684 lines
26 KiB
Python
684 lines
26 KiB
Python
# Copyright 2026 Umbra Tools (umbratools.com)
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# SPDX-License-Identifier: Apache-2.0
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from __future__ import annotations
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import json
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import logging
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import re
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import subprocess
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from dataclasses import dataclass, field
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from datetime import UTC, datetime
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from pathlib import Path
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from typing import TYPE_CHECKING, Any
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import numpy as np
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import soundfile as sf
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if TYPE_CHECKING:
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from collections.abc import Callable
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logger = logging.getLogger(__name__)
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SAMPLE_RATE = 24000
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TARGET_SAMPLE_RATE = 44100
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BIT_RATE = "192k"
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SILENCE_MS = 2000
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MAX_TRACK_SEC = 119 * 60
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MAX_FILE_BYTES = 170 * 1024 * 1024
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RMS_LO_DB = -23.0
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RMS_HI_DB = -18.0
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PEAK_MAX_DB = -3.0
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NORM_TARGET_RMS_DB = -20.5
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NORM_MAX_GAIN_DB = 12.0
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PEAK_LIMIT_LINEAR = float(10 ** (PEAK_MAX_DB / 20))
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# libmp3lame overshoots the float peak ceiling by roughly 1 dB, so the ENCODED
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# file must be re-measured and, if it still breaches, re-encoded with the excess
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# trimmed. Two passes is normally enough; the cap stops a pathological track
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# from looping forever.
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PEAK_ENFORCE_PASSES = 3
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SAMPLE_MARKER_TEXT = "Welcome to the audio book"
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STORY_START_RE = re.compile(r"\bchapter\s+(one|1)\b", re.IGNORECASE)
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@dataclass
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class ARChapter:
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"""One manuscript chapter and how it participates in the AR package."""
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chapter_id: int
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chapter_index: int
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title: str
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first_utterance: str = ""
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audio_path: Path | None = None
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role: str = "chapter"
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number: str = ""
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@property
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def display_title(self) -> str:
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return (self.title or f"Chapter {self.chapter_id}").strip()
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@dataclass
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class ARTrack:
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seq: int
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role: str
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title: str
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filename: str
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source: str
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duration_s: float
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size_bytes: int
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number: str = ""
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rms_db: float | None = None
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peak_db: float | None = None
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warning: str = ""
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loudness_ok: bool = True
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peak_ok: bool = True
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segments: list[tuple[str, Any]] = field(default_factory=list)
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@property
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def display_title(self) -> str:
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prefix = self.number
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return f"{prefix} {self.title}".strip() if prefix else self.title
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def as_dict(self) -> dict[str, Any]:
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return {
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"seq": self.seq,
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"role": self.role,
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"number": self.number,
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"title": self.display_title,
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"name": self.title,
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"file": self.filename,
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"source": self.source,
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"duration_s": round(self.duration_s, 2),
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"size_bytes": self.size_bytes,
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"rms_db": self.rms_db,
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"peak_db": self.peak_db,
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"warning": self.warning,
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"loudness_ok": self.loudness_ok,
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"peak_ok": self.peak_ok,
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}
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class ARPackageExporter:
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"""Build the Author's Republic MP3 submission package.
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Every track maps 1:1 to a manuscript chapter that the author edits:
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the sample chapter ("Sample Track"), each story chapter, and the final
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chapter ("Closing Track"). No audio is synthesized — all content comes
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from the project's ``chapter_audio`` files. Every file is forced to mono,
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44.1 kHz, 192 kbit CBR MP3 with 2 seconds of silence at both ends. Each
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track is loudness-normalized to a −20.5 dB RMS target with a hard −3 dBFS
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peak ceiling so the package meets AR's loudness gates; a JSON manifest of
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per-track statistics (duration, size, loudness, peak, AR compliance flags)
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is written beside the files.
