Avspeechsynthesizer Output as File

AVSpeechSynthesizer output as file?

As of now AVSpeechSynthesizer does not support this . There in no way get the audio file using AVSpeechSynthesizer . I tried this few weeks ago for one of my apps and found out that it is not possible , Also nothing has changed for AVSpeechSynthesizer in iOS 8.

I too thought of recording the sound as it is being played , but there are so many flaws with that approach like user might be using headphones, the system sound might be low or mute , it might catch other external sound, so its not advisable to go with that approach.

How to store a text-to-speech audio in an audio file (IOS)

The error simply shows An AVSpeechUtterance shall not be enqueued twice .

So stop making it speak and write in the same time .

I used your code and comment out synthesizer.SpeakUtterance(su); , error gone .

Update

Based on my test , it does not allow to create extra subfolder , so remove the TTS/ part , just leave the file name alone .

string filePath = Path.Combine(Path.GetTempPath(),  1 + ".caf");

OBJC AVSpeechUtterance writeUtterance how?

Referring to the potential answer in Swift, this would be the Objective-C implementation

AVSpeechSynthesizer *synthesizer = [[AVSpeechSynthesizer alloc] init];
AVSpeechUtterance *utterance = [[AVSpeechUtterance alloc] initWithString:@"test 123"];
AVSpeechSynthesisVoice *voice = [AVSpeechSynthesisVoice voiceWithLanguage:@"en-US"];
[utterance setVoice:voice];

__block AVAudioFile *output = nil;

[synthesizer writeUtterance:utterance
           toBufferCallback:^(AVAudioBuffer * _Nonnull buffer) {
    AVAudioPCMBuffer *pcmBuffer = (AVAudioPCMBuffer*)buffer;
    if (!pcmBuffer) {
        NSLog(@"Error");
        return;
    }
    if (pcmBuffer.frameLength != 0) {
        //append buffer to file
        if (output == nil) {
            output = [[AVAudioFile alloc] initForWriting:[NSURL fileURLWithPath:@"test.caf"]
                                                settings:pcmBuffer.format.settings
                                            commonFormat:AVAudioPCMFormatInt16
                                             interleaved:NO error:nil];
        }
        [output writeFromBuffer:pcmBuffer error:nil];
    }
}];

Swift: How to Convert Text-to-Speech Generated Audio to .mp3?

2021-02-20 Update:
This is possible now. Please see the thread: AVSpeechSynthesizer output as file?

2017 Answer (outdated):

A simple strategy would be saving your output from AVSpeechSynthesizer to a directory first, then changing its format.

But, as far as I know, AVSpeechSynthesizer does not let you save your outputs.
I would suggest you check the following post: Save audio stream to mp3 file (iOS)

Quoting from IanStallings:

Unfortunately no, there is no public API available to capture the speaker output, and looking over the docs for AVSpeechSynthesizer and related classes I don't see a way to capture any audio from it. You may want to look at 3rd party libraries to help with this.

And another one: AVSpeechSynthesizer output as file?

Again, quoting from Bhumit Mehta:

As of now AVSpeechSynthesizer does not support this. There is no way to get the audio file using AVSpeechSynthesizer. I tried this a few weeks ago for one of my apps and found out that it is not possible, Also nothing has changed for AVSpeechSynthesizer in iOS 8.

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