使用NAudio转换为WAV后使用SoundPlayer播放MP3

时间:2013-01-29 11:00:46

标签: c# .net naudio

我想使用NET提供的System.Media.SoundPlayer机制播放从网上下载的MP3文件。由于它适用于WAV格式,因此需要例如WAV格式的支持。 NAudio库 - 我需要将MP3转换为WAV。

我想在内存中执行所有操作,因为我需要快速调用它,但我有问题。下面我展示的代码按预期工作,但它与文件合作。相反,我需要让它仅使用内存操作。

(1)有效,但涉及磁盘操作:

public void Speak(Uri mp3FileUri)
{
    using (var client = new WebClient())
    {
        using (var networkStream = client.OpenRead(mp3FileUri))
        {
            if (networkStream != null)
            {
                var temp = Path.GetTempPath();
                var mp3File = Path.Combine(temp, "file.mp3");
                var wavFile = Path.Combine(temp, "file.wav");
                using (var fileStream = File.Create(mp3File))
                {
                    networkStream.CopyTo(fileStream);
                }
                using (var reader = new Mp3FileReader(mp3File))
                {
                    WaveFileWriter.CreateWaveFile(wavFile, reader);
                }                        
                using(var player = new SoundPlayer(wavFile))
                {
                    player.Play();
                }
            }
        }
    }
}

(2)不起作用 - 没有抛出异常,但没有播放:

public void Speak(Uri mp3FileUri)
{
    using (var client = new WebClient())
    {
        using (var networkStream = client.OpenRead(mp3FileUri))
        {
            if (networkStream != null)
            {
                var memStream = new MemoryStream();
                networkStream.CopyTo(memStream);
                memStream.Position = 0;
                using (var reader = new Mp3FileReader(memStream))
                {
                    var outStream = new MemoryStream();
                    using (var writer = new WaveFileWriter(outStream, reader.WaveFormat))
                    {
                        var num = 0L;
                        var buffer = new byte[reader.WaveFormat.AverageBytesPerSecond * 4];
                        while (true)
                        {
                            var count = reader.Read(buffer, 0, buffer.Length);
                            if (count != 0)
                            {
                                num += count;
                                if (num <= int.MaxValue)
                                    writer.Write(buffer, 0, count);
                                else
                                    throw new InvalidOperationException("Too large file or endless stream.");
                            }
                            else
                                break;
                        }
                        writer.Flush();
                        outStream.Position = 0;
                        using(var player = new SoundPlayer(outStream))
                        {
                            player.Play(); /* why silence ? */
                        }
                    }                            
                }
            }
        }
    }
}

如何处理以及第二个代码示例有什么问题?

2 个答案:

答案 0 :(得分:2)

为什么不跳过使用SoundPlayer直接通过NAudio播放MP3? NAudio旨在实现这一目标。只需将MP3下载到某个地方的临时文件中,然后使用NAudio播放它,并在完成后删除临时文件。我不认为在下载文件时可以采取任何措施来减少延迟。

http://naudio.codeplex.com/wikipage?title=MP3

答案 1 :(得分:2)

根据Lee Harrison的回答,我已经创建了更好的替代代码。

(3)直接从WEB播放MP3文件而不转换为WAV并且不使用磁盘操作:

public void Speak(Uri mp3FileUri)
{
    using (var client = new WebClient())
    {
        using (var networkStream = client.OpenRead(mp3FileUri))
        {
            if (networkStream != null)
            {
                using (var memStream = new MemoryStream())
                {
                    networkStream.CopyTo(memStream);
                    memStream.Position = 0;                            
                    using (var waveOut = new WaveOut(WaveCallbackInfo.FunctionCallback()))
                    {
                        var waveEvent = new ManualResetEvent(false);
                        waveOut.PlaybackStopped += (sender, e) => waveEvent.Set();
                        waveEvent.Reset();
                        using (var rdr = new Mp3FileReader(memStream))
                        using (var waveStream = WaveFormatConversionStream.CreatePcmStream(rdr))
                        using (var baStream = new BlockAlignReductionStream(waveStream))
                        {
                            waveOut.Init(baStream);
                            waveOut.Play();
                            if (waveOut.PlaybackState != PlaybackState.Stopped)
                            { 
                                waveEvent.WaitOne(); /* block thread for a while because I don't want async play back                                
                                                        (to be analogical as usage of SoundPlayer Play method) */
                            }
                        }
                    }
                }
            }
        }
    }
}

尽管如此(尽管这对我来说非常好),我仍然不知道样本(2)的问题是什么。