Felix Förtsch
4057b692ba
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two simplifications to how we pick and transcode the one-per-language audio track, motivated by seeing inconsistent DTS → FLAC vs DTS → EAC3 outputs in the wild: transcode target: - drop the FLAC path entirely. every incompatible source now targets EAC3 regardless of container or lossless/lossy status - FLAC for movie audio is bad value: ~2-3× the file size vs EAC3, no Atmos spatial metadata (TrueHD Atmos → FLAC silently loses Atmos), no AVR passthrough on Apple TV - one target = no more container-conditional surprises winner within a language group (betterAudio): - new priority: highest channels → Apple-compatible → default → index - old order put 'default' on top which forced a DTS-HD MA transcode even when an AC3 track at equal channels was right next to it. flipping means AC3 beats DTS-HD MA at the same channel count — pure copy instead of a lossless-then-re-encode round trip - channel count still dominates, so 7.1 TrueHD still beats 5.1 AC3 (and gets transcoded, which is the right call for real surround) tests: new case for DTS-HD MA default + AC3 non-default at 5.1 → AC3 wins, job_type=copy. new case for 7.1 TrueHD beats 5.1 AC3 default. every other existing test still holds.
61 lines
2.0 KiB
TypeScript
61 lines
2.0 KiB
TypeScript
// Codec sets and transcode target mapping for Apple device compatibility.
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// Apple natively decodes: AAC, AC3, EAC3, ALAC, FLAC, MP3, PCM, Opus.
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// Everything else (DTS family, TrueHD family, etc.) transcodes to EAC3.
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//
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// Why EAC3 as the single target and not FLAC for lossless sources:
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// - FLAC movie audio is ~2-3× the size of EAC3 at transparent quality
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// - FLAC doesn't preserve Atmos spatial metadata (TrueHD Atmos → FLAC
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// silently drops Atmos); EAC3 JOC can carry it
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// - EAC3 passes through to AVRs over ARC/eARC; FLAC-to-AVR isn't a
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// thing on Apple TV
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// - One target per incompatible source = no container-conditional
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// mapping surprises
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const APPLE_COMPATIBLE_AUDIO = new Set([
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"aac",
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"ac3",
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"eac3",
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"alac",
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"flac",
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"mp3",
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"pcm_s16le",
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"pcm_s24le",
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"pcm_s32le",
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"pcm_f32le",
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"pcm_s16be",
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"pcm_s24be",
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"pcm_s32be",
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"pcm_f64le",
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"opus",
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]);
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export function isAppleCompatible(codec: string): boolean {
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return APPLE_COMPATIBLE_AUDIO.has(codec.toLowerCase());
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}
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/**
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* Maps (codec, profile, container) → target codec for transcoding.
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* Returns null when the source is already Apple-compatible.
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*
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* profile and container are no longer consulted (kept in the signature
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* for call-site stability and potential future per-source tuning).
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*/
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export function transcodeTarget(codec: string, _profile: string | null, _container: string | null): string | null {
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if (isAppleCompatible(codec.toLowerCase())) return null;
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return "eac3";
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}
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/** Determine overall Apple compatibility for a set of kept audio streams. */
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export function computeAppleCompat(
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keptAudioCodecs: string[],
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container: string | null,
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): "direct_play" | "remux" | "audio_transcode" {
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const hasIncompatible = keptAudioCodecs.some((c) => !isAppleCompatible(c));
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if (hasIncompatible) return "audio_transcode";
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const isMkv = !container || container.toLowerCase() === "mkv" || container.toLowerCase() === "matroska";
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if (isMkv) return "remux";
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return "direct_play";
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}
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