Google Cloud Speech gRPC API client

Elixir client for Google Cloud Speech-to-Text API using gRPC

Installation

The package can be installed by adding :gcloud_speech_grpc to your list of dependencies in mix.exs:

def deps do
  [
    {:gcloud_speech_grpc, "~> 0.4.0"}
  ]
end

Configuration

This library uses Goth to obtain authentication tokens. It requires Google Cloud credendials to be configured. See Goth's README for details.

Tests with tag :external communicate with Google APIs and require such config, thus are excluded by default, use mix test --include external to run them.

Usage example

alias Google.Cloud.Speech.V1.{
  RecognitionConfig,
  StreamingRecognitionConfig,
  StreamingRecognizeRequest,
  StreamingRecognizeResponse
}

alias GCloud.SpeechAPI.Streaming.Client

cfg =
  RecognitionConfig.new(
    audio_channel_count: 1,
    encoding: :FLAC,
    language_code: "en-GB",
    sample_rate_hertz: 16000
  )

str_cfg =
  StreamingRecognitionConfig.new(
    config: cfg,
    interim_results: false
  )

str_cfg_req =
  StreamingRecognizeRequest.new(
    streaming_request: {:streaming_config, str_cfg}
  )

<<part_a::binary-size(48277), part_b::binary-size(44177),
  part_c::binary>> = File.read!("test/fixtures/sample.flac")

content_reqs =
  [part_a, part_b, part_c] |> Enum.map(fn data ->
    StreamingRecognizeRequest.new(
      streaming_request: {:audio_content, data}
    )
  end)

{:ok, client} = Client.start_link()
client |> Client.send_request(str_cfg_req)

content_reqs |> Enum.each(fn stream_audio_req ->
  Client.send_request(
    client,
    stream_audio_req
  )
end)

Client.end_stream(client)

receive do
  %StreamingRecognizeResponse{results: results} ->
    IO.inspect(results)
end

Auto-generated modules

This library uses protobuf-elixir and its protoc-gen-elixir plugin to generate Elixir modules from *.proto files for Google's Speech gRPC API. The documentation for the types defined in *.proto files can be found here

Mapping between Protobuf types and Elixir modules

Since the auto-generated modules have poor typing and no docs, the mapping may not be obvious. Here are some clues about how to use them:

Structs defined in these modules should be created with new/1 function accepting keyword list with values for fields
when message field is an union field, it should be set to a tuple with atom indicating content of this field and an actual value, e.g. for StreamingRecognizeRequest the field streaming_request can be set to either {:streaming_config, config} or {:audio_content, "binary_with_audio_data"}
Fields of enum types can be set to an integer or an atom matching the enum, e.g. value of field :audio_encoding in RecognitionConfig can be set to :FLAC or 2

Fixture

A recording fragment in test/fixtures comes from an audiobook "The adventures of Sherlock Holmes (version 2)" available on LibriVox

Status

Current version of library supports only Streaming API, regular and LongRunning are not implemented

Copyright and License

Licensed under the Apache License, Version 2.0