How to check asynchronously Google speech API output stream transcriptions in Ruby?

Question

I am trying to create a Ruby on Rails application that will use a microphone and web sockets to generate real-time speech to text transcription using Google Speech service.

I have successfully sent an audio stream through a web socket to the application, and I am also able to send and receive a transcript from the stream using the streaming_recognize method on an object created using Google::Cloud::Speech.speech. The problem is that I receive the transcript only after the stream has ended.

I tried to use async gem to send audio to input_streamand read output_stream in the Async blocks. The thing is the block which reads an output_stream blocks the entire application even the second block which sends audio chunks to the input_stream.

Here is my code (blocking):

require 'google/cloud/speech'
require 'gapic-common'
require 'async'

audio_file_path = './output.webm'
speech = Google::Cloud::Speech.speech

audio_content = File.binread audio_file_path
bytes_total   = audio_content.size
bytes_sent    = 0
chunk_size    = 32_000

input_stream = Gapic::StreamInput.new
output_stream = speech.streaming_recognize input_stream

config = {
  config: {
    encoding:                 :WEBM_OPUS,
    sample_rate_hertz:        48_000,
    language_code:            "pl-PL",
    enable_word_time_offsets: true
  }
}
input_stream.push streaming_config: config

Sync do |task|
  # Simulated streaming from a microphone
  task.async do
    # Stream bytes...
    while bytes_sent < bytes_total
      puts "Sending audio chunk"
      input_stream.push audio_content: audio_content[bytes_sent, chunk_size]
      puts "Sent audio chunk"
      bytes_sent += chunk_size
      sleep 1
    end

    puts "Stopped passing"
    input_stream.close
  end

  task.async do
    loop do
      puts "Checking output stream if any to read?"
      puts output_stream.any? # If you comment out this line everything runs smoothly again
      puts "Output stream checked"
      sleep 1
    end
  end
end