peer_caps = gst_caps_make_writable (peer_caps);
gst_caps_merge (peer_caps, gst_caps_ref (self->converter_caps));
ret = peer_caps;
peer_caps = gst_caps_make_writable (peer_caps);
gst_caps_merge (peer_caps, gst_caps_ref (self->converter_caps));
ret = peer_caps;