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"""
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def __init__(self, data_dir: Path, ffmpeg: str = "ffmpeg", ffprobe: str = "ffprobe") -> None:
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self.data_dir = Path(data_dir)
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self.ffmpeg = ffmpeg
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self.ffprobe = ffprobe
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self.package_dir = self.export_dir / "ar_package"
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self.work_dir = self.export_dir / "ar_work"
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@property
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def export_dir(self) -> Path:
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return self.data_dir / "export"
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@property
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def chapter_audio_dir(self) -> Path:
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return self.data_dir / "chapter_audio"
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# ------------------------------------------------------------------
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# Public build entry point
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# ------------------------------------------------------------------
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def build(
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self,
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chapters: list[ARChapter],
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meta: dict[str, str],
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force: bool = False,
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progress_cb: Callable[[int, str], None] | None = None,
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) -> dict[str, Any]:
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"""Assemble the full AR package and return the manifest.
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``chapters`` must be in final book order with roles already assigned.
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``meta`` is the publishing metadata (title, author, narrator,
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publisher, output_name) used for file naming.
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``progress_cb`` (if given) is called with ``(percent, detail)``.
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"""
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self.package_dir.mkdir(parents=True, exist_ok=True)
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self.work_dir.mkdir(parents=True, exist_ok=True)
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def _progress(percent: int, detail: str) -> None:
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if progress_cb is not None:
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progress_cb(percent, detail)
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ordered = [c for c in chapters if c.audio_path is not None]
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self._assign_numbers(ordered)
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roles = {c.role: c for c in ordered}
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base = self._base_name(meta)
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tracks: list[ARTrack] = []
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seq = 0
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# sample, then opening, then the story, and the closing credit LAST.
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# Emitting "closing" in this loop placed the end-of-book credit at
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# position 3, ahead of the story it was meant to conclude.
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for role in ("sample", "opening"):
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special = roles.get(role)
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if special is not None:
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track = self._make_track(
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seq=seq + 1, role=role, number=special.number,
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title=special.display_title,
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segments=[("wav", special.audio_path)],
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source=str(special.audio_path.name),
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)
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tracks.append(track)
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seq += 1
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for ch in ordered:
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if ch.role != "chapter":
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continue
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track = self._make_track(
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seq=seq + 1, role="chapter", number=ch.number,
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title=ch.display_title,
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segments=[("wav", ch.audio_path)],
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source=str(ch.audio_path.name),
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)
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tracks.append(track)
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seq += 1
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closing = roles.get("closing")
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if closing is not None:
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tracks.append(
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self._make_track(
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seq=seq + 1, role="closing", number=closing.number,
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title=closing.display_title,
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segments=[("wav", closing.audio_path)],
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source=str(closing.audio_path.name),
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)
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)
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seq += 1
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filenames = self._filename_plan(base, tracks)
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for i, (track, fname) in enumerate(zip(tracks, filenames, strict=True)):
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track.filename = fname
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out = self.package_dir / fname
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self._encode_track(track, out)
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_progress(
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10 + int((i + 1) / len(tracks) * 90),
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f"Encoding track {i + 1}/{len(tracks)} ({fname})...",
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)
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manifest = self._manifest(meta, base, tracks)
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manifest_path = self.export_dir / "ar_package.json"
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manifest_path.write_text(json.dumps(manifest, indent=2))
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logger.info("AR package built: %s (%d tracks)", self.package_dir, len(tracks))
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_progress(100, f"AR package built: {len(tracks)} tracks")
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return manifest
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# ------------------------------------------------------------------
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# Chapter numbering
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# ------------------------------------------------------------------
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def _assign_numbers(self, chapters: list[ARChapter]) -> None:
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"""Set per-chapter display numbers.
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- sample / unnumbered front matter -> no number
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- opening -> ``i``
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- closing -> ``ii``
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- story chapters -> 01, 02, ... in manuscript order, starting at the
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first chapter that self-announces as ``Chapter one``/``Chapter 1``.
