From 08643993df1b71719551a8614dd68b2d4ea489eb Mon Sep 17 00:00:00 2001
From: Nicolas Dufresne <nicolas.dufresne@collabora.com>
Date: Fri, 14 Jul 2017 16:21:38 -0400
Subject: [PATCH] v4l2object: Only check CROPCAP for par once

The pixel aspect ratio is documented to not change unless the TV
Standard is changed. So this mean that this will be uniform across all
possible format and resolutions.

https://bugzilla.gnome.org/show_bug.cgi?id=784674
---
 sys/v4l2/gstv4l2object.c | 57 ++++++++++++++++++------------------------------
 1 file changed, 21 insertions(+), 36 deletions(-)

diff --git a/sys/v4l2/gstv4l2object.c b/sys/v4l2/gstv4l2object.c
index ca4e710..6f7d8dd 100644
--- a/sys/v4l2/gstv4l2object.c
+++ b/sys/v4l2/gstv4l2object.c
@@ -1821,42 +1821,8 @@ gst_v4l2_object_get_nearest_size (GstV4l2Object * v4l2object,
 static void
 gst_v4l2_object_add_aspect_ratio (GstV4l2Object * v4l2object, GstStructure * s)
 {
-  struct v4l2_cropcap cropcap;
-  int num = 1, den = 1;
-
-  if (!v4l2object->keep_aspect)
-    return;
-
-  if (v4l2object->par) {
-    num = gst_value_get_fraction_numerator (v4l2object->par);
-    den = gst_value_get_fraction_denominator (v4l2object->par);
-    goto done;
-  }
-
-  memset (&cropcap, 0, sizeof (cropcap));
-
-  cropcap.type = v4l2object->type;
-  if (v4l2_ioctl (v4l2object->video_fd, VIDIOC_CROPCAP, &cropcap) < 0)
-    goto cropcap_failed;
-
-  num = cropcap.pixelaspect.numerator;
-  den = cropcap.pixelaspect.denominator;
-
-  /* Ignore PAR that are 0/0 */
-  if (den == 0)
-    return;
-
-done:
-  gst_structure_set (s, "pixel-aspect-ratio", GST_TYPE_FRACTION, num, den,
-      NULL);
-  return;
-
-cropcap_failed:
-  if (errno != ENOTTY)
-    GST_WARNING_OBJECT (v4l2object->element,
-        "Failed to probe pixel aspect ratio with VIDIOC_CROPCAP: %s",
-        g_strerror (errno));
-  goto done;
+  if (v4l2object->keep_aspect && v4l2object->par)
+    gst_structure_set_value (s, "pixel-aspect-ratio", v4l2object->par);
 }
 
 /* returns TRUE if the value was changed in place, otherwise FALSE */
@@ -3913,6 +3879,25 @@ gst_v4l2_object_probe_caps (GstV4l2Object * v4l2object, GstCaps * filter)
 
   ret = gst_caps_new_empty ();
 
+  if (v4l2object->keep_aspect && !v4l2object->par) {
+    struct v4l2_cropcap cropcap;
+
+    memset (&cropcap, 0, sizeof (cropcap));
+
+    cropcap.type = v4l2object->type;
+    if (v4l2_ioctl (v4l2object->video_fd, VIDIOC_CROPCAP, &cropcap) < 0) {
+      if (errno != ENOTTY)
+        GST_WARNING_OBJECT (v4l2object->element,
+            "Failed to probe pixel aspect ratio with VIDIOC_CROPCAP: %s",
+            g_strerror (errno));
+    } else {
+      v4l2object->par = g_new0 (GValue, 1);
+      g_value_init (v4l2object->par, GST_TYPE_FRACTION);
+      gst_value_set_fraction (v4l2object->par, cropcap.pixelaspect.numerator,
+          cropcap.pixelaspect.denominator);
+    }
+  }
+
   for (walk = formats; walk; walk = walk->next) {
     struct v4l2_fmtdesc *format;
     GstStructure *template;
-- 
2.7.4