#!/usr/bin/env bash
# Extract audio (16kHz mono wav) from every mp4 in FairTalking-Bench.
# Output mirrors the directory structure under $DATA_ROOT/_audio/.
#
# Usage:
#   export DATA_ROOT=/apdcephfs_gy4/share_303628665/joywu/dataset/FairTalking-Bench
#   bash scripts/prepare_audio.sh                 # default 8 parallel workers
#   bash scripts/prepare_audio.sh 16              # override workers
#
# Requires: ffmpeg, GNU parallel (apt-get install parallel)
set -euo pipefail

: "${DATA_ROOT:?DATA_ROOT must be set}"
WORKERS="${1:-8}"
AUDIO_DIR="$DATA_ROOT/_audio"
mkdir -p "$AUDIO_DIR"

echo "[prepare_audio] DATA_ROOT=$DATA_ROOT  workers=$WORKERS"

extract_one() {
    local mp4="$1"
    local rel="${mp4#$DATA_ROOT/}"
    local out="$AUDIO_DIR/${rel%.mp4}.wav"
    mkdir -p "$(dirname "$out")"
    if [ -f "$out" ]; then return 0; fi
    ffmpeg -y -v error -i "$mp4" -ac 1 -ar 16000 -vn "$out" < /dev/null
}
export -f extract_one
export DATA_ROOT AUDIO_DIR

if command -v parallel >/dev/null 2>&1; then
    find "$DATA_ROOT" -name "*.mp4" ! -path "$AUDIO_DIR/*" \
      | parallel -j "$WORKERS" --bar extract_one {}
else
    echo "[prepare_audio] GNU parallel not found, falling back to xargs -P$WORKERS"
    find "$DATA_ROOT" -name "*.mp4" ! -path "$AUDIO_DIR/*" -print0 \
      | xargs -0 -n1 -P"$WORKERS" -I{} bash -c 'extract_one "$@"' _ {}
fi

echo "[prepare_audio] done. audio root: $AUDIO_DIR"