scripts(dtmf): added generate_dtmf.sh to generate DTMF wav files

scripts/dtmf/generate_dtmf.sh

@@ -0,0 +1,35 @@
+#!/bin/bash
+
+# DTMF frequency map (low, high)
+declare -A DTMF=(
+  [1]="697 1209"
+  [2]="697 1336"
+  [3]="697 1477"
+  [4]="770 1209"
+  [5]="770 1336"
+  [6]="770 1477"
+  [7]="852 1209"
+  [8]="852 1336"
+  [9]="852 1477"
+  ["star"]="941 1209"
+  [0]="941 1336"
+  ["pound"]="941 1477"
+)
+
+# Tone duration (seconds) + gap after
+DURATION=0.2
+GAP=0.05
+SAMPLERATE=8000
+
+for key in "${!DTMF[@]}"; do
+  freqs=(${DTMF[$key]})
+  low=${freqs[0]}
+  high=${freqs[1]}
+  echo "Generating DTMF tone for $key ($low Hz + $high Hz)"
+  ffmpeg -hide_banner -loglevel error -y \
+    -f lavfi -i "sine=frequency=$low:duration=$DURATION:sample_rate=$SAMPLERATE" \
+    -f lavfi -i "sine=frequency=$high:duration=$DURATION:sample_rate=$SAMPLERATE" \
+    -f lavfi -i "anullsrc=r=$SAMPLERATE:cl=mono:d=$GAP" \
+    -filter_complex "[0][1]amix=2[a];[a][2]concat=n=2:v=0:a=1[out]" \
+    -map "[out]" -c:a pcm_s16le -ar $SAMPLERATE "dtmf-${key}.wav"
+done