Rene KievitsandClaude Opus 5
3e4d0e17bc
The openlgtv NDK is a Linux toolchain with no macOS or Windows build, so
tools/build.sh could not produce a binary anywhere else. docker-build.sh
bakes the SDK into an image and compiles there; packaging and deploy stay
on the host, where the TV is reachable. The SDK ships aarch64 as well as
x86_64, so the image picks the one matching the daemon and Apple Silicon
builds natively rather than under emulation.
Cross-compiling for real turned up three things the host compiler did
not:
sink_hyperhdr_viz.c read p->width and p->height to format the error
message after free(p)
sink_hyperhdr.c an SDP connection line of 128 bytes cannot hold
"IN IP4 " plus a 127-byte host plus "/255", so a
long hostname would silently lose its TTL suffix
common/log.c the log body was sized to the whole ring line,
leaving nothing for the prefix; budget for it so
the bound is provable rather than left to
snprintf
A clean cross-compile is now warning-free, and readelf confirms the
design rule holds: luna-service2, glib, PmLogLib and libc, with no
libpulse or libasound.
Also: @webosose/ares-cli was pinned to ^3.0.0, which does not exist
(latest is 2.4.0), so npm install failed outright. build.sh now puts
node_modules/.bin on PATH so a local install is enough.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
125 lines
5.5 KiB
Markdown
125 lines
5.5 KiB
Markdown
# LG TV Audio Cap
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Captures the audio playing on an LG webOS 5 or 6 TV and streams it off the set.
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The reason it exists is HyperHDR: ambient lighting that reacts to what the TV is
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actually playing, without a microphone in the room or an audio splitter behind
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the telly.
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It installs through the [Homebrew Channel](https://github.com/webosbrew/webos-homebrew-channel)
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and runs as a native background service with a remote-friendly UI in front of
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it.
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```
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┌────────────────────── LG webOS TV ──────────────────────┐
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│ PulseAudio / ALSA / a command │
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│ │ │
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│ capture ─► level + 16-band analysis │
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│ │ │
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│ ├─► RTP/L16 ──────────────► HyperHDR host │ ← the main path
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│ ├─► Flatbuffers images ───► HyperHDR │
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│ ├─► raw PCM over UDP │
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│ ├─► raw PCM over TCP │
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│ └─► WAV over HTTP │
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└─────────────────────────────────────────────────────────┘
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```
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## Why it works this way
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HyperHDR has **no network audio input**. Its sound-reactive effects read a
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*local* capture device. So the main path here does not try to talk to HyperHDR
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at all: it sends the TV's audio to the HyperHDR machine as RTP/L16, and a small
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receiver there turns it into a normal sound device that HyperHDR can select.
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That is [`host/lgtv-audiocap-receiver.py`](host/lgtv-audiocap-receiver.py), and
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[`host/install-loopback.sh`](host/install-loopback.sh) sets up the loopback for
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it.
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If you would rather not run anything on the HyperHDR machine, there is a second
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path: the TV does the frequency analysis itself and sends finished images to
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HyperHDR's Flatbuffers port. Fewer moving parts, but the lights react to the
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TV's idea of the spectrum rather than to real audio.
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See [docs/hyperhdr.md](docs/hyperhdr.md) for both, step by step.
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## Requirements
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- An LG TV on webOS 5 or 6, rooted, with the Homebrew Channel installed.
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- Root for the service. The TV's audio devices are not readable otherwise; the
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app has a **Grant root access** button that calls the Homebrew Channel's
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`elevate-service` for you.
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- For the main HyperHDR path: a Linux machine running HyperHDR with either
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`snd-aloop` or PulseAudio/PipeWire available.
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## Installing
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**From the Homebrew Channel.** Open the Homebrew Channel on the TV, find
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*Audio Cap*, install, launch.
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**From an ipk.** Copy the ipk to the TV and install it with the Homebrew
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Channel's *Install from file*, or from a workstation:
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```sh
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ares-install --device tv out/org.webosbrew.audiocap_1.0.0_all.ipk
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```
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**From source.** The NDK is Linux-only, so on macOS or Windows the compile goes
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through Docker:
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```sh
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npm install # ares-cli
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./tools/docker-build.sh # or ./tools/build.sh native on Linux
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./tools/build.sh package # -> out/*.ipk
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```
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See [docs/development.md](docs/development.md) for the rest.
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## First run
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1. Launch **Audio Cap** on the TV.
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2. **System → Root access**: press *Grant root access* if it says the service is
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not root. It restarts itself.
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3. **Capture → Backend**: leave it on *Automatic* to begin with. If nothing is
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captured, run [`tools/tv-probe.sh`](tools/tv-probe.sh) on the TV to see what
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your firmware actually offers, then pick a backend by hand.
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4. **Outputs → HyperHDR audio (RTP/L16)**: turn it on and enter the address of
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the machine running HyperHDR.
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5. On that machine: `sudo ./host/install-loopback.sh --install-service`, then
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point HyperHDR's sound capture at the device it prints.
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6. Press **Start** on the TV. The level meter should move.
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Nothing captured, no idea why? [docs/troubleshooting.md](docs/troubleshooting.md).
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## The other outputs
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Each can run at the same time as the others.
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| Output | What it is | Use it for |
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| --- | --- | --- |
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| **HyperHDR audio** | RTP/L16, port 5004 | the main path; also readable by PulseAudio's `module-rtp-recv` with no custom software |
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| **HyperHDR visualiser** | Flatbuffers images, port 19400 | HyperHDR with nothing installed on the host |
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| **Raw PCM over UDP** | S16LE datagrams, port 4010 | your own scripts; lowest latency |
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| **Raw PCM over TCP** | S16LE stream, port 4011 | anything that would rather connect than listen |
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| **HTTP WAV** | `http://tv:4012/audio.wav` | opening the TV's audio in VLC |
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## Layout
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```
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native/ the webOS service: capture, DSP, sinks, Luna API (C)
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frontend/ the on-TV app (plain HTML/CSS/JS, no framework)
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servicefiles/ services.json, package.json and the boot script
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host/ the receiver and loopback setup for the HyperHDR machine
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tools/ build, packaging, asset generation, on-TV probe
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test/ host-side tests: wire formats, the capture pipeline, the UI
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docs/ the longer explanations
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```
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## Documentation
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- [docs/hyperhdr.md](docs/hyperhdr.md) — connecting it to HyperHDR, both ways
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- [docs/configuration.md](docs/configuration.md) — every setting, and the Luna API
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- [docs/development.md](docs/development.md) — building, testing, packaging, publishing
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- [docs/troubleshooting.md](docs/troubleshooting.md) — when it does not work
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## License
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MIT.
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