我要玩使用NET所提供的 System.Media.SoundPlayer 机制。由于它与WAV格式,它需要如支持 n音讯库 - 我需要MP3转换为WAV。
I want to play MP3 file downloaded from the web using NET provided System.Media.SoundPlayer mechanism. As it works with WAV formats, it requires the support of e.g. NAudio library - I need to convert MP3 to WAV.
我想要做的所有操作在内存中,因为我需要它来进行所谓的快,但我有问题。下面我已经证明code的正常工作,但它与文件配合。相反,我需要它的工作只使用内存操作。
I want to do all operations in memory, as I need it to be so called fast, but I have problems. Below I've shown code which works as expected, but it cooperates with files. Instead I need to make it working using memory operations only.
(1)工作,但涉及磁盘操作:
(1) works, but involves disk operations:
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)不工作 - 不会抛出异常,但没有播放:
(2) doesn't work - no exception is thrown, but nothing is played:
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 ? */ } } } } } } }
怎样才可以做的,什么是错的第二个code样?
How can it be done and what is wrong with the second code sample ?
推荐答案根据李哈里森回答,我创建了替代code这是更好的。
Based on Lee Harrison answer, I've created alternative code which is better.
(3)直接播放MP3文件从WEB无需转换为WAV和无磁盘操作的用法:
(3) plays directly MP3 file from WEB without conversion to WAV and without usage of disk operations:
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) */ } } } } } } } }
不过(尽管这对我来说是相当不错的),我仍然不知道有什么用样品的问题(2)。
Nevertheless (despite this is quite good for me), I still don't know what's the problem with sample (2).
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