Speech to text api google Mp3

I want to convert an audio to text, but the audio is in mp3 and it has a duration of one hour I'm doing it asynchronously, what can I do, I have my code in this way:

public class PruebasSpeech {
    public static void main(String... args) throws Exception {  
        asyncRecognizeGcs("gs://cloud_at/2015-077.MP3");
    }

    public static void asyncRecognizeGcs(String gcsUri) throws Exception {


        // Instantiates a client with GOOGLE_APPLICATION_CREDENTIALS
        try (SpeechClient speech = SpeechClient.create()) {

            // Configure remote file request for Linear16
            RecognitionConfig config =
                RecognitionConfig.newBuilder()
                    .setEncoding(AudioEncoding.FLAC)
                    .setLanguageCode("es-CO")
                    .setSampleRateHertz(8000)
                    .build();
            RecognitionAudio audio = RecognitionAudio.newBuilder().setUri(gcsUri).build();

            // Use non-blocking call for getting file transcription
            OperationFuture<LongRunningRecognizeResponse, LongRunningRecognizeMetadata> response =
                speech.longRunningRecognizeAsync(config, audio);
            while (!response.isDone()) {
                System.out.println("Waiting for response...");
                Thread.sleep(10000);
            }

            List<SpeechRecognitionResult> results = response.get().getResultsList();

            for (SpeechRecognitionResult result : results) {
                // There can be several alternative transcripts for a given chunk of speech. Just use the
                // first (most likely) one here.
                SpeechRecognitionAlternative alternative = result.getAlternativesList().get(0);
                System.out.printf("Transcription: %s\n", alternative.getTranscript());
            }
        }
    }
}