ffdtmf

#!/usr/bin/env bash

# ffdtmf: Generate a sequence of DTMF tones corresponding to the given number.

set -eo pipefail

# Feel free to override these; DUR controls tone duration, GAP is gap between tones.
DUR="${DUR:-0.225}"
GAP="${GAP:-0.15}"

declare -A tone_map
tone_map=(
  ['1']="697 1209"
  ['2']="697 1336"
  ['3']="697 1477"
  ['A']="697 1633"
  ['4']="770 1209"
  ['5']="770 1336"
  ['6']="770 1477"
  ['B']="770 1633"
  ['7']="852 1209"
  ['8']="852 1336"
  ['9']="852 1477"
  ['C']="852 1633"
  ['*']="941 1209"
  ['0']="941 1336"
  ['#']="941 1477"
  ['D']="941 1633"
)

# Cache our generated DTMFs, so that we don't have to rebuild
# them on every duplicated number.
declare -A tone_cache

function help {
  echo "Usage: ffdtmf <number> <output>"
  exit
}

function installed {
  cmd=$(command -v "${1}")

  [[ -n "${cmd}" ]] && [[ -f "${cmd}" ]]
  return ${?}
}

function cleanup {
  rm -f "${tonea}"
  rm -f "${toneb}"
  rm -f "${quiet}"
  rm -f "${tone_cache[@]}"
  rm -f "${concat}"
}

trap cleanup EXIT

tonea=$(mktemp -u ffdialtone-tonea-XXXXX.wav)
toneb=$(mktemp -u ffdialtone-toneb-XXXXX.wav)
quiet=$(mktemp -u ffdialtone-quiet-XXXXX.wav)
comps=()

[[ $# -eq 2 && ! -f $2 ]] || help
[[ $1 =~ [0-9A-D#*]+ ]] || help
installed ffmpeg || { >&2 echo "Missing ffmpeg."; exit 1; }

ffmpeg -f lavfi -i anullsrc -t "${GAP}" "${quiet}"

for (( i = 0; i < "${#1}"; i++ )); do
  digit="${1:${i}:1}"
  freqs=(${tone_map["${digit}"]})

  if [[ -z "${tone_cache[${digit}]}" ]]; then
    ffmpeg -y -f lavfi -i "sine=frequency=${freqs[0]}:duration=${DUR}" -af "volume=-13dB" "${tonea}"
    ffmpeg -y -f lavfi -i "sine=frequency=${freqs[1]}:duration=${DUR}" -af "volume=-13dB" "${toneb}"
    comp=$(mktemp -u ffdialtone-comp-XXXXX.wav)

    ffmpeg -i "${tonea}" -i "${toneb}" -filter_complex "amix=inputs=2:duration=first" "${comp}"

    tone_cache["${digit}"]="${comp}"
  else
    comp="${tone_cache[${digit}]}"
  fi

  comps+=("${comp}" "${quiet}")
done

concat=$(mktemp -u ffdialtone-concat-XXXXX.txt)

for comp in "${comps[@]}"; do
  echo "file '${comp}'" >> "${concat}"
done

ffmpeg -f concat -i "${concat}" -c copy "${2}"