Blazor Server中使用SpeechSynthesizer保存音频且不播放的问题

你当前的代码调用SpeakSsmlAsync时，默认会通过系统音频设备播放合成语音。要实现只保存音频文件、不向用户播放声音的需求，只需在创建SpeechSynthesizer实例时禁用音频输出即可。

核心修改点 #

创建SpeechSynthesizer时，第二个参数传入null（表示不关联任何音频输出设备），替代默认的自动播放配置：

using (var speechSynthesizer = new SpeechSynthesizer(speechConfig, null))

这里的第二个参数是AudioConfig类型，传null会告诉SDK仅生成音频数据，不执行播放操作。

修改后的完整代码 #

using Microsoft.CognitiveServices.Speech;

public class TextToSpeechService : ITextToSpeechService
{
    public async Task SpeakSsmlAndSaveToFile(string text, string filePath)
    {
        var speechConfig = SpeechConfig.FromSubscription("5c4d780b81cb40fca6bd555cc3148765", "westeurope");
        speechConfig.SpeechSynthesisVoiceName = "sk-SK-LukasNeural";

        string ssml = $"<speak version='1.0' xmlns='http://www.w3.org/2001/10/synthesis' xml:lang='en-US'>" +
                      $"<voice name='sk-SK-LukasNeural'>{text}</voice></speak>";
        // 修正路径转义，用正斜杠或双反斜杠避免语法错误
        filePath = "wwwroot/Audio/DictationRecordings/" + filePath;

        // 传入null禁用音频播放，仅生成音频数据
        using (var speechSynthesizer = new SpeechSynthesizer(speechConfig, null))
        {
            var result = await speechSynthesizer.SpeakSsmlAsync(ssml);

            if (result.Reason == ResultReason.SynthesizingAudioCompleted)
            {
                Console.WriteLine($"Speech synthesized for SSML: [{ssml}], and the result is being written to file: {filePath}");

                using (var audioDataStream = AudioDataStream.FromResult(result))
                {
                    await audioDataStream.SaveToWaveFileAsync(filePath);
                }
            }
            else if (result.Reason == ResultReason.Canceled)
            {
                var cancellation = SpeechSynthesisCancellationDetails.FromResult(result);
                Console.WriteLine($"CANCELED: Reason={cancellation.Reason}");
                if (cancellation.Reason == CancellationReason.Error)
                {
                    Console.WriteLine($"CANCELED: ErrorCode={cancellation.ErrorCode}");
                    Console.WriteLine($"CANCELED: ErrorDetails= [{cancellation.ErrorDetails}]");
                    Console.WriteLine($"CANCELED: Did you set the speech resource key and region values?");
                }
            }
        }
    }
}

额外提示 #

• 不要硬编码订阅密钥和区域，建议从Blazor的appsettings.json配置文件中读取，避免密钥泄露。
• 确保wwwroot/Audio/DictationRecordings目录存在，否则保存文件会抛出异常，可在代码中添加目录检查与创建逻辑。

内容的提问来源于stack exchange，提问作者Tomáš Staroň