I might be the only one, but I absolutely don't understand what this is about from the information in this report and the summary.

Then read the GstMeta docs ;)

GstMetaInfo has a transform_func, which is called to transform the meta on a buffer in various situations. We have those for "copy" and "scale" at least currently. See the implementation for "scale" in the ROI or crop meta for example to get an idea how this stuff works.

Having the same for cropping would probably be a good idea.

Created attachment 309941 [details] [review]
proof of concept: crop meta transform type

I'm not sure if it's correct, but I suggested this as a proof of concept.
I referred to the videocrop element.

Additionally, I'm wondering whether dimension is required.

Review of attachment 309941 [details] [review]:

To be useful, we need an implementation for all registered video meta. Also to prove it can works. ROI should be trivial, I think GstVideoOverlayCompositionMeta is the most important here. As videocrop now handle cropping on top of an existing crop, it would be nice proof of concept to also port that element.

::: gst-libs/gst/video/gstvideometa.c
@@ +488,3 @@
 
+/**
+ * gst_video_meta_transform_scale_get_quark:

transform_crop_get_quark

@@ +490,3 @@
+ * gst_video_meta_transform_scale_get_quark:
+ *
+ * Get the #GQuark for the "gst-video-scale" metadata transform operation.

Typo "gst-video-crop"

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