Stop Speaking

[esgraham]

Description

As an application user, I'd like to have stop speaking code on the iOS and Android platform, in order to have an event that stops the speaker from speaking.

Acceptance Criteria

• Should have a function in the Cognitive Services plugin that implements the stop speaking functionality for Android.
• Should have a function in the Cognitive Services plugin that implements the stop speaking functionality for iOS.
• README documentation in the plugin should be updated to include changes to the stopSpeak function and example.

[rozele]

FYI - confirmed that the following does not work on Android:

SpeechSynthesizer synthesizer;
...
SpeechConfig config = SpeechConfig.fromSubscription(...);
synthesizer = new SpeechSynthesizer(config);
...
Future<SpeechSynthesisResult> future = synthesizer.SpeakTextAsync(...);
...
future.cancel(true);

[rozele]

Here is an example where I was playing audio from a PullAudioInputStream for Direct Line Speech:

    private void playAudio(PullAudioOutputStream stream, Runnable callback) {
        final int SAMPLE_RATE = 16000;

        final int BUFFER_SIZE = AudioTrack.getMinBufferSize(
                SAMPLE_RATE,
                AudioFormat.CHANNEL_OUT_MONO,
                AudioFormat.ENCODING_PCM_16BIT);

        LinkedList<byte[]> buffer = new LinkedList<>();
        AtomicInteger doneFlag = new AtomicInteger(0);

        AsyncTask.execute(() -> {
            byte[] data = new byte[BUFFER_SIZE];
            while (stream.read(data) > 0) {
                synchronized (buffer) {
                    buffer.add(data);
                }
                data = new byte[BUFFER_SIZE];
            }
            doneFlag.getAndIncrement();
        });

        AsyncTask.execute(() -> {
            AudioTrack audioTrack = new AudioTrack(
                    AudioManager.STREAM_MUSIC,
                    SAMPLE_RATE,
                    AudioFormat.CHANNEL_OUT_MONO,
                    AudioFormat.ENCODING_PCM_16BIT,
                    BUFFER_SIZE,
                    AudioTrack.MODE_STREAM);

            if (audioTrack.getState() == AudioTrack.STATE_INITIALIZED) {
                audioTrack.play();
                byte[] sound = new byte[BUFFER_SIZE];
                while (buffer.size() > 0 || doneFlag.get() == 0) {
                    if (buffer.size() > 0) {
                        audioTrack.write(buffer.peek(), 0, sound.length);
                        synchronized (buffer) {
                            buffer.pop();
                        }
                    }
                }
                audioTrack.stop();
                audioTrack.release();
            }

            if (callback != null) {
                callback.run();
            }
        });
    }

We could add something similar but we'll need to support cancellation.