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"""
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story = 0
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started = False
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for ch in chapters:
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if ch.role == "sample":
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ch.number = ""
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elif ch.role == "opening":
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ch.number = "i"
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elif ch.role == "closing":
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ch.number = "ii"
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elif ch.role == "chapter":
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if not started and STORY_START_RE.search(ch.first_utterance or ""):
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started = True
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if started:
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story += 1
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ch.number = str(story)
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else:
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ch.number = ""
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# ------------------------------------------------------------------
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# Text / naming
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# ------------------------------------------------------------------
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def _base_name(self, meta: dict[str, str]) -> str:
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raw = meta.get("output_name") or meta.get("title") or "audiobook"
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stem = Path(raw).stem
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stem = re.sub(r"[^\w\s.-]", "", stem).strip()
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stem = re.sub(r"\s+", "_", stem)
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return stem or "audiobook"
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def _filename_plan(self, base: str, tracks: list[ARTrack]) -> list[str]:
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plan = []
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for track in tracks:
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title = re.sub(r"[^\w\s-]", "", track.title).strip()
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title = re.sub(r"\s+", "_", title) or "Track"
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number = track.number
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prefix = number.zfill(2) if number.isdigit() else number
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part = f"{prefix}_" if prefix else ""
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plan.append(f"{base}_{part}{title}.mp3")
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return plan
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# ------------------------------------------------------------------
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# Track assembly, encoding, measurement
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# ------------------------------------------------------------------
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def _make_track(
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self,
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seq: int,
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role: str,
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title: str,
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segments: list[tuple[str, Any]],
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source: str = "",
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number: str = "",
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) -> ARTrack:
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combined = self._concatenate(segments)
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rms, peak = self._measure_loudness(combined)
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duration_s = len(combined) / SAMPLE_RATE + 2 * SILENCE_MS / 1000
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warning = (
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f"track exceeds 119 minutes ({duration_s / 60:.1f} min)"
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if duration_s > MAX_TRACK_SEC
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else ""
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)
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return ARTrack(
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seq=seq,
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role=role,
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number=number,
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title=title,
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filename="",
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source=source,
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duration_s=duration_s,
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size_bytes=0,
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rms_db=rms,
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peak_db=peak,
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warning=warning,
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segments=segments,
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)
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def _encode_track(self, track: ARTrack, out: Path) -> None:
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content = self._concatenate(track.segments)
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content = self._normalize(content, track.rms_db)
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rms, peak, passes = self._encode_and_enforce_peak(content, out)
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if rms is not None:
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track.rms_db, track.peak_db = rms, peak
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track.warning = self._loudness_warning(rms, peak, track.warning)
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track.loudness_ok = RMS_LO_DB <= rms <= RMS_HI_DB
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track.peak_ok = peak is not None and peak <= PEAK_MAX_DB
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if passes > 1:
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track.warning = "; ".join(
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w for w in (track.warning, f"peak enforced over {passes} encodes") if w
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)
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track.size_bytes = out.stat().st_size
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def encode_chapter_mp3(self, wav_path: Path, out: Path) -> dict[str, Any]:
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"""Encode one chapter WAV into an AR-compliant MP3.
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Mirrors :meth:`_encode_track` exactly (mono, 44.1 kHz, 192 kbit CBR
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MP3, loudness-normalized to the −20.5 dB RMS target with the ±12 dB
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gain limit and −3 dBFS peak ceiling, 2 s silence at both ends) so a
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per-chapter ``Build Chapter`` result and the assembled AR package
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produce identical audio. Returns per-file stats (duration, size,
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loudness, peaks, AR compliance flags) for the caller.
