ENVY24_PLAY_BUFUNIT
unit = ENVY24_PLAY_BUFUNIT / 4;
bsize = ch->blk * 4 / ENVY24_PLAY_BUFUNIT;
ch->blk *= ENVY24_PLAY_BUFUNIT / 4;
bsize = ch->blk * 4 / ENVY24_PLAY_BUFUNIT;
sc->psize = ENVY24_PLAY_BUFUNIT * ENVY24_SAMPLE_NUM;