#!/usr/bin/zsh
# script to make sense of compand's parameters
compandy() {
    if [ $# -eq 0 ]; then
        echo -E "usage: $0 {threshold} {ratio} [attack] [release] [knee] [gain] [delay]"
        return 1
    fi
    local thresh="${1:-10}" ratio="${2:-2}"
    local atk="${3:-1}" rel="${4:-100}"
    local knee="${5:-1}" gain="${6:-0}" delay="${7:-0}"
    let 'atk/=1000.'
    let 'rel/=1000.'
    let 'delay/=1000.'
    local end= start=
    let 'end=thresh - thresh/(ratio + 0.0)'
    let 'start=thresh'
    printf "compand=%.5f|%.5f:%.5f|%.5f:%.1f/%.1f|0/%.2f:%.2f:%.2f:%.1f:%.5f" \
      $atk $atk $rel $rel $thresh $thresh $end $knee $gain $start $delay
}
compandy "$@"