Lesson 234: Audacity Micro-Trailer Stereo Embed Receipt on BUILD_RECEIPT (2026)

Direct answer: Before spring fest store trailer upload, file micro_trailer_stereo_receipt_v1.json proving the Audacity master WAV is stereo (ffprobe channels=2), LUFS in team band, and WebM mux used that master—then run child store_embed_mute_smoke_receipt_v1 on the live embed and promote BUILD_RECEIPT micro_trailer_stereo. Distinct from Lesson 210 GIF marketing (silent carousel copy) and embed mute help (live player triage).

Why this matters now (May 2027 store embed mute desync)

May 2027 teams pass Spline landing LCP and upload a micro-trailer WebM—visitors unmute once, hear nothing, blame Steam. Root cause is often mono-downmixed Audacity export or old silent WebM while a new WAV passed LUFS. The Audacity stereo spot-check preflight is the ninety-second export gate—this lesson wires micro_trailer_stereo_receipt + store_embed_mute_smoke on BUILD_RECEIPT with CI gate verify_micro_trailer_stereo_v1.

Beginner path (master → mux → embed smoke)

Time: ~66 minutes first fest trailer; ~20 minutes when export Macro is pinned.

Developer path (gates S1–S6)

S1–S2 — Export + ffprobe (pre-mux)

Audacity: File → Export → WAV, 48000 Hz, Stereo, 32-bit float.

ffprobe -hide_banner -show_streams -select_streams a:0 deliver/micro_trailer_master.wav

S5 — Mux crosswalk

ffprobe -hide_banner -show_streams -select_streams a:0 deliver/trailer_stereo.webm

Fail when WebM channels=1 but WAV was stereo—re-mux.

micro_trailer_stereo_receipt_v1.json

{
  "schema": "micro_trailer_stereo_receipt_v1",
  "build_label": "spring-fest-2027-rc1",
  "master_wav": "deliver/micro_trailer_master.wav",
  "delivery_webm": "deliver/trailer_stereo.webm",
  "ffprobe_master": {
    "channels": 2,
    "sample_rate": 48000,
    "codec_type": "audio"
  },
  "ffprobe_delivery": {
    "channels": 2,
    "codec_type": "audio"
  },
  "loudness": {
    "integrated_lufs": -14.1,
    "true_peak_dbtp": -1.2,
    "target_band_lufs": [-16, -13],
    "measured_on": "master_wav"
  },
  "child_receipts": {
    "store_embed_mute_smoke": "release-evidence/store-art/STORE_EMBED_MUTE_SMOKE_RECEIPT.json"
  },
  "paired_receipts": {
    "spline_lcp_fest": "release-evidence/03-web/SPLINE_LCP_FEST_RECEIPT.json",
    "carousel_still": "release-evidence/store-art/CAROUSEL_EMBED_STILL_RECEIPT.json"
  },
  "gates": {
    "S1_stereo_export": "pass",
    "S2_ffprobe_master": "pass",
    "S3_lufs_spot": "pass",
    "S4_true_peak": "pass",
    "S5_mux_handoff": "pass",
    "S6_build_receipt": "pass"
  },
  "stereo_master_ok": true,
  "fest_promotion_allowed": false
}

Set fest_promotion_allowed: true only when store_embed_mute_smoke.pass: true.

Pin under release-evidence/audio/MICRO_TRAILER_STEREO_RECEIPT.json.

Child: store_embed_mute_smoke_receipt_v1.json

After live store upload, run embed mute help three-cycle test:

{
  "schema": "store_embed_mute_smoke_receipt_v1",
  "build_label": "spring-fest-2027-rc1",
  "delivery_file": "trailer_stereo.webm",
  "ffprobe_audio_stream_ok": true,
  "channels": 2,
  "three_cycle_audio_ok": true,
  "loudness_receipt_ref": "release-evidence/audio/MICRO_TRAILER_STEREO_RECEIPT.json",
  "pass": true
}

BUILD_RECEIPT rows (S6)

ALTER TABLE release_publish_gate ADD COLUMN IF NOT EXISTS
  micro_trailer_stereo_blocked BOOLEAN NOT NULL DEFAULT false;

Relationship to guide vs help

Key takeaways

1. Mono export is the top cause of “silent after unmute.”
2. ffprobe master before mux—do not trust Audacity UI alone.
3. Child store_embed_mute_smoke is required for fest_promotion_allowed.
4. Lesson 210 — GIF has no audio promise.
5. LUFS listicle picks meters; this lesson picks receipts.
6. Pair carousel still when GIF + WebM ship same week.
7. Q2 capstone 235 wires 234 with 230–233.
8. Wednesday smoke — embed mute photo row.

Common mistakes

• Passing LUFS on WAV, uploading last month’s WebM.
• Measuring loudness on WebM instead of master WAV.
• Skipping three-cycle embed test because “ffprobe was green.”
• Using VO −20 bark preset on full trailer bed.
• Conflating GIF carousel silence with WebM embed failure.

Troubleshooting

Mini exercise (60 minutes)

1. Export mono on purpose—confirm S2 fails.
2. Re-export stereo; pass S1–S5; mux WebM.
3. File parent receipt; run live three-cycle smoke.
4. Attach child JSON; set fest_promotion_allowed: true.
5. BUILD_RECEIPT both rows GREEN.

Continuity — Q2 2027 spring fest shipping (230–235)

Previous: Lesson 233 — Spline embed LCP fest landing
Next: Lesson 235 — Q2 spring fest shipping capstone — Q2 arc 230–235 closed; Course-Planner refill on next go.

FAQ

Same as Audacity stereo preflight guide?
Guide = export gates; 234 = BUILD_RECEIPT + child embed smoke.

Same as embed mute help?
Help = fix live player; 234 = receipt chain before promotion.

Required for GIF carousel?
No—Lesson 210 owns silent GIF copy.

Store embed mute often starts at export—stereo master proof, mux crosswalk, three-cycle smoke, then promote on BUILD_RECEIPT.