// Copyright 2019 Google LLC.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//

syntax = "proto3";

package google.cloud.texttospeech.v1;

import "google/api/annotations.proto";
import "google/api/client.proto";
import "google/api/field_behavior.proto";

option cc_enable_arenas = true;
option csharp_namespace = "Google.Cloud.TextToSpeech.V1";
option go_package = "google.golang.org/genproto/googleapis/cloud/texttospeech/v1;texttospeech";
option java_multiple_files = true;
option java_outer_classname = "TextToSpeechProto";
option java_package = "com.google.cloud.texttospeech.v1";
option php_namespace = "Google\\Cloud\\TextToSpeech\\V1";
option ruby_package = "Google::Cloud::TextToSpeech::V1";

// Service that implements Google Cloud Text-to-Speech API.
service TextToSpeech {
  option (google.api.default_host) = "texttospeech.googleapis.com";
  option (google.api.oauth_scopes) = "https://www.googleapis.com/auth/cloud-platform";

  // Returns a list of Voice supported for synthesis.
  rpc ListVoices(ListVoicesRequest) returns (ListVoicesResponse) {
    option (google.api.http) = {
      get: "/v1/voices"
    };
    option (google.api.method_signature) = "language_code";
  }

  // Synthesizes speech synchronously: receive results after all text input
  // has been processed.
  rpc SynthesizeSpeech(SynthesizeSpeechRequest) returns (SynthesizeSpeechResponse) {
    option (google.api.http) = {
      post: "/v1/text:synthesize"
      body: "*"
    };
    option (google.api.method_signature) = "input,voice,audio_config";
  }
}

// The top-level message sent by the client for the `ListVoices` method.
message ListVoicesRequest {
  // Optional. Recommended.
  // [BCP-47](https://www.rfc-editor.org/rfc/bcp/bcp47.txt) language tag. If
  // specified, the ListVoices call will only return voices that can be used to
  // synthesize this language_code. E.g. when specifying "en-NZ", you will get
  // supported "en-*" voices; when specifying "no", you will get supported
  // "no-*" (Norwegian) and "nb-*" (Norwegian Bokmal) voices; specifying "zh"
  // will also get supported "cmn-*" voices; specifying "zh-hk" will also get
  // supported "yue-*" voices.
  string language_code = 1 [(google.api.field_behavior) = OPTIONAL];
}

// Gender of the voice as described in
// [SSML voice element](https://www.w3.org/TR/speech-synthesis11/#edef_voice).
enum SsmlVoiceGender {
  // An unspecified gender.
  // In VoiceSelectionParams, this means that the client doesn't care which
  // gender the selected voice will have. In the Voice field of
  // ListVoicesResponse, this may mean that the voice doesn't fit any of the
  // other categories in this enum, or that the gender of the voice isn't known.
  SSML_VOICE_GENDER_UNSPECIFIED = 0;

  // A male voice.
  MALE = 1;

  // A female voice.
  FEMALE = 2;

  // A gender-neutral voice.
  NEUTRAL = 3;
}

// Configuration to set up audio encoder. The encoding determines the output
// audio format that we'd like.
enum AudioEncoding {
  // Not specified. Will return result [google.rpc.Code.INVALID_ARGUMENT][].
  AUDIO_ENCODING_UNSPECIFIED = 0;

  // Uncompressed 16-bit signed little-endian samples (Linear PCM).
  // Audio content returned as LINEAR16 also contains a WAV header.
  LINEAR16 = 1;

  // MP3 audio at 32kbps.
  MP3 = 2;

  // Opus encoded audio wrapped in an ogg container. The result will be a
  // file which can be played natively on Android, and in browsers (at least
  // Chrome and Firefox). The quality of the encoding is considerably higher
  // than MP3 while using approximately the same bitrate.
  OGG_OPUS = 3;
}

// The message returned to the client by the `ListVoices` method.
message ListVoicesResponse {
  // The list of voices.
  repeated Voice voices = 1;
}

// Description of a voice supported by the TTS service.
message Voice {
  // The languages that this voice supports, expressed as
  // [BCP-47](https://www.rfc-editor.org/rfc/bcp/bcp47.txt) language tags (e.g.
  // "en-US", "es-419", "cmn-tw").
  repeated string language_codes = 1;

  // The name of this voice.  Each distinct voice has a unique name.
  string name = 2;

  // The gender of this voice.
  SsmlVoiceGender ssml_gender = 3;

  // The natural sample rate (in hertz) for this voice.
  int32 natural_sample_rate_hertz = 4;
}

// The top-level message sent by the client for the `SynthesizeSpeech` method.
message SynthesizeSpeechRequest {
  // Required. The Synthesizer requires either plain text or SSML as input.
  SynthesisInput input = 1 [(google.api.field_behavior) = REQUIRED];

  // Required. The desired voice of the synthesized audio.
  VoiceSelectionParams voice = 2 [(google.api.field_behavior) = REQUIRED];

  // Required. The configuration of the synthesized audio.
  AudioConfig audio_config = 3 [(google.api.field_behavior) = REQUIRED];
}

