Piper-TTS as a ROS 2 Service?

[slowrunner]

I have enabled my Raspberry Pi 5 robot to use Piper-TTS in Python programs by calling a shell script to stream the output of Piper-TTS to a wav file and then play the wav file.

python:

        import subprocess
        ...
        cmd = "amixer -D pulse set Master {:d}%".format(80)
        subprocess.check_output(cmd, stderr=subprocess.STDOUT, shell=True)

        cmd = '~/GoPi5Go/plib/piper.sh "%s"' % phrase
        subprocess.check_output(cmd, stderr=subprocess.STDOUT, shell=True)

calling piper.sh:

#!/bin/bash

echo $1 | piper   --model /home/pi/GoPi5Go/models/piper-tts/en_US-arctic-medium.onnx    --output_raw | aplay -D plughw:2,0 -r 22050 -f S16_LE -t raw - 

I have not had any trouble using this technique for straight python programs, but when I attempted to build a ROS 2 Humble "say_node" that offers a /say service - Piper-TTS throws an exception on the second or third call to the service with:

  File "/home/pi/GoPi5Go/ros2ws/build/gopi5go_dave/gopi5go_dave/say_node.py", line 85, in say_cb
    audio = voice.synthesize(text,wav_file)
  File "/usr/local/lib/python3.10/dist-packages/piper/voice.py", line 95, in synthesize
    for audio_bytes in self.synthesize_stream_raw(
  File "/usr/local/lib/python3.10/dist-packages/piper/voice.py", line 123, in synthesize_stream_raw
    yield self.synthesize_ids_to_raw(
  File "/usr/local/lib/python3.10/dist-packages/piper/voice.py", line 166, in synthesize_ids_to_raw
    audio = self.session.run(
  File "/usr/local/lib/python3.10/dist-packages/onnxruntime/capi/onnxruntime_inference_collection.py", line 220, in run
    return self._sess.run(output_names, input_feed, run_options)
onnxruntime.capi.onnxruntime_pybind11_state.RuntimeException: [ONNXRuntimeError] : 6 : RUNTIME_EXCEPTION : Non-zero status code returned while running GatherElements node. Name:'/dp/flows.7/GatherElements_3' Status Message: /onnxruntime_src/onnxruntime/core/providers/cpu/tensor/gather_elements.cc:154 void onnxruntime::core_impl(const Tensor*, const Tensor*, Tensor*, int64_t, concurrency::ThreadPool*) [with Tin = long int; int64_t = long int] GatherElements op: Out of range value in index tensor

[ros2run]: Process exited with failure 1

I should add ROS 2 Humble is running over Ubuntu 22.04 in a Docker container over 64-bit Raspberry Pi OS Bookworm.

Something I need to change to avoid this failure?

Has anyone else built a ROS 2 Humble driver for Piper-TTS?