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Opened by Tomislav Tustonic@ttustonic

Gst.Object.Replace doesn't seem to work

Hello

I'm trying to create a player, similar to (https://github.com/GStreamer/gst-plugins-base/blob/master/tools/gst-play.c)
In the handler for GST_MESSAGE_STREAM_COLLECTION (line 534) there's a call to gst_object_replace. If I understand correctly, it's supposed to replace an old collection with the new by replacing the pointers.

I try to use Gst.Object.Replace, but it doesn't seem to work and there's an error:
(GstPlayer.exe:19812): GStreamer-CRITICAL **: gst_object_replace: assertion 'oldobj != NULL' failed

When I look at the code for the Replace method it seems that there are a few errors.

  • The gst_object_replace takes a **, so the import should probably be
    static extern bool gst_object_replace(ref IntPtr oldobj, IntPtr newobj); // note the ref oldobj
  • Also, the Replace method should also take a ref Gst.Object oldobj parameter.
  • In the case when the oldptr==null , the IntPtr value sent to the gst_object_replace is not an OwnedHandle of the oldobj, so the oldobj doesn't change.
  • However, since handles in Gst.Object cannot just be replaced, when gst_object_replace returns true, a new value for the oldobj needs to be created with the replaced handle.

Attached are the test and the patch. There are two versions of Replace, a generic and non-generic. Test shows the usage for both of them.

Hope it's OK, Tom

TestStreamCollection.cs 0001-A-fix-for-a-Gst.Object.Replace-in-Object.cs.patch