+ if (!ac->tags_mapped && elem_type == TYPE_CPE && ac->m4ac.chan_config==1) {
+ enum ChannelPosition new_che_pos[4][MAX_ELEM_ID]= {0};
+ ac->m4ac.chan_config=2;
+
+ if (set_default_channel_config(ac->avctx, new_che_pos, 2)<0)
+ return -1;
+ if (output_configure(ac, ac->che_pos, new_che_pos, 2, OC_TRIAL_FRAME)<0)
+ return -1;
+ }