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"""
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self.work_dir.mkdir(parents=True, exist_ok=True)
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content, sr = sf.read(str(wav_path), dtype="float32")
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if content.ndim > 1:
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content = content.mean(axis=1)
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if sr != SAMPLE_RATE:
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content = self._resample_chunk(wav_path, sr)
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content = np.asarray(content, dtype=np.float32)
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src_rms, _ = self._measure_loudness(content)
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content = self._normalize(content, src_rms)
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rms, peak, passes = self._encode_and_enforce_peak(content, out)
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duration_s = round(len(content) / SAMPLE_RATE, 2) + 2 * SILENCE_MS / 1000
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warning = self._loudness_warning(rms, peak)
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bits = [warning] if warning else []
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if duration_s > MAX_TRACK_SEC:
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bits.append(f"{duration_s:.0f}s exceeds {MAX_TRACK_SEC // 60} min")
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if passes > 1:
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bits.append(f"peak enforced over {passes} encodes")
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size_bytes = out.stat().st_size
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if size_bytes > MAX_FILE_BYTES:
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bits.append(f"{size_bytes / (1024 * 1024):.0f} MB exceeds 170 MB")
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return {
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"duration_s": duration_s,
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"size_bytes": size_bytes,
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"rms_db": rms,
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"peak_db": peak,
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"warning": "; ".join(bits),
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"loudness_ok": rms is not None and RMS_LO_DB <= rms <= RMS_HI_DB,
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"peak_ok": peak is not None and peak <= PEAK_MAX_DB,
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}
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def _normalize(self, audio: np.ndarray, source_rms: float | None) -> np.ndarray:
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audio = np.asarray(audio, dtype=np.float32)
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if source_rms is None:
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return audio
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gain_db = min(max(NORM_TARGET_RMS_DB - source_rms, -NORM_MAX_GAIN_DB), NORM_MAX_GAIN_DB)
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scaled = audio * float(10 ** (gain_db / 20))
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np.clip(scaled, -PEAK_LIMIT_LINEAR, PEAK_LIMIT_LINEAR, out=scaled)
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return scaled
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def _measure_file(
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self, path: Path, content_s: float | None = None
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) -> tuple[float | None, float | None]:
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"""Measure RMS and peak of an ENCODED file, not of the source buffer.
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``content_s`` excludes the head/tail room tone from the RMS measurement.
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Every distributor defines RMS over "the entire program (not including
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room tone)", and the padding's share varies enormously: it is worth
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0.03 dB on a 30-minute chapter but ~7 dB on a 1-second one, which is
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what made synthetic fixtures read low. Peak is unaffected either way
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because padding is silence and cannot raise a peak, so the same trimmed
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pass serves both figures.
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The gate must describe the bytes the listener receives. Measuring the
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pre-encode float array certified our intent rather than the artifact:
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libmp3lame overshoots the ceiling, so all 32 tracks passed at exactly
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-3.0 dB while the shipped MP3s sat near -2.0 dB.
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"""
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head_s = SILENCE_MS / 1000.0
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chain = "volumedetect"
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if content_s is not None and content_s > 0:
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chain = f"atrim=start={head_s}:end={head_s + content_s:.4f},volumedetect"
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try:
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result = subprocess.run(
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[self.ffmpeg, "-i", str(path), "-af", chain, "-f", "null", "-"],
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capture_output=True,
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text=True,
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check=True,
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)
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except subprocess.CalledProcessError:
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return None, None
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stderr = result.stderr or ""
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rms = peak = None
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m = re.search(r"mean_volume:\s*([-\d.]+) dB", stderr)
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if m:
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rms = float(m.group(1))
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m = re.search(r"max_volume:\s*([-\d.]+) dB", stderr)
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if m:
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peak = float(m.group(1))
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return rms, peak
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def _encode_and_enforce_peak(
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self, content: np.ndarray, out: Path
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) -> tuple[float | None, float | None, int]:
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"""Encode to ``out``, trimming gain until the FILE meets the peak ceiling.
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Both figures are read from the **encoded MP3 after any trim**, so the
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manifest always describes the delivered bytes.
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Peak must come from the encoded file: libmp3lame overshoots the float
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ceiling, so only the delivered file reveals the breach.
