AV_DOWNMIX_TYPE_LTRT 1603 libavcodec/ac3dec.c             downmix_info->preferred_downmix_type = AV_DOWNMIX_TYPE_LTRT;
AV_DOWNMIX_TYPE_LTRT   96 libavfilter/af_ashowinfo.c     case AV_DOWNMIX_TYPE_LTRT:    av_log(ctx, AV_LOG_INFO, "Lt/Rt");              break;