte_reader_get_uint8_unchecked (&br);
+
+  /* skip optional error correction stuff */
+  if ((ec_flags & 0x80) != 0) {
+    guint ec_len_type, ec_len;
+
+    ec_len_type = (ec_flags & 0x60) >> 5;
+    if (ec_len_type == 0) {
+      ec_len = ec_flags & 0x0f;
+    } else {
+      ec_len = 2;
+    }
+    if (!gst_byte_reader_skip (&br, ec_len))
+      goto done;
+  }
+
+  /* parse payload info */
+  if (!gst_byte_reader_get_uint8 (&br, &flags1) ||
+      !gst_byte_reader_skip (&br, 1))
+    goto done;
+
+  len = lens[(flags1 >> 1) & 0x03];     /* sequence len */
+  len += lens[(flags1 >> 3) & 0x03];    /* padding len  */
+  len += lens[(flags1 >> 5) & 0x03];    /* length len   */
+
+  if (!gst_byte_reader_skip (&br, len))
+    goto done;
+
+  if (gst_byte_reader_get_remaining (&br) < 4 + 2)
+    goto done;
+
+  *send_time = gst_byte_reader_get_uint32_le_unchecked (&br) * GST_MSECOND;
+  *duration = gst_byte_reader_get_uint16_le_unchecked (&br) * GST_MSECOND;
+  ret = TRUE;
+
+done:
+  gst_buffer_unmap (buf, &map);
+  return ret;
+}

subprojects/gst-plugins-ugly/gst/asfdemux/asfpacket.h

@@ -65,6 +65,11 @@ typedef enum {
 
 GstAsfDemuxParsePacketError gst_asf_demux_parse_packet (GstASFDemux * demux, GstBuffer * buf);
 
+gboolean                    gst_asf_packet_get_packet_times (GstASFDemux   * demux,
+                                                             GstBuffer     * buf,
+                                                             GstClockTime  * send_time,
+                                                             GstClockTime  * duration);
+
 #define gst_asf_payload_is_complete(payload) \
     ((payload)->buf_filled >= (payload)->mo_size)
 

subprojects/gst-plugins-ugly/gst/asfdemux/gstasfdemux.c

@@ -1150,6 +1150,73 @@ gst_asf_demux_pull_indices (GstASFDemux * demux)
   return ret;
 }
 
+static gboolean
+gst_asf_demux_scan_peek_packet_times (GstASFDemux * demux, guint n,
+    GstClockTime * send_time, GstClockTime * duration)
+{
+  GstBuffer *buf = NULL;
+
+  if (!gst_asf_demux_pull_data (demux,
+          demux->data_offset + (n * demux->packet_size), demux->packet_size,
+          &buf, NULL))
+    return FALSE;
+
+  if (!gst_asf_packet_get_packet_times (demux, buf, send_time, duration)) {
+    GST_WARNING_OBJECT (demux, "Couldn't extract send time from packet %u", n);
+    gst_buffer_unref (buf);
+    return FALSE;
+  }
+
+  GST_INFO_OBJECT (demux, "packet %u: send time %" GST_TIME_FORMAT
+      ", duration %" GST_TIME_FORMAT, n, GST_TIME_ARGS (*send_time),
+      GST_TIME_ARGS (*duration));
+
+  gst_buffer_unref (buf);
+  return TRUE;
+}
+
+static gboolean
+gst_asf_demux_scan_for_duration (GstASFDemux * demux)
+{
+  GstClockTime start, stop, duration;
+  gint64 size = 0;
+  guint num_packets, last;
+
+  if (!gst_pad_peer_query_duration (demux->sinkpad, GST_FORMAT_BYTES, &size))
+    return FALSE;
+
+  GST_INFO_OBJECT (demux, "file size   %" G_GINT64_FORMAT, size);
+  GST_INFO_OBJECT (demux, "data offset %" G_GUINT64_FORMAT, demux->data_offset);
+  GST_INFO_OBJECT (demux, "packet size %u", demux->packet_size);
+
+  if (size <= demux->data_offset)
+    return FALSE;
+
+  num_packets = (size - demux->data_offset) / demux->packet_size;
+  GST_INFO_OBJECT (demux, "num_packets = %u (calculated)", num_packets);
+
+  if (num_packets < 10)         /* arbitrary value */
+    return FALSE;
+
+  if (!gst_asf_demux_scan_peek_packet_times (demux, 0, &start, &duration))
+    return FALSE;
+
+  last = num_packets - 1;
+  if (!gst_asf_demux_scan_peek_packet_times (demux, last, &stop, &duration))
+    return FALSE;
+
+  if (GST_CLOCK_TIME_IS_VALID (duration))
+    stop += duration;
+
+  demux->num_packets = num_packets;
+  demux->play_time = stop - start;
+  demux->segment.duration = stop - start;
+  GST_INFO_OBJECT (demux, "scanned duration: %" GST_TIME_FORMAT,
+      GST_TIME_ARGS (demux->play_time));
+  return TRUE;
+}
+
+
 static gboolean
 gst_asf_demux_parse_data_object_start (GstASFDemux * demux, guint8 * data)
 {
@@ -1182,6 +1249,11 @@ gst_asf_demux_parse_data_object_start (GstASFDemux * demux, guint8 * data)
     demux->num_packets = GST_READ_UINT64_LE (data + (16 + 8) + 16);
   } else {
     demux->num_packets = 0;
+
+    if (!demux->streaming) {
+      if (!gst_asf_demux_scan_for_duration (demux))
+        GST_WARNING_OBJECT (demux, "couldn't determine duration");
+    }
   }
 
   if (demux->num_packets == 0)