Files
lgtv_audio_cap/docs/development.md
T
Rene KievitsandClaude Opus 5 3e4d0e17bc Build the service in a container, and fix what the target compiler found
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>
2026-08-26 10:29:09 +02:00

176 lines
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Markdown

# Building, testing and publishing
## What you need
| For | Install |
| --- | --- |
| the native service | the [openlgtv buildroot NDK](https://github.com/openlgtv/buildroot-nc4/releases) — or Docker, see below |
| packaging | `npm install` (ares-cli), or `npm install -g @webosose/ares-cli` |
| the tests | a host C compiler, Python 3, Node (optional: `flatbuffers`, `jsdom`) |
### The toolchain
The NDK is a **Linux** toolchain — there is no macOS or Windows build of it. On
Linux, unpack and relocate it once:
```sh
tar xf arm-webos-linux-gnueabi_sdk-buildroot-x86_64.tar.gz -C "$HOME"
"$HOME/arm-webos-linux-gnueabi_sdk-buildroot/relocate-sdk.sh"
```
Everywhere else, build the native part in a container:
```sh
./tools/docker-build.sh # -> build/native/audiocap-service
```
That bakes the SDK into an image, so it downloads once and later builds start
immediately. There are aarch64 and x86_64 SDK builds and the image picks
whichever matches the container, so on Apple Silicon it runs natively rather
than under emulation. Only the compile happens in the container; packaging and
deployment run on the host, where the TV is reachable.
Register the TV with ares once, using the Homebrew Channel's ssh (port 9922,
root):
```sh
ares-setup-device --add tv \
--info "{'host':'192.168.1.20','port':9922,'username':'root'}"
```
## Build and deploy
```sh
./tools/build.sh # cross-compile, stage, package -> out/*.ipk
./tools/build.sh install # ares-install on device "tv"
./tools/build.sh launch
./tools/build.sh logs
```
With the container toolchain it is two steps, since `build.sh` only knows how
to drive a local NDK:
```sh
./tools/docker-build.sh && ./tools/build.sh package
```
`DEVICE=livingroom ./tools/build.sh install` targets a different device;
`WEBOS_SDK=/opt/webos-sdk ./tools/build.sh` a differently placed NDK.
The same commands exist as npm scripts (`npm run build`, `npm run deploy`, …)
if that is more your habit. `build.sh` puts `node_modules/.bin` on PATH first,
so a local `npm install` of ares-cli is enough — no global install needed.
### What the packaging step does
`ares-package` takes two directories:
```text
build/stage/app frontend/, minus js/mock.js and its <script> tag
build/stage/service servicefiles/ plus the compiled audiocap-service
```
The service is declared native in `servicefiles/services.json`
(`"engine": "native"`), which is what makes webOS exec the binary rather than
look for a Node entry point.
## Tests
```sh
./test/run-tests.sh
```
Everything runs on the host — no TV involved:
| Suite | What it proves |
| --- | --- |
| syntax check | `service.c` and `main.c` compile against stub Luna/glib headers |
| `verify_flatbuf.py` | the hand-rolled FlatBuffers encoder matches what the official Python runtime decodes — union tags, defaults, vector contents |
| `verify_rtp.py` | the RTP sink and `host/lgtv-audiocap-receiver.py` agree: header layout, sequencing, timestamps, big-endian payload, MTU, and the SDP text |
| `engine_smoke.c` | capture → DSP → fan-out → sockets, including all 44 bytes of the WAV header and the status document |
| `ui_smoke.js` | the real `index.html` loaded in jsdom and driven like a remote |
The two optional dependencies:
```sh
python3 -m venv /tmp/fbvenv && /tmp/fbvenv/bin/pip install flatbuffers
npm install # jsdom
```
Without them those two suites print SKIP and the rest still runs.
To open the UI in a desktop browser — `js/mock.js` stands in for the Luna bus:
```sh
npm run serve # http://localhost:8000
```
## Publishing to the Homebrew Channel
1. Bump `version` in `frontend/appinfo.json`, `servicefiles/package.json` and
`package.json`.
2. `./tools/build.sh` and test the ipk on a real set.
3. Attach the ipk and `frontend/assets/icon.png` to a release.
4. Generate the manifest and attach that too:
```sh
python3 tools/make-manifest.py \
--base-url https://git.crylia.de/Crylia/lgtv_audio_cap/releases/download/v1.0.0
```
5. Submit the manifest URL to [webosbrew/repo](https://github.com/webosbrew/repo).
The manifest sets `"rootRequired": true`, which tells the Homebrew Channel the
service needs elevating. The app can also do it on demand — *System → Grant root
access* runs the Channel's `elevate-service`.
## How the service is put together
```text
main.c registers on the bus, runs the glib loop
service.c the Luna methods and the status subscription
engine.c the capture thread: read a block, analyse it, hand it to every sink
config.c load/merge/atomic-save of config.json
dsp.c peak/RMS envelopes and the 16-band analysis
capture/ one file per backend, all dlopen-based
sinks/ one file per output
net/ RTP, FlatBuffers, the shared stream server
common/ JSON, logging, ring buffer, audio format
```
Three rules hold the design together:
**One format inside.** Everything between a backend and a sink is interleaved
signed 16-bit little-endian PCM at the configured rate. Backends convert on the
way in, sinks convert on the way out. Nothing in the middle branches on sample
type.
**Sinks must never block.** The engine calls every sink from the capture thread,
in order, and a sink that stalls stalls capture. Anything that can wait — a TCP
client that stopped reading, a HyperHDR host that is switched off — buffers
internally and drops the oldest audio instead. The Flatbuffers sink connects
non-blockingly and finishes the handshake on later blocks; sends are bounded to
200 ms.
**Audio libraries are `dlopen`ed, never linked.** A TV without `libpulse` must
still run the ALSA backend, and one with neither must still run the test tone
and start up cleanly. `ldd` on the binary shows glib, luna-service2, libc — no
audio.
### Adding a sink
1. Write `native/src/sinks/sink_yours.c` with an `open` that reads its own key
out of the settings object, plus `write`, `status` and `close`.
2. Define `const sink_driver_t sink_driver_yours` at the bottom and declare it
in `sinks/sink.h`.
3. Add it to the table in `sinks/sink.c` and to `DEFAULTS_JSON` in `config.c`.
4. Add its fields to `SINK_FIELDS` in `frontend/js/app.js`.
The UI needs nothing else: it builds the Outputs panel from `listSinks`.
### Adding a capture backend
The same shape in `native/src/capture/`, with an `available()` that answers
honestly on a TV that lacks the library, and an optional `describe()` that adds
its own fields to the diagnostics.