Yandex Cloud .NET API

This is a .NET Standard 2.0 Yandex Cloud API wrapper. There is not much stuff right now, because I only need SpeechKit. Nevertheless, wrapper architecture is versatile and can accomodate all cloud APIs.

Async

All methods are asynchronous.

Authentication

Only full account (someone@yandex.ru) authentication is currently supported. Service account token retrieval is more complicated and I don't have time to implement JWT token management for service accounts at this moment. Will appreciate the help with this.

Authorization works through IAuthorizer interface. Right now there is only one implementation: FullAccountAuthorizer. You use it with OAuth token as per docs: https://cloud.yandex.ru/docs/iam/operations/iam-token/create.

var fullAuthorizer = new FullAccountAuthorizer(_configuration["OAuthToken"]);
var speechKit = new SpeechKitApi(_fullAuthorizer, _configuration["FolderId"]);

Of course, you don't store your tokens in plain config. You should use .NET Core secrets. For example, read: https://cmatskas.com/configure-and-use-user-secrets-in-net-core-2-0-console-apps-in-development. ApiTest project implements this approach.

Error handling

Expect all meaningful API errors to be wrapped in ApiException. Audio converter errors are wrapped in ConverterException. Treat all other exceptions as unexpected.

SpeechKit

The primary purpose of this wrapper is an ability to recognize and synthesize speech through SpeechKit API. Use SpeechKitApi as your entry point.

For example, to recognize text from speech:

var speechKit = new SpeechKitApi(_fullAuthorizer, _configuration["FolderId"]);
string text = await speechKit.RecognizeTextAsync(data, AudioFormat.PCM);

To synthesize speech from text:

var speechKit = new SpeechKitApi(_fullAuthorizer, _configuration["FolderId"]);
var data = await speechKit.SynthesizeSpeechAsync(
                text, 
                AudioFormat.PCM,
                speed: 0.8f,
                emotion: Emotion.Good);

// In this example *data* will contain raw PCM stream.

Using OPUS format

If you want to recognize a phrase with more than 7-10 words in it, you'll have to use OPUS encoding, as PCM data stream quickly grows over allowed 1 MB file size. OPUS turned out to be a real pain in the butt in .NET, so I ended up using opusec.exe. Saving a temporary wav file to disk and converting it to ogg was the only reliable way to get the stream that SpeechKit doesn't nag at. Using stdin and stdout streams doesn't work reliably. Using https://github.com/lostromb/concentus.oggfile doesn't work. If you find a way to reliably encode OPUS on .NET without opusenc.exe, I welcome your pull request.

OPUS encoding works only on Windows at this moment.

To encode raw PCM stream to OPUS, use AudioConverter. It expects raw PCM stream without WAV header.

var oggData = await new AudioConverter().ConvertPcmToOpusAsync(data, waveIn.WaveFormat);

Testing stuff

You can run ApiTest with different commands to test different things. But first of all, you need to store your OAuth token and folder id to app secret storage.

Fire up the terminal and navigate to ApiTest project folder. Then do:

# dotnet user-secrets set OAuthToken "<your token>"
# dotnet user-secrets set FolderId "<your folder id>"

Now you can build and run the app. To test speech recognition, do:

# ApiTest SpeechRecognition

To test speech synthesis, do:

# ApiTest TextToSpeech

Unit tests

There aren't any at the moment. The code is pretty simple and testing API methods would require a working Cloud account with active payment method. And someone would have to, well, pay for those tests.

aabiryukov/YandexCloudApi