// Contains text input to be synthesized. Either `text` or `ssml` must be
// supplied. Supplying both or neither returns
// [google.rpc.Code.INVALID_ARGUMENT][]. The input size is limited to 5000
// characters.
message SynthesisInput {
  // The input source, which is either plain text or SSML.
  oneof input_source {
    // The raw text to be synthesized.
    string text = 1;

    // The SSML document to be synthesized. The SSML document must be valid
    // and well-formed. Otherwise the RPC will fail and return
    // [google.rpc.Code.INVALID_ARGUMENT][]. For more information, see
    // [SSML](/speech/text-to-speech/docs/ssml).
    string ssml = 2;
  }
}

// Description of which voice to use for a synthesis request.
message VoiceSelectionParams {
  // Required. The language (and potentially also the region) of the voice expressed as a
  // [BCP-47](https://www.rfc-editor.org/rfc/bcp/bcp47.txt) language tag, e.g.
  // "en-US". This should not include a script tag (e.g. use
  // "cmn-cn" rather than "cmn-Hant-cn"), because the script will be inferred
  // from the input provided in the SynthesisInput.  The TTS service
  // will use this parameter to help choose an appropriate voice.  Note that
  // the TTS service may choose a voice with a slightly different language code
  // than the one selected; it may substitute a different region
  // (e.g. using en-US rather than en-CA if there isn't a Canadian voice
  // available), or even a different language, e.g. using "nb" (Norwegian
  // Bokmal) instead of "no" (Norwegian)".
  string language_code = 1 [(google.api.field_behavior) = REQUIRED];

  // The name of the voice. If not set, the service will choose a
  // voice based on the other parameters such as language_code and gender.
  string name = 2;

  // The preferred gender of the voice. If not set, the service will
  // choose a voice based on the other parameters such as language_code and
  // name. Note that this is only a preference, not requirement; if a
  // voice of the appropriate gender is not available, the synthesizer should
  // substitute a voice with a different gender rather than failing the request.
  SsmlVoiceGender ssml_gender = 3;
}

// Description of audio data to be synthesized.
message AudioConfig {
  // Required. The format of the audio byte stream.
  AudioEncoding audio_encoding = 1 [(google.api.field_behavior) = REQUIRED];

  // Optional. Input only. Speaking rate/speed, in the range [0.25, 4.0]. 1.0 is
  // the normal native speed supported by the specific voice. 2.0 is twice as
  // fast, and 0.5 is half as fast. If unset(0.0), defaults to the native 1.0
  // speed. Any other values < 0.25 or > 4.0 will return an error.
  double speaking_rate = 2 [
    (google.api.field_behavior) = INPUT_ONLY,
    (google.api.field_behavior) = OPTIONAL
  ];

  // Optional. Input only. Speaking pitch, in the range [-20.0, 20.0]. 20 means
  // increase 20 semitones from the original pitch. -20 means decrease 20
  // semitones from the original pitch.
  double pitch = 3 [
    (google.api.field_behavior) = INPUT_ONLY,
    (google.api.field_behavior) = OPTIONAL
  ];

  // Optional. Input only. Volume gain (in dB) of the normal native volume
  // supported by the specific voice, in the range [-96.0, 16.0]. If unset, or
  // set to a value of 0.0 (dB), will play at normal native signal amplitude. A
  // value of -6.0 (dB) will play at approximately half the amplitude of the
  // normal native signal amplitude. A value of +6.0 (dB) will play at
  // approximately twice the amplitude of the normal native signal amplitude.
  // Strongly recommend not to exceed +10 (dB) as there's usually no effective
  // increase in loudness for any value greater than that.
  double volume_gain_db = 4 [
    (google.api.field_behavior) = INPUT_ONLY,
    (google.api.field_behavior) = OPTIONAL
  ];

  // Optional. The synthesis sample rate (in hertz) for this audio. When this is
  // specified in SynthesizeSpeechRequest, if this is different from the voice's
  // natural sample rate, then the synthesizer will honor this request by
  // converting to the desired sample rate (which might result in worse audio
  // quality), unless the specified sample rate is not supported for the
  // encoding chosen, in which case it will fail the request and return
  // [google.rpc.Code.INVALID_ARGUMENT][].
  int32 sample_rate_hertz = 5 [(google.api.field_behavior) = OPTIONAL];

  // Optional. Input only. An identifier which selects 'audio effects' profiles
  // that are applied on (post synthesized) text to speech. Effects are applied
  // on top of each other in the order they are given. See
  // [audio
  // profiles](https://cloud.google.com/text-to-speech/docs/audio-profiles) for
  // current supported profile ids.
  repeated string effects_profile_id = 6 [
    (google.api.field_behavior) = INPUT_ONLY,
    (google.api.field_behavior) = OPTIONAL
  ];
}

// The message returned to the client by the `SynthesizeSpeech` method.
message SynthesizeSpeechResponse {
  // The audio data bytes encoded as specified in the request, including the
  // header for encodings that are wrapped in containers (e.g. MP3, OGG_OPUS).
  // For LINEAR16 audio, we include the WAV header. Note: as
  // with all bytes fields, protobuffers use a pure binary representation,
  // whereas JSON representations use base64.
  bytes audio_content = 1;
}