f_decoder_wrapper: disable non-copy hardware decoding for stream groups

This allows playing tile grid images without manually disabling hardware
decoding. There is no other type of stream group known to support
hardware decoding so far.

Co-authored-by: Guido Cella <guido@guidocella.xyz>

filters/f_decoder_wrapper.c

@@ -1263,6 +1263,10 @@ static bool init_group_decoder(struct priv *p, struct mp_filter *public_f)
         return false;
     }
 
+    mp_require(!public_f->stream_info);
+    struct mp_stream_info *no_hwdec = talloc_zero(public_f, struct mp_stream_info);
+    public_f->stream_info = no_hwdec;
+
     enum mp_frame_type ftype;
     switch (p->header->type) {
     case STREAM_VIDEO: ftype = MP_FRAME_VIDEO; break;