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RMS from the encoded file is still the whole-program measure without
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room tone: the 2 s head and tail padding is 4 s out of hundreds, worth
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under 0.1 dB (measured 0.03 dB). Measuring the padded WAV instead was
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far worse - it read ~9 dB low on a quiet title, because that buffer was
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pre-normalisation and still full of padding.
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Re-measuring after each trim is what makes the gate honest. Measuring
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RMS once up front recorded a PRE-trim value, so a track that needed peak
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correction was reported ~3 dB louder than it is: ch15 took a -2.9 dB
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trim yet the manifest still said -20.6 dB while the file measured
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-23.8 dB, and the gate called it compliant.
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"""
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work = content
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passes = 0
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rms = peak = None
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content_s = len(content) / SAMPLE_RATE
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for attempt in range(PEAK_ENFORCE_PASSES):
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passes = attempt + 1
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wav = self.work_dir / f"enforce_{out.stem}_{attempt}.wav"
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sf.write(str(wav), self._pad_silence(work), SAMPLE_RATE)
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try:
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self._encode_wav(wav, out)
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finally:
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wav.unlink(missing_ok=True)
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rms, peak = self._measure_file(out, content_s=content_s)
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if peak is None or peak <= PEAK_MAX_DB:
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break
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trim_db = PEAK_MAX_DB - peak
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logger.warning(
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"Encoded peak %.2f dB breaches %.1f dB for %s; re-encoding with %.2f dB trim",
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peak, PEAK_MAX_DB, out.name, trim_db,
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)
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work = work * float(10 ** (trim_db / 20))
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return rms, peak, passes
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def _loudness_warning(
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self, rms: float | None, peak: float | None, base: str = ""
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) -> str:
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bits = [base] if base else []
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if rms is not None and not (RMS_LO_DB <= rms <= RMS_HI_DB):
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bits.append(f"RMS {rms:.1f} dB outside [{RMS_LO_DB}, {RMS_HI_DB}] dB")
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if peak is not None and peak > PEAK_MAX_DB:
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bits.append(f"peak {peak:.1f} dB above {PEAK_MAX_DB} dB")
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return "; ".join(bits)
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def _concatenate(self, segments: list[tuple[str, Any]]) -> np.ndarray:
|
||
chunks: list[np.ndarray] = []
|
||
for kind, value in segments:
|
||
if kind == "gap":
|
||
ms = int(value) # type: ignore[arg-type]
|
||
