From b673e375463411bd5ce00ac5cdb6bcc438446bdd Mon Sep 17 00:00:00 2001
From: =?utf8?q?Sebastian=20Dr=C3=B6ge?= <sebastian.droege@collabora.co.uk>
Date: Fri, 12 Aug 2011 12:25:03 +0200
Subject: [PATCH] basevideoencoder: Proxy the width/height/framerate/PAR
 constraints of downstream caps to upstream

This allows to specify constraints on the compressed downstream caps
by muxers or capsfilters, which will then be forwarded to upstream
and allows video converters to fulfill the constraints.

Code based on Mark Nauwelaerts audio encoder base class.
---
 omx/gstbasevideoencoder.c | 71 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 71 insertions(+)

diff --git a/omx/gstbasevideoencoder.c b/omx/gstbasevideoencoder.c
index 7e96e1f..88d8c72 100644
--- a/omx/gstbasevideoencoder.c
+++ b/omx/gstbasevideoencoder.c
@@ -117,6 +117,7 @@ static void gst_base_video_encoder_finalize (GObject * object);
 
 static gboolean gst_base_video_encoder_sink_setcaps (GstPad * pad,
     GstCaps * caps);
+static GstCaps *gst_base_video_encoder_sink_getcaps (GstPad * pad);
 static gboolean gst_base_video_encoder_src_event (GstPad * pad,
     GstEvent * event);
 static gboolean gst_base_video_encoder_sink_event (GstPad * pad,
@@ -210,6 +211,8 @@ gst_base_video_encoder_init (GstBaseVideoEncoder * base_video_encoder,
       GST_DEBUG_FUNCPTR (gst_base_video_encoder_sink_event));
   gst_pad_set_setcaps_function (pad,
       GST_DEBUG_FUNCPTR (gst_base_video_encoder_sink_setcaps));
+  gst_pad_set_getcaps_function (pad,
+      GST_DEBUG_FUNCPTR (gst_base_video_encoder_sink_getcaps));
 
   pad = GST_BASE_VIDEO_CODEC_SRC_PAD (base_video_encoder);
 
@@ -358,6 +361,74 @@ exit:
   return ret;
 }
 
+static GstCaps *
+gst_base_video_encoder_sink_getcaps (GstPad * pad)
+{
+  GstBaseVideoEncoder *base_video_encoder;
+  const GstCaps *templ_caps;
+  GstCaps *allowed;
+  GstCaps *fcaps, *filter_caps;
+  gint i, j;
+
+  base_video_encoder = GST_BASE_VIDEO_ENCODER (gst_pad_get_parent (pad));
+
+  /* FIXME: Allow subclass to override this? */
+
+  /* Allow downstream to specify width/height/framerate/PAR constraints
+   * and forward them upstream for video converters to handle
+   */
+  templ_caps =
+      gst_pad_get_pad_template_caps (GST_BASE_VIDEO_CODEC_SINK_PAD
+      (base_video_encoder));
+  allowed =
+      gst_pad_get_allowed_caps (GST_BASE_VIDEO_CODEC_SRC_PAD
+      (base_video_encoder));
+  if (!allowed || gst_caps_is_empty (allowed) || gst_caps_is_any (allowed)) {
+    fcaps = gst_caps_copy (templ_caps);
+    goto done;
+  }
+
+  GST_LOG_OBJECT (base_video_encoder, "template caps %" GST_PTR_FORMAT,
+      templ_caps);
+  GST_LOG_OBJECT (base_video_encoder, "allowed caps %" GST_PTR_FORMAT, allowed);
+
+  filter_caps = gst_caps_new_empty ();
+
+  for (i = 0; i < gst_caps_get_size (templ_caps); i++) {
+    GQuark q_name =
+        gst_structure_get_name_id (gst_caps_get_structure (templ_caps, i));
+
+    for (j = 0; j < gst_caps_get_size (allowed); j++) {
+      const GstStructure *allowed_s = gst_caps_get_structure (allowed, j);
+      const GValue *val;
+      GstStructure *s;
+
+      s = gst_structure_id_empty_new (q_name);
+      if ((val = gst_structure_get_value (allowed_s, "width")))
+        gst_structure_set_value (s, "width", val);
+      if ((val = gst_structure_get_value (allowed_s, "height")))
+        gst_structure_set_value (s, "height", val);
+      if ((val = gst_structure_get_value (allowed_s, "framerate")))
+        gst_structure_set_value (s, "framerate", val);
+      if ((val = gst_structure_get_value (allowed_s, "pixel-aspect-ratio")))
+        gst_structure_set_value (s, "pixel-aspect-ratio", val);
+
+      gst_caps_merge_structure (filter_caps, s);
+    }
+  }
+
+  fcaps = gst_caps_intersect (filter_caps, templ_caps);
+  gst_caps_unref (filter_caps);
+
+done:
+
+  gst_caps_replace (&allowed, NULL);
+
+  GST_LOG_OBJECT (base_video_encoder, "Returning caps %" GST_PTR_FORMAT, fcaps);
+
+  return fcaps;
+}
+
 static void
 gst_base_video_encoder_finalize (GObject * object)
 {
-- 
2.7.4