nerv.speech_utils = {}

function nerv.speech_utils.global_transf(feat_utter, global_transf,
                                        frm_ext, frm_trim, gconf)
    local rearranged
--    feat_utter = gconf.cumat_type.new_from_host(feat_utter)
    if frm_ext ~= nil and frm_ext > 0 then
        local step = frm_ext * 2 + 1
        -- expand the feature
        local expanded = gconf.cumat_type(feat_utter:nrow(), feat_utter:ncol() * step)
        expanded:expand_frm(feat_utter, frm_ext)
        -- rearrange the feature (``transpose'' operation in TNet)
        if gconf.rearrange then
            rearranged = expanded:create()
            rearranged:rearrange_frm(expanded, step)
        else
            rearranged = expanded
        end
    else
        rearranged = feat_utter
    end
    -- prepare for transf
    local input = {rearranged}
    local output = {rearranged:create()}
    -- do transf
    global_transf:init(input[1]:nrow())
    global_transf:propagate(input, output)
    -- trim frames
    expanded = gconf.cumat_type(output[1]:nrow() - frm_trim * 2, output[1]:ncol())
    expanded:copy_fromd(output[1], frm_trim, feat_utter:nrow() - frm_trim)
    collectgarbage("collect")
    return expanded
end