[gst-cvs] gst-plugins-good: goom: add latency compensation code.

[Wim Taymans]

Module: gst-plugins-good
Branch: master
Commit: 418eae3ee33bddda6ed94eb6c089b8276898fcc8
URL:    http://cgit.freedesktop.org/gstreamer/gst-plugins-good/commit/?id=418eae3ee33bddda6ed94eb6c089b8276898fcc8

Author: Wim Taymans <wim.taymans at collabora.co.uk>
Date:   Mon Oct  4 18:52:14 2010 +0200

goom: add latency compensation code.

Implement a latency query and report how much latency we will add to the
stream.
Alse make some defaults for the default width/height/framerate

Fixes #631303

---

 gst/goom/gstgoom.c |   81 +++++++++++++++++++++++++++++++++++++++++++++++----
 1 files changed, 74 insertions(+), 7 deletions(-)

diff --git a/gst/goom/gstgoom.c b/gst/goom/gstgoom.c
index 50f357a..8895283 100644
--- a/gst/goom/gstgoom.c
+++ b/gst/goom/gstgoom.c
@@ -50,6 +50,11 @@
 GST_DEBUG_CATEGORY (goom_debug);
 #define GST_CAT_DEFAULT goom_debug
 
+#define DEFAULT_WIDTH  320
+#define DEFAULT_HEIGHT 240
+#define DEFAULT_FPS_N  25
+#define DEFAULT_FPS_D  1
+
 /* signals and args */
 enum
 {
@@ -93,6 +98,8 @@ static GstFlowReturn gst_goom_chain (GstPad * pad, GstBuffer * buffer);
 static gboolean gst_goom_src_event (GstPad * pad, GstEvent * event);
 static gboolean gst_goom_sink_event (GstPad * pad, GstEvent * event);
 
+static gboolean gst_goom_src_query (GstPad * pad, GstQuery * query);
+
 static gboolean gst_goom_sink_setcaps (GstPad * pad, GstCaps * caps);
 static gboolean gst_goom_src_setcaps (GstPad * pad, GstCaps * caps);
 
@@ -170,14 +177,16 @@ gst_goom_init (GstGoom * goom)
       GST_DEBUG_FUNCPTR (gst_goom_src_setcaps));
   gst_pad_set_event_function (goom->srcpad,
       GST_DEBUG_FUNCPTR (gst_goom_src_event));
+  gst_pad_set_query_function (goom->srcpad,
+      GST_DEBUG_FUNCPTR (gst_goom_src_query));
   gst_element_add_pad (GST_ELEMENT (goom), goom->srcpad);
 
   goom->adapter = gst_adapter_new ();
 
-  goom->width = 320;
-  goom->height = 200;
-  goom->fps_n = 25;             /* desired frame rate */
-  goom->fps_d = 1;              /* desired frame rate */
+  goom->width = DEFAULT_WIDTH;
+  goom->height = DEFAULT_HEIGHT;
+  goom->fps_n = DEFAULT_FPS_N;  /* desired frame rate */
+  goom->fps_d = DEFAULT_FPS_D;  /* desired frame rate */
   goom->channels = 0;
   goom->rate = 0;
   goom->duration = 0;
@@ -287,9 +296,10 @@ gst_goom_src_negotiate (GstGoom * goom)
   }
 
   structure = gst_caps_get_structure (target, 0);
-  gst_structure_fixate_field_nearest_int (structure, "width", 320);
-  gst_structure_fixate_field_nearest_int (structure, "height", 240);
-  gst_structure_fixate_field_nearest_fraction (structure, "framerate", 30, 1);
+  gst_structure_fixate_field_nearest_int (structure, "width", DEFAULT_WIDTH);
+  gst_structure_fixate_field_nearest_int (structure, "height", DEFAULT_HEIGHT);
+  gst_structure_fixate_field_nearest_fraction (structure, "framerate",
+      DEFAULT_FPS_N, DEFAULT_FPS_D);
 
   gst_pad_set_caps (goom->srcpad, target);
   gst_caps_unref (target);
@@ -388,6 +398,63 @@ gst_goom_sink_event (GstPad * pad, GstEvent * event)
   return res;
 }
 
+static gboolean
+gst_goom_src_query (GstPad * pad, GstQuery * query)
+{
+  gboolean res;
+  GstGoom *goom;
+
+  goom = GST_GOOM (gst_pad_get_parent (pad));
+
+  switch (GST_QUERY_TYPE (query)) {
+    case GST_QUERY_LATENCY:
+    {
+      /* We need to send the query upstream and add the returned latency to our
+       * own */
+      GstClockTime min_latency, max_latency;
+      gboolean us_live;
+      GstClockTime our_latency;
+      guint max_samples;
+
+      if ((res = gst_pad_peer_query (goom->sinkpad, query))) {
+        gst_query_parse_latency (query, &us_live, &min_latency, &max_latency);
+
+        GST_DEBUG_OBJECT (goom, "Peer latency: min %"
+            GST_TIME_FORMAT " max %" GST_TIME_FORMAT,
+            GST_TIME_ARGS (min_latency), GST_TIME_ARGS (max_latency));
+
+        /* the max samples we must buffer buffer */
+        max_samples = MAX (GOOM_SAMPLES, goom->spf);
+        our_latency =
+            gst_util_uint64_scale_int (max_samples, GST_SECOND, goom->rate);
+
+        GST_DEBUG_OBJECT (goom, "Our latency: %" GST_TIME_FORMAT,
+            GST_TIME_ARGS (our_latency));
+
+        /* we add some latency but only if we need to buffer more than what
+         * upstream gives us */
+        min_latency = MAX (our_latency, min_latency);
+        if (max_latency != -1)
+          max_latency = MAX (our_latency, max_latency);
+
+        GST_DEBUG_OBJECT (goom, "Calculated total latency : min %"
+            GST_TIME_FORMAT " max %" GST_TIME_FORMAT,
+            GST_TIME_ARGS (min_latency), GST_TIME_ARGS (max_latency));
+
+        gst_query_set_latency (query, TRUE, min_latency, max_latency);
+      }
+      break;
+    }
+    default:
+      res = gst_pad_peer_query (goom->sinkpad, query);
+      break;
+  }
+
+  gst_object_unref (goom);
+
+  return res;
+}
+
 static GstFlowReturn
 get_buffer (GstGoom * goom, GstBuffer ** outbuf)
 {