[cheese] Preserve video/x-raw over image/jpeg

[David King <davidk src gnome org>]

commit 1c1e7fa0c4608331fd89683ccb342ed3518acccc
Author: Jakub Adam <jakub adam collabora com>
Date:   Tue Sep 3 16:57:00 2019 +0200

    Preserve video/x-raw over image/jpeg
    
    gst_caps_simplify() doesn't preserve the original order of caps, so when
    called on the full set of caps, collected from all supported_formats, it
    may end up preferring image/jpeg caps even when video/x-raw with
    identical resolution and framerate is available.
    
    Simplify the caps coming from each of supported_formats separately, so
    that video/x-raw always comes first in the result GstCaps.
    
    We prefer raw camera output whenever possible in order to avoid decoding
    MJPEG.

 libcheese/cheese-camera-device.c | 38 +++++++++++++++++++++-----------------
 1 file changed, 21 insertions(+), 17 deletions(-)
---
diff --git a/libcheese/cheese-camera-device.c b/libcheese/cheese-camera-device.c
index 34b846a5..efcb0459 100644
--- a/libcheese/cheese-camera-device.c
+++ b/libcheese/cheese-camera-device.c
@@ -893,10 +893,9 @@ cheese_camera_device_get_caps_for_format (CheeseCameraDevice *device,
                                           CheeseVideoFormat  *format)
 {
     CheeseCameraDevicePrivate *priv;
-  CheeseVideoFormatFull *full_format;
-  GstCaps *desired_caps;
-  GstCaps *subset_caps;
-  gsize i;
+    CheeseVideoFormatFull *full_format;
+    GstCaps *result_caps;
+    gsize i;
 
   g_return_val_if_fail (CHEESE_IS_CAMERA_DEVICE (device), NULL);
 
@@ -913,21 +912,26 @@ cheese_camera_device_get_caps_for_format (CheeseCameraDevice *device,
             full_format->width, full_format->height,
             full_format->fr_numerator, full_format->fr_denominator);
 
-  desired_caps = gst_caps_new_empty ();
+    priv = cheese_camera_device_get_instance_private (device);
 
-  for (i = 0; supported_formats[i] != NULL; i++)
-  {
-    gst_caps_append (desired_caps,
-                     cheese_camera_device_format_to_caps (supported_formats[i],
-                                                          full_format));
-  }
+    result_caps = gst_caps_new_empty ();
 
-    priv = cheese_camera_device_get_instance_private (device);
-    subset_caps = gst_caps_intersect (desired_caps, priv->caps);
-  subset_caps = gst_caps_simplify (subset_caps);
-  gst_caps_unref (desired_caps);
+    for (i = 0; supported_formats[i] != NULL; i++)
+    {
+        GstCaps *desired_caps;
+        GstCaps *subset_caps;
+
+        desired_caps = cheese_camera_device_format_to_caps (supported_formats[i],
+                                                            full_format);
+        subset_caps = gst_caps_intersect (desired_caps, priv->caps);
+        subset_caps = gst_caps_simplify (subset_caps);
+
+        gst_caps_append (result_caps, subset_caps);
+
+        gst_caps_unref (desired_caps);
+    }
 
-  GST_INFO ("Got %" GST_PTR_FORMAT, subset_caps);
+    GST_INFO ("Got %" GST_PTR_FORMAT, result_caps);
 
-  return subset_caps;
+    return result_caps;
 }