From cb212c9fd7e41b74820eb096474bb5595865f2d0 Mon Sep 17 00:00:00 2001
From: Thibault Saunier <tsaunier@igalia.com>
Date: Tue, 28 Apr 2020 22:21:13 -0400
Subject: [PATCH] identity: Handle seeking with single_segment=True

Identity was ignoring seek and flush events even when using
a single segment. In the end it means that we couldn't compute
buffers running-time and stream time after seeks.

This commits adds support for flushing seeks only as I have no idea
what to do for non flushing ones.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/450>
---
 plugins/elements/gstidentity.c | 67 +++++++++++++++++++++++++++++++---
 plugins/elements/gstidentity.h |  1 +
 2 files changed, 62 insertions(+), 6 deletions(-)

diff --git a/plugins/elements/gstidentity.c b/plugins/elements/gstidentity.c
index ffa0756a0e..8ff19ac0a9 100644
--- a/plugins/elements/gstidentity.c
+++ b/plugins/elements/gstidentity.c
@@ -113,6 +113,8 @@ static void gst_identity_get_property (GObject * object, guint prop_id,
 
 static gboolean gst_identity_sink_event (GstBaseTransform * trans,
     GstEvent * event);
+static gboolean gst_identity_src_event (GstBaseTransform * trans,
+    GstEvent * event);
 static GstFlowReturn gst_identity_transform_ip (GstBaseTransform * trans,
     GstBuffer * buf);
 static gboolean gst_identity_start (GstBaseTransform * trans);
@@ -277,6 +279,7 @@ gst_identity_class_init (GstIdentityClass * klass)
       GST_DEBUG_FUNCPTR (gst_identity_change_state);
 
   gstbasetrans_class->sink_event = GST_DEBUG_FUNCPTR (gst_identity_sink_event);
+  gstbasetrans_class->src_event = GST_DEBUG_FUNCPTR (gst_identity_src_event);
   gstbasetrans_class->transform_ip =
       GST_DEBUG_FUNCPTR (gst_identity_transform_ip);
   gstbasetrans_class->start = GST_DEBUG_FUNCPTR (gst_identity_start);
@@ -420,7 +423,14 @@ gst_identity_sink_event (GstBaseTransform * trans, GstEvent * event)
 
       /* This is the first segment, send out a (0, -1) segment */
       gst_segment_init (&segment, segment.format);
+      if (identity->seek_segment.format != GST_FORMAT_UNDEFINED) {
+        segment.time = identity->seek_segment.time;
+        segment.base = identity->seek_segment.base;
+        gst_segment_init (&identity->seek_segment, GST_FORMAT_UNDEFINED);
+      }
+
       news = gst_event_new_segment (&segment);
+      GST_EVENT_SEQNUM (news) = GST_EVENT_SEQNUM (event);
 
       gst_pad_event_default (trans->sinkpad, GST_OBJECT_CAST (trans), news);
     } else {
@@ -459,8 +469,11 @@ gst_identity_sink_event (GstBaseTransform * trans, GstEvent * event)
     /* eat up segments */
     gst_event_unref (event);
     ret = TRUE;
-  } else {
-    if (GST_EVENT_TYPE (event) == GST_EVENT_FLUSH_START) {
+    goto done;
+  }
+
+  switch (GST_EVENT_TYPE (event)) {
+    case GST_EVENT_FLUSH_START:
       GST_OBJECT_LOCK (identity);
       identity->flushing = TRUE;
       g_cond_signal (&identity->blocked_cond);
@@ -469,18 +482,60 @@ gst_identity_sink_event (GstBaseTransform * trans, GstEvent * event)
         gst_clock_id_unschedule (identity->clock_id);
       }
       GST_OBJECT_UNLOCK (identity);
-    } else if (GST_EVENT_TYPE (event) == GST_EVENT_FLUSH_STOP) {
+      break;
+    case GST_EVENT_FLUSH_STOP:
       GST_OBJECT_LOCK (identity);
       identity->flushing = FALSE;
+      trans->have_segment = FALSE;
       GST_OBJECT_UNLOCK (identity);
-    }
-
-    ret = GST_BASE_TRANSFORM_CLASS (parent_class)->sink_event (trans, event);
+      break;
+    default:
+      break;
   }
 
+  ret = GST_BASE_TRANSFORM_CLASS (parent_class)->sink_event (trans, event);
+
+done:
   return ret;
 }
 
+static gboolean
+gst_identity_src_event (GstBaseTransform * trans, GstEvent * event)
+{
+  GstIdentity *identity = GST_IDENTITY (trans);
+
+  switch (GST_EVENT_TYPE (event)) {
+    case GST_EVENT_SEEK:
+    {
+      gdouble rate;
+      GstFormat fmt;
+      GstSeekFlags flags;
+      GstSeekType start_type, stop_type;
+      gint64 start, stop;
+      gst_event_parse_seek (event, &rate, &fmt, &flags, &start_type,
+          &start, &stop_type, &stop);
+
+      GST_OBJECT_LOCK (identity);
+      gst_segment_init (&identity->seek_segment, fmt);
+      if (!gst_segment_do_seek (&identity->seek_segment, rate, fmt,
+              flags, start_type, start, stop_type, stop, NULL)) {
+        GST_WARNING_OBJECT (identity, "Could not run seek %" GST_PTR_FORMAT,
+            event);
+        GST_OBJECT_UNLOCK (identity);
+
+        return FALSE;
+      }
+      GST_OBJECT_UNLOCK (identity);
+
+      break;
+    }
+    default:
+      break;
+  }
+
+  return GST_BASE_TRANSFORM_CLASS (parent_class)->src_event (trans, event);
+}
+
 static void
 gst_identity_check_imperfect_timestamp (GstIdentity * identity, GstBuffer * buf)
 {
diff --git a/plugins/elements/gstidentity.h b/plugins/elements/gstidentity.h
index 19bf29ffab..d81faaa677 100644
--- a/plugins/elements/gstidentity.h
+++ b/plugins/elements/gstidentity.h
@@ -67,6 +67,7 @@ struct _GstIdentity {
   gboolean 	 check_imperfect_timestamp;
   gboolean 	 check_imperfect_offset;
   gboolean	 single_segment;
+  GstSegment seek_segment;
   GstBufferFlags drop_buffer_flags;
   GstClockTime   prev_timestamp;
   GstClockTime   prev_duration;