#!/bin/bash
# 《暗码》BGM 后处理（批次 3）：Mureka flac 候选 -> 90s 无缝循环 ogg+m4a。
# 用法: bash tools/gen_cipher_bgm_post.sh   （flac 原件在 tools/mureka_out/，不入库）
#
# 工艺（tools/gen_hunt_bgm.sh 同款）：首个强 onset 起点（silenceremove，-35dB 门限）
#   → 93s 裁剪 → 首尾 3s acrossfade(tri) 无缝循环 → loudnorm I=-20/TP=-2/LRA=11
#   → aresample 44.1kHz → ogg libvorbis q3 + m4a aac 128k，落 web/cipher/audio/bgm/。
# cipher 无节拍网格玩法，不跑 bpm_precise（dungeon/hunt 先例）。
set -euo pipefail
cd "$(dirname "$0")/.."
export PATH="$PWD/tools/bin:$PATH"

TMP=tools/bgm_post_wav/cipher
DST=web/cipher/audio/bgm
mkdir -p "$TMP" "$DST"

post() {  # post <flac> <track>
  local src="$1" track="$2"
  local tmp="$TMP/$track.wav"
  ffmpeg -y -v error -i "$src" -af \
"silenceremove=start_periods=1:start_threshold=-35dB:start_silence=0.02,atrim=end=93,asetpts=PTS-STARTPTS,asplit[a][b];[b]atrim=start=90,asetpts=PTS-STARTPTS[t];[a][t]acrossfade=d=3:c1=tri:c2=tri,loudnorm=I=-20:TP=-2:LRA=11,aresample=44100" \
    "$tmp"
  ffmpeg -y -v error -i "$tmp" -c:a libvorbis -q:a 3 "$DST/$track.ogg"
  ffmpeg -y -v error -i "$tmp" -c:a aac -b:a 128k "$DST/$track.m4a"
  echo "$track <- $src"
}

# 选用候选 = 时长更接近 90s 的那支（拿不准原则），详见 tools/mureka_log.md cipher 节
post tools/mureka_out/cipher-radio_room/160722319310849_0.flac  radio_room  # 147.8s
post tools/mureka_out/cipher-closing/160722506153986_0.flac     closing     # 159.5s
post tools/mureka_out/cipher-night/160722722226177_0.flac       night       # 168.6s
post tools/mureka_out/cipher-ending/160722885607425_0.flac      ending      # 163.6s

echo "== cipher bgm done: $(ls "$DST" | wc -l) files =="