chunks.append(np.zeros(int(SAMPLE_RATE * ms / 1000), dtype=np.float32))
|
||
elif kind == "wav":
|
||
audio, sr = sf.read(str(value), dtype="float32")
|
||
if audio.ndim > 1:
|
||
audio = audio.mean(axis=1)
|
||
if sr != SAMPLE_RATE:
|
||
chunks.append(self._resample_chunk(value, sr))
|
||
else:
|
||
chunks.append(audio.astype(np.float32))
|
||
if not chunks:
|
||
return np.zeros(1, dtype=np.float32)
|
||
return np.concatenate(chunks)
|
||
|
||
def _resample_chunk(self, path: Path, sr: int) -> np.ndarray:
|
||
tmp = self.work_dir / f"resample_{path.stem}_{sr}.wav"
|
||
subprocess.run(
|
||
[self.ffmpeg, "-y", "-i", str(path), "-ar", str(SAMPLE_RATE), str(tmp)],
|
||
capture_output=True,
|
||
check=True,
|
||
)
|
||
audio, _ = sf.read(str(tmp), dtype="float32")
|
||
tmp.unlink(missing_ok=True)
|
||
return audio.astype(np.float32)
|
||
|
||
def _pad_silence(self, audio: np.ndarray) -> np.ndarray:
|
||
pad = np.zeros(int(SAMPLE_RATE * SILENCE_MS / 1000), dtype=np.float32)
|
||
return np.concatenate([pad, audio, pad])
|
||
|
||
def _measure_loudness(self, audio: np.ndarray) -> tuple[float | None, float | None]:
|
||
tmp = self.work_dir / "loudness_probe.wav"
|
||
sf.write(str(tmp), audio, SAMPLE_RATE)
|
||
try:
|
||
result = subprocess.run(
|
||
[self.ffmpeg, "-i", str(tmp), "-af", "volumedetect", "-f", "null", "-"],
|
||
capture_output=True, text=True, check=True,
|
||
)
|
||
except subprocess.CalledProcessError:
|
||
tmp.unlink(missing_ok=True)
|
||
return None, None
|
||
tmp.unlink(missing_ok=True)
|
||
stderr = result.stderr or ""
|
||
rms = peak = None
|
||
m = re.search(r"mean_volume:\s*([-\d.]+) dB", stderr)
|
||
if m:
|
||
rms = float(m.group(1))
|
||
m = re.search(r"max_volume:\s*([-\d.]+) dB", stderr)
|
||
if m:
|
||
peak = float(m.group(1))
|
||
return rms, peak
|
||
|
||
def _encode_wav(self, wav_path: Path, out: Path) -> None:
|
||
result = subprocess.run(
|
||
[
|
||
self.ffmpeg, "-y",
|
||
"-i", str(wav_path),
|
||
"-ar", str(TARGET_SAMPLE_RATE),
|
||
"-ac", "1",
|
||
"-c:a", "libmp3lame",
|
||
"-b:a", BIT_RATE,
|
||
str(out),
|
||
],
|
||
capture_output=True, text=True,
|
||
)
|
||
if result.returncode != 0:
|
||
raise RuntimeError(f"MP3 encoding failed: {result.stderr[-500:]}")
|
||
|
||
# ------------------------------------------------------------------
|
||
# Manifest
|
||
# ------------------------------------------------------------------
|
||
|
||
def _manifest(self, meta: dict[str, str], base: str, tracks: list[ARTrack]) -> dict[str, Any]:
|
||
return {
|
||
"book": {
|
||
"title": meta.get("title", ""),
|
||
"author": meta.get("author", ""),
|
||
"narrator": meta.get("narrator", ""),
|
||
"publisher": meta.get("publisher", ""),
|
||
"output_name": meta.get("output_name", ""),
|
||
},
|
||
"base_name": base,
|
||
"built_at": datetime.now(UTC).isoformat(timespec="seconds"),
|
||
"format": {
|
||
"codec": "mp3",
|
||
"sample_rate": TARGET_SAMPLE_RATE,
|
||
"channels": 1,
|
||
"bit_rate_kbps": 192,
|
||
"cbr": True,
|
||
"silence_s": SILENCE_MS / 1000,
|
||
},
|
||
"track_count": len(tracks),
|
||
"total_duration_s": round(sum(t.duration_s for t in tracks), 2),
|
||
"tracks": [t.as_dict() for t in tracks],
|
||
"warnings": [t.warning for t in tracks if t.warning],
|
||
# Declared, deliberate departures from the spec. A track that is
|
||
# peak-compliant but still under the RMS floor cannot be fixed with
|
||
# gain (it sits exactly at the peak ceiling, so there is no
|
||
# headroom) because its crest factor makes RMS -20.5 and peak -3.0
|
||
# mutually exclusive. Listed here so an exception is a recorded
|
||
# decision rather than something a reviewer has to rediscover from a
|
||
# warning string.
|
||
"accepted_deviations": [
|
||
{
|
||
"track": t.title,
|
||
"file": t.filename,
|
||
"rule": f"RMS floor {RMS_LO_DB} dB",
|
||
"measured_rms_db": t.rms_db,
|
||
"measured_peak_db": t.peak_db,
|
||
"crest_db": (
|
||
round(t.peak_db - t.rms_db, 2)
|
||
if t.rms_db is not None and t.peak_db is not None
|
||
else None
|
||
),
|
||
"reason": (
|
||
"Crest factor makes the RMS window and the peak ceiling "
|
||
"mutually exclusive at this gain. Left as-is: a limiter "
|
||
"would meet the number by squashing transients."
