v4l2: get_nearest_size: Always reinit all struct fields on retry

They may have been modified by the ioctl even if it failed. This also makes
the S_FMT fallback path try progressive first, making it consistent with the
preferred TRY_FMT path.

https://bugzilla.gnome.org/show_bug.cgi?id=735660

diff --git a/sys/v4l2/gstv4l2object.c b/sys/v4l2/gstv4l2object.c
index 1803133..fce97c1 100644 (file)
--- a/sys/v4l2/gstv4l2object.c
+++ b/sys/v4l2/gstv4l2object.c
@@ -2171,6 +2171,8 @@ gst_v4l2_object_get_nearest_size (GstV4l2Object * v4l2object,
   r = v4l2_ioctl (fd, VIDIOC_TRY_FMT, &fmt);
   if (r < 0 && errno == EINVAL) {
     /* try again with interlaced video */
+    memset (&fmt, 0, sizeof (fmt));
+    fmt.type = v4l2object->type;
     fmt.fmt.pix.width = *width;
     fmt.fmt.pix.height = *height;
     fmt.fmt.pix.pixelformat = pixelformat;
@@ -2192,16 +2194,22 @@ gst_v4l2_object_get_nearest_size (GstV4l2Object * v4l2object,
     GST_LOG_OBJECT (v4l2object->element,
         "Failed to probe size limit with VIDIOC_TRY_FMT, trying VIDIOC_S_FMT");
 
+    memset (&fmt, 0, sizeof (fmt));
+    fmt.type = v4l2object->type;
     fmt.fmt.pix.width = *width;
     fmt.fmt.pix.height = *height;
+    fmt.fmt.pix.pixelformat = pixelformat;
+    fmt.fmt.pix.field = V4L2_FIELD_NONE;
 
     r = v4l2_ioctl (fd, VIDIOC_S_FMT, &fmt);
     if (r < 0 && errno == EINVAL) {
-      /* try again with progressive video */
+      /* try again with interlaced video */
+      memset (&fmt, 0, sizeof (fmt));
+      fmt.type = v4l2object->type;
       fmt.fmt.pix.width = *width;
       fmt.fmt.pix.height = *height;
       fmt.fmt.pix.pixelformat = pixelformat;
-      fmt.fmt.pix.field = V4L2_FIELD_NONE;
+      fmt.fmt.pix.field = V4L2_FIELD_INTERLACED;
       r = v4l2_ioctl (fd, VIDIOC_S_FMT, &fmt);
     }