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Replace ' — ' with ', ' across 40 files. Hyphens (-) untouched. timecapsule, stefankoelle, LICENSE, CSS comments left as-is.
46 lines
2.1 KiB
Plaintext
46 lines
2.1 KiB
Plaintext
---
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title: "AirPlay Audio"
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section: "smarthome"
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tags: "smarthome"
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parent: "/smarthome/"
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description: "Multi-room AirPlay receivers with software volume boost on Raspberry Pi devices."
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layout: base.njk
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---
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<h1>AirPlay Audio</h1>
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<div class="detail-content">
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<p>Two Raspberry Pis run AirPlay receivers so any Apple device in the flat
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can stream audio to the kitchen or the bathroom without a dedicated
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speaker app.</p>
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<h2>Setup</h2>
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<table>
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<tr><th>Location</th><th>Hardware</th><th>AirPlay version</th><th>Runs as</th></tr>
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<tr><td>Kitchen</td><td>Raspberry Pi 3B</td><td>AirPlay 2</td><td>Docker container (shairport-sync)</td></tr>
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<tr><td>Bathroom</td><td>Raspberry Pi Zero W</td><td>AirPlay 1</td><td>Native systemd service (older OS, legacy repo)</td></tr>
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</table>
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<h2>The volume-boost problem</h2>
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<p>Both Pis' analog audio output is too quiet at full hardware volume, so
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a software mixer stage (<code>+20 dB</code> via an ALSA softvol plugin) sits between
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shairport-sync and the hardware. The hardware mixer itself is deliberately
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left fixed at 100% / 0 dB, and shairport-sync only ever adjusts its own
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internal software volume, this avoids the volume jumps and mixer
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conflicts that show up when multiple layers all try to control loudness.</p>
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<h2>Bathroom-specific integration</h2>
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<p>The bathroom Pi also runs a small custom tool that starts an internet
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radio stream automatically when its light sensor detects the light has
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been switched on. A simple flag file signals whether AirPlay is currently
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active, so the automatic radio stream politely stays off while someone is
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actively AirPlaying, and resumes its normal behavior as soon as the
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AirPlay session ends.</p>
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<h2>Why this design</h2>
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<ul>
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<li>Software-only volume control avoids ALSA mixer conflicts across two different loudness sources.</li>
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<li>The flag-file handoff is trivial to implement and doesn't need a message broker for something this simple.</li>
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<li>Docker on the kitchen Pi keeps that receiver easy to update; the bathroom Pi's older OS made a native install more reliable than fighting Docker on legacy hardware.</li>
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</ul>
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</div>
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