SpeechSynthesizer 的 SpeakProgressEventArgs 是否不准确？

Question

使用 .Net 3.5 中的 System.Speech.Synthesis.SpeechSynthesizer 类，SpeakProgressEventArgs 的 AudioPosition 属性似乎不准确。

以下代码产生以下输出：

代码：

using System;
using System.Speech.Synthesis;
using System.Threading;

namespace SpeechTest
{
    class Program
    {
        static ManualResetEvent speechDoneEvent = new ManualResetEvent(false);

        static void Main(string[] args)
        {
            SpeechSynthesizer synthesizer = new SpeechSynthesizer();

            synthesizer.SpeakProgress += new EventHandler<SpeakProgressEventArgs>(synthesizer_SpeakProgress);

            synthesizer.SpeakCompleted += new EventHandler<SpeakCompletedEventArgs>(synthesizer_SpeakCompleted);

            synthesizer.SetOutputToWaveFile("Test.wav");

            synthesizer.SpeakAsync("This holiday season, support the music you love by shopping at Made in Washington, online and at one of five local stores. Made in Washington chocolates, bountiful gift baskets and ornaments are the perfect holiday gifts for family, friends and co-workers.");

            speechDoneEvent.WaitOne();
        }

        static void synthesizer_SpeakCompleted(object sender, SpeakCompletedEventArgs e)
        {
            speechDoneEvent.Set();
        }

        static void synthesizer_SpeakProgress(object sender, SpeakProgressEventArgs e)
        {
            Console.WriteLine("SpeakProgress: AudioPosition=" + e.AudioPosition + ",\tCharacterPosition=" + e.CharacterPosition + ",\tCharacterCount=" + e.CharacterCount + ",\tText=" + e.Text);
        }
    }
}

