videoscale: Fix the src video info error in transfer_colorimetry_from_input()

Pipeline such as:
gst-launch-1.0 -vf videotestsrc ! video/x-raw,format=NV12,colorimetry=\(string\)bt709 \
 ! videoscale ! video/x-raw,format=I420 ! fakesink
Always trigger a error:
ERROR             video-info video-info.c:556:gst_video_info_from_caps: no width property given

Because it is called before the fixate_size(), the src caps' resolution
may be absent or not fixed. That causes that the src video info can not
be created correctly and we can not inherit the colorimetry and chroma-site
from the input caps.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/2289>

diff --git a/subprojects/gst-plugins-base/gst/videoconvertscale/gstvideoconvertscale.c b/subprojects/gst-plugins-base/gst/videoconvertscale/gstvideoconvertscale.c
index 577a03c..fabc63c 100644 (file)
--- a/subprojects/gst-plugins-base/gst/videoconvertscale/gstvideoconvertscale.c
+++ b/subprojects/gst-plugins-base/gst/videoconvertscale/gstvideoconvertscale.c
@@ -795,9 +795,9 @@ gst_video_convert_scale_set_info (GstVideoFilter * filter, GstCaps * in,
   tmp_info = *in_info;
   tmp_info.colorimetry.transfer = out_info->colorimetry.transfer;
   if (gst_video_info_is_equal (&tmp_info, out_info)) {
-    if (gst_video_transfer_function_is_equivalent (in_info->
-            colorimetry.transfer, in_info->finfo->bits,
-            out_info->colorimetry.transfer, out_info->finfo->bits)) {
+    if (gst_video_transfer_function_is_equivalent (in_info->colorimetry.
+            transfer, in_info->finfo->bits, out_info->colorimetry.transfer,
+            out_info->finfo->bits)) {
       gst_base_transform_set_passthrough (GST_BASE_TRANSFORM (filter), TRUE);
     }
   } else {
@@ -1164,17 +1164,34 @@ transfer_colorimetry_from_input (GstBaseTransform * trans, GstCaps * in_caps,
     GstVideoInfo in_info, out_info;
     const GValue *in_colorimetry =
         gst_structure_get_value (in_caps_s, "colorimetry");
+    GstCaps *tmp_caps = NULL;
+    GstStructure *tmp_caps_s;
 
     if (!gst_video_info_from_caps (&in_info, in_caps)) {
       GST_WARNING_OBJECT (trans,
           "Failed to convert sink pad caps to video info");
       return;
     }
-    if (!gst_video_info_from_caps (&out_info, out_caps)) {
+
+    /* We are before fixate_size(), the width and height of
+       the output caps may be absent or not fixed. */
+    tmp_caps = gst_caps_copy (out_caps);
+    tmp_caps = gst_caps_fixate (tmp_caps);
+    tmp_caps_s = gst_caps_get_structure (tmp_caps, 0);
+    if (!gst_structure_has_field (tmp_caps_s, "width"))
+      gst_structure_set_value (tmp_caps_s, "width",
+          gst_structure_get_value (in_caps_s, "width"));
+    if (!gst_structure_has_field (tmp_caps_s, "height"))
+      gst_structure_set_value (tmp_caps_s, "height",
+          gst_structure_get_value (in_caps_s, "height"));
+
+    if (!gst_video_info_from_caps (&out_info, tmp_caps)) {
+      gst_clear_caps (&tmp_caps);
       GST_WARNING_OBJECT (trans,
           "Failed to convert src pad caps to video info");
       return;
     }
+    gst_clear_caps (&tmp_caps);
 
     if (!have_colorimetry && in_colorimetry != NULL) {
       if ((GST_VIDEO_INFO_IS_YUV (&out_info)