Using with Nerves

Nerves cross-compilation is a standard build path for open_jtalk_elixir. The package uses the selected target toolchain and installs runtime files under the dependency's priv/ directory.

Quick start

export MIX_TARGET=rpi4
mix deps.get
mix compile
mix firmware

On the device:

{:ok, info} = OpenJTalk.info()
:ok = OpenJTalk.say("こんにちは")

Target build behavior

When MIX_TARGET is set:

• the native build honors CC, CXX, AR, RANLIB, and STRIP from the target toolchain;
• native outputs are separated by target triplet;
• full static linking is requested by default; and
• the dictionary and voice are bundled by default.

Full static linking depends on libraries supplied by the target toolchain. Set OPENJTALK_FULL_STATIC=0 when dynamic linking is required and the necessary runtime libraries are available in the system.

Audio playback

OpenJTalk.say/2 needs a supported system audio player. Most Nerves images that provide ALSA playback use aplay.

If the system does not include a supported player, generate WAV data with OpenJTalk.to_wav_binary/2 or OpenJTalk.to_wav_file/2 and pass it to the application's audio path.

Firmware size

Approximate uncompressed sizes are:

For size-constrained firmware, disable bundled assets:

MIX_TARGET=rpi4 OPENJTALK_BUNDLE_ASSETS=0 mix deps.compile open_jtalk_elixir

Provision the dictionary and voice separately, for example under /data, then configure their runtime paths:

System.put_env("OPENJTALK_CLI", "/data/open_jtalk/bin/open_jtalk")
System.put_env("OPENJTALK_DICTIONARY_DIR", "/data/open_jtalk/dic")
System.put_env("OPENJTALK_VOICE", "/data/open_jtalk/voices/mei_normal.htsvoice")

OpenJTalk.Assets.reset_cache()

Omit OPENJTALK_CLI when the executable remains bundled with the application.

How assets reach persistent storage is application-specific and outside this library's scope.

Support boundary

CI cross-compiles and inspects an aarch64 RPi 4 executable. New Nerves targets should also be tested on hardware through actual synthesis and playback; a successful cross-build alone does not validate the audio path.

See Building for native build details and the OpenJTalk module documentation for the complete asset-resolution rules.