v4l2object: set colorspace for output devices

When the v4l2 device is an output device, the application shall set the
colorspace. So map GStreamer colorimetry info to V4L2 colorspace and set
on set_format. In case we have no colorimetry information, we try to
guess it according to pixel format and video size.

https://bugzilla.gnome.org/show_bug.cgi?id=737579

diff --git a/sys/v4l2/gstv4l2object.c b/sys/v4l2/gstv4l2object.c
index b99bdbb..dd5c0a9 100644 (file)
--- a/sys/v4l2/gstv4l2object.c
+++ b/sys/v4l2/gstv4l2object.c
@@ -2538,6 +2538,7 @@ gst_v4l2_object_set_format (GstV4l2Object * v4l2object, GstCaps * caps)
   gint n_v4l_planes;
   gint i = 0;
   gboolean is_mplane, format_changed;
+  enum v4l2_colorspace colorspace = 0;
 
   GST_V4L2_CHECK_OPEN (v4l2object);
   GST_V4L2_CHECK_NOT_ACTIVE (v4l2object);
@@ -2573,6 +2574,28 @@ gst_v4l2_object_set_format (GstV4l2Object * v4l2object, GstCaps * caps)
     field = V4L2_FIELD_NONE;
   }
 
+  if (V4L2_TYPE_IS_OUTPUT (v4l2object->type)) {
+    /* We should set colorspace if we have it */
+    if (gst_video_colorimetry_matches (&info.colorimetry, "bt601")) {
+      colorspace = V4L2_COLORSPACE_SMPTE170M;
+    } else if (gst_video_colorimetry_matches (&info.colorimetry, "bt709")) {
+      colorspace = V4L2_COLORSPACE_REC709;
+    } else if (gst_video_colorimetry_matches (&info.colorimetry, "smpte240m")) {
+      colorspace = V4L2_COLORSPACE_SMPTE240M;
+    } else {
+      /* Try to guess colorspace according to pixelformat and size */
+      if (GST_VIDEO_INFO_IS_YUV (&info)) {
+        /* SD streams likely use SMPTE170M and HD streams REC709 */
+        if (width <= 720 && height <= 576)
+          colorspace = V4L2_COLORSPACE_SMPTE170M;
+        else
+          colorspace = V4L2_COLORSPACE_REC709;
+      } else if (GST_VIDEO_INFO_IS_RGB (&info)) {
+        colorspace = V4L2_COLORSPACE_SRGB;
+      }
+    }
+  }
+
   GST_DEBUG_OBJECT (v4l2object->element, "Desired format %dx%d, format "
       "%" GST_FOURCC_FORMAT " stride: %d", width, height,
       GST_FOURCC_ARGS (pixelformat), GST_VIDEO_INFO_PLANE_STRIDE (&info, 0));
@@ -2600,6 +2623,16 @@ gst_v4l2_object_set_format (GstV4l2Object * v4l2object, GstCaps * caps)
         format.fmt.pix_mp.height != height ||
         format.fmt.pix_mp.pixelformat != pixelformat ||
         format.fmt.pix_mp.field != field;
+
+    if (V4L2_TYPE_IS_OUTPUT (v4l2object->type)) {
+      if (is_mplane) {
+        format_changed = format_changed ||
+            format.fmt.pix_mp.colorspace != colorspace;
+      } else {
+        format_changed = format_changed ||
+            format.fmt.pix.colorspace != colorspace;
+      }
+    }
   }
 
 #ifndef GST_DISABLE_GST_DEBUG
@@ -2689,14 +2722,25 @@ gst_v4l2_object_set_format (GstV4l2Object * v4l2object, GstCaps * caps)
   }
 #endif
 
+  if (V4L2_TYPE_IS_OUTPUT (v4l2object->type)) {
+    if (is_mplane)
+      format.fmt.pix_mp.colorspace = colorspace;
+    else
+      format.fmt.pix.colorspace = colorspace;
+
+    GST_DEBUG_OBJECT (v4l2object->element, "Desired colorspace is %d",
+        colorspace);
+  }
+
   if (v4l2_ioctl (fd, VIDIOC_S_FMT, &format) < 0)
     goto set_fmt_failed;
 
   GST_DEBUG_OBJECT (v4l2object->element, "Got format of %dx%d, format "
-      "%" GST_FOURCC_FORMAT ", nb planes %d", format.fmt.pix.width,
-      format.fmt.pix_mp.height,
+      "%" GST_FOURCC_FORMAT ", nb planes %d, colorspace %d",
+      format.fmt.pix.width, format.fmt.pix_mp.height,
       GST_FOURCC_ARGS (format.fmt.pix.pixelformat),
-      is_mplane ? format.fmt.pix_mp.num_planes : 1);
+      is_mplane ? format.fmt.pix_mp.num_planes : 1,
+      is_mplane ? format.fmt.pix_mp.colorspace : format.fmt.pix.colorspace);
 
 #ifndef GST_DISABLE_GST_DEBUG
   if (is_mplane) {