|
||
),
|
||
}
|
||
for t in tracks
|
||
if not t.loudness_ok and t.peak_ok
|
||
],
|
||
}
|
||
|
||
|
||
def discover_chapters(data_dir: Path) -> list[ARChapter]:
|
||
"""Read the project DB + ``chapter_audio`` and assign AR package roles.
|
||
|
||
Role rules (transparent, per-project):
|
||
- **sample**: chapter whose first utterance opens with the book's promo
|
||
intro (``Welcome to the audio book``);
|
||
- **opening**: chapter titled ``Opening Track`` (intro, numbered ``i``);
|
||
- **closing**: the last chapter that has audio (final "Closing Track");
|
||
- **skip**: chapters with no utterances or no audio file — no track kept;
|
||
- **chapter**: everything else, in manuscript order. Display numbers are
|
||
assigned at build time by :meth:`ARPackageExporter._assign_numbers`.
|
||
"""
|
||
import sqlite3
|
||
|
||
db = sqlite3.connect(str(data_dir / "project.db"))
|
||
db.row_factory = sqlite3.Row
|
||
|
||
totals: dict[int, int] = {}
|
||
for r in db.execute("SELECT chapter_id, COUNT(*) AS n FROM utterances GROUP BY chapter_id"):
|
||
totals[r["chapter_id"]] = r["n"]
|
||
|
||
first: dict[int, str] = {}
|
||
for r in db.execute(
|
||
"SELECT chapter_id, utterance_index, text FROM utterances "
|
||
"ORDER BY chapter_id, utterance_index"
|
||
):
|
||
if r["chapter_id"] not in first:
|
||
first[r["chapter_id"]] = (r["text"] or "").strip()
|
||
|
||
rows = db.execute(
|
||
"SELECT id, chapter_index, title FROM chapters ORDER BY chapter_index"
|
||
).fetchall()
|
||
db.close()
|
||
|
||
audio_dir = data_dir / "chapter_audio"
|
||
chapters: list[ARChapter] = []
|
||
for r in rows:
|
||
cid = r["id"]
|
||
if totals.get(cid, 0) == 0:
|
||
continue
|
||
title = (r["title"] or "").strip() or f"Chapter {r['chapter_index']}"
|
||
first_text = first.get(cid, "")
|
||
audio_path = audio_dir / f"ch{cid}_full.wav"
|
||
role = "chapter"
|
||
if first_text.lower().startswith(SAMPLE_MARKER_TEXT.lower()):
|
||
role = "sample"
|
||
elif title.lower().startswith("opening"):
|
||
role = "opening"
|
||
chapters.append(
|
||
ARChapter(
|
||
chapter_id=cid,
|
||
chapter_index=r["chapter_index"],
|
||
title=title,
|
||
first_utterance=first_text,
|
||
audio_path=audio_path if audio_path.exists() else None,
|
||
role=role,
|
||
)
|
||
)
|
||
|
||
last_with_audio = next(
|
||
(c for c in reversed(chapters) if c.audio_path is not None), None
|
||
)
|
||
if last_with_audio is not None:
|
||
last_with_audio.role = "closing"
|
||
return chapters
|
||
|
||
|
||
def export_chapter_mp3(data_dir: Path, wav_path: Path, out: Path) -> dict[str, Any]:
|
||
"""Encode ``wav_path`` into an AR-compliant MP3 at ``out``.
|
||
|
||
Convenience wrapper used by the per-chapter ``Build Chapter`` pipeline and
|
||
the web per-chapter MP3 download so both bake the exact AR normalization
|
||
(44.1 kHz mono, 192 kbit CBR, −20.5 dB RMS target, −3 dBFS peak ceiling,
|
||
2 s edge silence) into every delivered file.
|
||
"""
|
||
return ARPackageExporter(data_dir).encode_chapter_mp3(wav_path, out)
|