Speech-To-Text

New in version 27.

Nextcloud offers a Speech-To-Text API. The overall idea is that there is a central OCP API that apps can use to request transcriptions of audio or video files. To be technology agnostic any app can provide this Speech-To-Text functionality by registering a Speech-To-Text provider.

Consuming the Speech-To-Text API

To consume the Speech-To-Text API, you will need \OCP\SpeechToText\ISpeechToTextManager. This manager offers the following methods:

• hasProviders() This method returns a boolean which indicates if any providers have been registered. If this is false you cannot use Speech-To-Text.

• transcribeFile(File $file) This method takes a OCP\Files\File Object which should point to a media file and will attempt to transcribe it in the current process. It will thus block until transcription has finished and will return the transcript as a string. Using this method is thus only recommend in CLI commands or Background Jobs when you are not limited by any HTTP request timeouts and execution time limits.

• scheduleFileTranscription(File $file, ?string $userId, string $appId) This method schedules a transcription of the passed media file in a background job and will thus not block.

Listening to the transcription events

Since scheduleFileTranscription does not block, you will need to listen to the following events in your app to obtain the transcript or be notified of any failure.

• OCP\SpeechToText\Events\TranscriptionSuccessfulEvent This event class offers the getTranscript() method which returns the transcript as a string

• OCP\SpeechToText\Events\TranscriptionFailedEvent This event class offers the getErrorMessage() method which returns the error message as a string (only in English and for debugging purposes, so don’t show this to the user)

Both classes provide the $appId and $userId params that you initially passed to scheduleFileTranscription via getAppId() and getUserId() as well as getFileId() and getFile() to access the media file that was transcribed.

For example, in your lib/AppInfo/Application.php file:

$context->registerEventListener(OCP\SpeechToText\Events\TranscriptionSuccessfulEvent::class, MyTranscriptionListener::class);
$context->registerEventListener(OCP\SpeechToText\Events\TranscriptionFailedEvent::class, MyTranscriptionListener::class);

The corresponding MyReferenceListener class can look like:

<?php
namespace OCA\MyApp\Listener;

use OCA\MyApp\AppInfo\Application;
use OCP\SpeechToText\Events\AbstractTranscriptionEvent;
use OCP\SpeechToText\Events\TranscriptionSuccessfulEvent;
use OCP\SpeechToText\Events\TranscriptionFailedEvent;
use OCP\EventDispatcher\Event;
use OCP\EventDispatcher\IEventListener;

class MyTranscriptionListener implements IEventListener {
    public function handle(Event $event): void {
        if (!$event instanceof AbstractTranscriptionEvent || $event->getAppId() !== Application::APP_ID) {
            return;
        }

        if ($event instanceof TranscriptionSuccessfulEvent) {
            $transcript = $event->getTranscript();
            // store $transcript somewhere
        }

        if ($event instanceof TranscriptionFailedEvent) {
            $error = $event->getErrorMessage();
            $userId = $event->getUserId();
            // Notify relevant user about failure
        }
    }
}

Implementing a Speech-To-Text provider

A Speech-To-Text provider is a class that implements the interface OCP\SpeechToText\ISpeechToTextProvider.

<?php

declare(strict_types=1);

namespace OCA\MyApp\SpeechToText;

use OCA\MyApp\AppInfo\Application;
use OCP\Files\File;
use OCP\SpeechToText\ISpeechToTextProvider;
use OCP\IL10N;

class Provider implements ISpeechToTextProvider {

    public function __construct(
        private IL10N $l,
    ) {
    }

    public function getName(): string {
        return $this->l->t('My awesome speech to text provider');
    }

    public function transcribeFile(File $file): string {
        // transcribe file here and return transcript
    }
}

The method getName returns a string to identify the registered provider in the user interface.

The method transcribeFile transcribes the passed file and returns the transcript. In case transcription fails, you should throw a RuntimeException with an explanatory error message.

The class would typically be saved into a file in lib/SpeechToText of your app but you are free to put it elsewhere as long as it’s loadable by Nextcloud’s dependency injection container.

Provider registration

The provider class is registered via the bootstrap mechanism of the Application class.

<?php

declare(strict_types=1);

namespace OCA\MyApp\AppInfo;

use OCA\MyApp\SpeechToText\Provider;
use OCP\AppFramework\App;
use OCP\AppFramework\Bootstrap\IBootContext;
use OCP\AppFramework\Bootstrap\IBootstrap;
use OCP\AppFramework\Bootstrap\IRegistrationContext;

class Application extends App implements IBootstrap {

    public function register(IRegistrationContext $context): void {
        $context->registerSpeechToTextProvider(Provider::class);
    }

    public function boot(IBootContext $context): void {}

}