From 7ca6d9634a8df45e9ad28f572e36a8d5e697b413 Mon Sep 17 00:00:00 2001
From: Mathieu Duponchelle <mathieu.duponchelle@opencreed.com>
Date: Thu, 12 Feb 2015 22:06:17 +0100
Subject: [PATCH] dashdemux: Fix handling of live streams with timeshift
 buffers.

By implementing get_live_seek_range.

As shown by :

gst-validate-1.0 playbin \
uri=http://dev-iplatforms.kw.bbc.co.uk/dash/news24-avc3/news24.php

This patch handles live seeking, by setting a live seek range
comprised between now - timeShiftBufferDepth and now.

The inteersting thing with this stream is that one can actually
ask fragments up to availabilityStartTime, but it seems quite clear
in the spec that content is only guaranteed to exist up to
timeShiftBufferDepth.

One can test live seeking this way :

gst-validate-1.0 playbin \
uri=http://dev-iplatforms.kw.bbc.co.uk/dash/news24-avc3/news24.php \
--set-scenario seek_back.scenario

with scenario being:

description, seek=true
seek, playback-time=position+5.0, start="position-600.0",
flags=accurate+flush

This example will play the stream, wait for five seconds, then seek back
to a position 10 minutes earlier.

https://bugzilla.gnome.org/show_bug.cgi?id=744362
---
 ext/dash/gstdashdemux.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/ext/dash/gstdashdemux.c b/ext/dash/gstdashdemux.c
index 12f5d6069a..fca120c1b5 100644
--- a/ext/dash/gstdashdemux.c
+++ b/ext/dash/gstdashdemux.c
@@ -262,6 +262,25 @@ gst_dash_demux_dispose (GObject * obj)
   G_OBJECT_CLASS (parent_class)->dispose (obj);
 }
 
+static gboolean
+gst_dash_demux_get_live_seek_range (GstAdaptiveDemux * demux, gint64 * start,
+    gint64 * stop)
+{
+  GstDashDemux *self = GST_DASH_DEMUX (demux);
+  GDateTime *now = g_date_time_new_now_utc ();
+  GDateTime *mstart =
+      gst_date_time_to_g_date_time (self->client->mpd_node->availabilityStartTime);
+  GTimeSpan stream_now;
+
+  stream_now = g_date_time_difference (now, mstart);
+  g_date_time_unref (now);
+  g_date_time_unref (mstart);
+  *stop = stream_now * GST_USECOND;
+
+  *start = *stop - (self->client->mpd_node->timeShiftBufferDepth * GST_MSECOND);
+  return TRUE;
+}
+
 static void
 gst_dash_demux_class_init (GstDashDemuxClass * klass)
 {
@@ -338,6 +357,7 @@ gst_dash_demux_class_init (GstDashDemuxClass * klass)
   gstadaptivedemux_class->stream_update_fragment_info =
       gst_dash_demux_stream_update_fragment_info;
   gstadaptivedemux_class->stream_free = gst_dash_demux_stream_free;
+  gstadaptivedemux_class->get_live_seek_range = gst_dash_demux_get_live_seek_range;
 }
 
 static void