On each picture the video decoder wrapper did query XDM_GETSTATUS for decoder status,
but error information is alread available in p_sys->out_args in member 'extendedError'.
This patch saves one syscall every picture (except the first). The first picture defines
the output properties of the decoded pictures and these must be stored in p_dec->fmt_out.video.*
to obtain correctly sized pictures (picture_t).