CH_LOW_FREQUENCY  381 libavcodec/avcodec.h #define CH_LAYOUT_5POINT1           (CH_LAYOUT_5POINT0|CH_LOW_FREQUENCY)
CH_LOW_FREQUENCY  383 libavcodec/avcodec.h #define CH_LAYOUT_7POINT1_WIDE      (CH_LAYOUT_SURROUND|CH_LOW_FREQUENCY|\
CH_LOW_FREQUENCY 1243 libavcodec/dca.c             avctx->channel_layout |= CH_LOW_FREQUENCY;