输出：

SpeakProgress: AudioPosition=00:00:00.0043750,  CharacterPosition=0,    CharacterCount=4,       Text=This
SpeakProgress: AudioPosition=00:00:00.2925625,  CharacterPosition=5,    CharacterCount=7,       Text=holiday
SpeakProgress: AudioPosition=00:00:00.9086250,  CharacterPosition=13,   CharacterCount=6,       Text=season
SpeakProgress: AudioPosition=00:00:01.9421250,  CharacterPosition=21,   CharacterCount=7,       Text=support
SpeakProgress: AudioPosition=00:00:02.5621250,  CharacterPosition=29,   CharacterCount=3,       Text=the
SpeakProgress: AudioPosition=00:00:02.6760625,  CharacterPosition=33,   CharacterCount=5,       Text=music
SpeakProgress: AudioPosition=00:00:03.2648125,  CharacterPosition=39,   CharacterCount=3,       Text=you
SpeakProgress: AudioPosition=00:00:03.5199375,  CharacterPosition=43,   CharacterCount=4,       Text=love
SpeakProgress: AudioPosition=00:00:03.8435625,  CharacterPosition=48,   CharacterCount=2,       Text=by
SpeakProgress: AudioPosition=00:00:04.0701875,  CharacterPosition=51,   CharacterCount=8,       Text=shopping
SpeakProgress: AudioPosition=00:00:04.6840625,  CharacterPosition=60,   CharacterCount=2,       Text=at
SpeakProgress: AudioPosition=00:00:04.8036250,  CharacterPosition=63,   CharacterCount=4,       Text=Made
SpeakProgress: AudioPosition=00:00:05.0698125,  CharacterPosition=68,   CharacterCount=2,       Text=in
SpeakProgress: AudioPosition=00:00:05.2521250,  CharacterPosition=71,   CharacterCount=10,      Text=Washington
SpeakProgress: AudioPosition=00:00:06.2961875,  CharacterPosition=83,   CharacterCount=6,       Text=online
SpeakProgress: AudioPosition=00:00:07.0540625,  CharacterPosition=90,   CharacterCount=3,       Text=and
SpeakProgress: AudioPosition=00:00:07.3331250,  CharacterPosition=94,   CharacterCount=2,       Text=at
SpeakProgress: AudioPosition=00:00:07.6818750,  CharacterPosition=97,   CharacterCount=3,       Text=one
SpeakProgress: AudioPosition=00:00:08.0598750,  CharacterPosition=101,  CharacterCount=2,       Text=of
SpeakProgress: AudioPosition=00:00:08.2163750,  CharacterPosition=104,  CharacterCount=4,       Text=five
SpeakProgress: AudioPosition=00:00:08.5971875,  CharacterPosition=109,  CharacterCount=5,       Text=local
SpeakProgress: AudioPosition=00:00:09.0243750,  CharacterPosition=115,  CharacterCount=6,       Text=stores
SpeakProgress: AudioPosition=00:00:10.5325625,  CharacterPosition=123,  CharacterCount=4,       Text=Made
SpeakProgress: AudioPosition=00:00:10.7700625,  CharacterPosition=128,  CharacterCount=2,       Text=in
SpeakProgress: AudioPosition=00:00:10.9377500,  CharacterPosition=131,  CharacterCount=10,      Text=Washington
SpeakProgress: AudioPosition=00:00:11.6708125,  CharacterPosition=142,  CharacterCount=10,      Text=chocolates
SpeakProgress: AudioPosition=00:00:12.9798750,  CharacterPosition=154,  CharacterCount=9,       Text=bountiful
SpeakProgress: AudioPosition=00:00:13.6303125,  CharacterPosition=164,  CharacterCount=4,       Text=gift
SpeakProgress: AudioPosition=00:00:14.0959375,  CharacterPosition=169,  CharacterCount=7,       Text=baskets
SpeakProgress: AudioPosition=00:00:14.7848125,  CharacterPosition=177,  CharacterCount=3,       Text=and
SpeakProgress: AudioPosition=00:00:15.0507500,  CharacterPosition=181,  CharacterCount=9,       Text=ornaments
SpeakProgress: AudioPosition=00:00:15.7195000,  CharacterPosition=191,  CharacterCount=3,       Text=are
SpeakProgress: AudioPosition=00:00:15.9872500,  CharacterPosition=195,  CharacterCount=3,       Text=the
SpeakProgress: AudioPosition=00:00:16.1488750,  CharacterPosition=199,  CharacterCount=7,       Text=perfect
SpeakProgress: AudioPosition=00:00:16.7275000,  CharacterPosition=207,  CharacterCount=7,       Text=holiday
SpeakProgress: AudioPosition=00:00:17.3336875,  CharacterPosition=215,  CharacterCount=5,       Text=gifts
SpeakProgress: AudioPosition=00:00:17.9813125,  CharacterPosition=221,  CharacterCount=3,       Text=for
SpeakProgress: AudioPosition=00:00:18.2216875,  CharacterPosition=225,  CharacterCount=6,       Text=family
SpeakProgress: AudioPosition=00:00:19.0973750,  CharacterPosition=233,  CharacterCount=7,       Text=friends
SpeakProgress: AudioPosition=00:00:19.7726250,  CharacterPosition=241,  CharacterCount=3,       Text=and
SpeakProgress: AudioPosition=00:00:19.9655625,  CharacterPosition=245,  CharacterCount=10,      Text=co-workers
SpeakProgress: AudioPosition=00:00:20.2518750,  CharacterPosition=245,  CharacterCount=10,      Text=co-workers

但是，生成的 .wav 文件的持续时间为 15.69 秒。如果输出到 Stream 或 null，也会发生相同的行为。

该属性的文档表示该属性是“一个 TimeSpan 对象，表示音频输出流中事件的时间位置”。

它应该是一个准确的时间，指示输出文件中单词开始或结束的时间，还是我误解了它？

Answer 1

audioPosition 取决于语音合成器所选的语音。根据我的经验，对于某些 Microsoft 声音，例如 Anna、Zira、David、Hazel，支持的音频格式是 16000Hz PCM。所以下面的解决方案可以纠正auido位置：

var format = 
new System.Speech.AudioFormat.SpeechAudioFormatInfo(EncodingFormat.Pcm, 
                                                    16000, 16, 1, 32000, 2, null);
synthesizer.SetOutputToWaveFile("Test.wav", format);

如果你注意的话，SetOutputToWaveFile的默认采样率为22050，正确时间（15.69）与AudipPosition显示的时间的比率 (20.25) 约为 0.77。如果将此比率乘以 22050，您将得到大约 16000，这是正确的采样率。