unity使用NAudio/NVorbis加载外部音频文件

原文链接:http://gad.qq.com/article/detail/7182188
本文首发腾讯GAD开发者平台，未经允许，不得转载

首先说一下起因，我这里有需求将音频文件加密，所以一般的组件和www加载都不能使用，于是我需要一种新的方案来加载音频文件。于是我找到了一个开源的音频处理类库NAudio来处理MP3和wav的音频文件，同时我还需要使用到ogg的音频格式，后面还找到了NVorbis，我这里也是初步探索，顺便发篇博客分享一下。

一、资料准备
1.NAudio的链接:http://naudio.codeplex.com/，里面有相关的介绍和详细的文档，对unity3d还有一个插件，https://www.assetstore.unity3d.com/en/#!/content/32034 ，我并没有机会下载下来学习一下，只是简单使用了NAudio的几个接口，后面有兴趣的可以和我一起研究一下NAudio。
2.NVorbis的链接:http://nvorbis.codeplex.com/ ,这里是支持ogg需要下载的类库，后面我实用到相关的接口，我再给出详细的文档链接。
3.从NAudio和NVorbis下载发布的dll文件放在unity中，NVorbis还需要导入NVorbis.NAudioSupport.dll后面需要使用NAudio来播放ogg，记得将unity的Api Compatibility Level 改为.NET 2.0。

二、在unity中播放外部的MP3音频文件
1.文档链接http://naudio.codeplex.com/wikipage?title=MP3
2.使用命名空间
[csharp] view plain copy
using NAudio;
using NAudio.Wave;
3.申请一个播放组件和一个音频文件读取
[csharp] view plain copy
IWavePlayer waveOutDevice;
AudioFileReader audioFileReader;
4.开始读取文件和播放音乐
[csharp] view plain copy
void Start (){
waveOutDevice = new WaveOut();
audioFileReader = new AudioFileReader(@"D:\影音文件\音乐\BEYOND\黄家驹 - 总有爱.mp3");
waveOutDevice.Init(audioFileReader);
waveOutDevice.Play();
}
5. 注意在程序中退出的关闭音乐播放组件，因为他并不是使用unity在播放声音，而且使用自带的组件播放的了
[csharp] view plain copy
void OnApplicationQuit()
{
if (waveOutDevice != null)
{
waveOutDevice.Stop();
}
if (waveOutDevice != null)
{
waveOutDevice.Dispose();
waveOutDevice = null;
}
}
6. 还有这里加载wav也是同样可以播放的，同时应该也可以试试其他格式的音频比如aiff,但是不支持ogg，下面我会单独再来使用ogg。

三、在unity播放外部的ogg音频文件
1.文档链接:http://nvorbis.codeplex.com/documentation ,我这里还是会使用NAudio来播放
2.使用命名空间
[csharp] view plain copy
using NVorbis;
using NVorbis.NAudioSupport;
3. 加载ogg文件，并开始播放
[csharp] view plain copy
void Start (){
waveOutDevice = new WaveOut();
VorbisWaveReader oggReader = new VorbisWaveReader(@"D:\侧田 - 感动.ogg");
waveOutDevice.Init(oggReader);
waveOutDevice.Play();
}

四、将外部的音频文件转为unity的AudioClip
1.按着以上的方法来播放音乐是否感觉特别简单了，但是在实际使用中，如果是加载外部音频文件，我知道肯定有人还是觉得使用www来加载感觉更方便一些。于是我决定再来啰嗦一下，如果使用www外部加载时不能加载MP3格式的音频文件，但是目前MP3格式的音频文件确实最多的，还有一个重要因素是，我目前解密出来的音频文件是一堆字节数组，而且我也不知道不同音频应该怎样去解码，如果我再把字节数组去写成一个音频文件再用www来读取，那确实有点闲得蛋疼的感觉了。于是下面就是来实现怎样利用NAudio和NVorbis把一堆字节数组转成unity的AudioClip，使用unity的AudioSource来播放。
2. mp3/wav字节数组转AudioClip，具体给出代码来了，参考链接:http://gamedev.stackexchange.com/questions/114885/how-do-i-play-mp3-files-in-unity-standalone
3.自定义Wav格式，这里修复了RightChannel不为null时的最大输入判断
[csharp] view plain copy
/* From http://answers.unity3d.com/questions/737002/wav-byte-to-audioclip.html */
public class WAV
{

// convert two bytes to one float in the range -1 to 1
static float bytesToFloat(byte firstByte, byte secondByte)
{
// convert two bytes to one short (little endian)
short s = (short)((secondByte << 8) | firstByte);
// convert to range from -1 to (just below) 1
return s / 32768.0F;
}

static int bytesToInt(byte[] bytes, int offset = 0)
{
int value = 0;
for (int i = 0; i < 4; i++)
{
value |= ((int)bytes[offset + i]) << (i * 8);
}
return value;
}
// properties
public float[] LeftChannel { get; internal set; }
public float[] RightChannel { get; internal set; }
public int ChannelCount { get; internal set; }
public int SampleCount { get; internal set; }
public int Frequency { get; internal set; }

public WAV(byte[] wav)
{

// Determine if mono or stereo
ChannelCount = wav[22]; // Forget byte 23 as 99.999% of WAVs are 1 or 2 channels

// Get the frequency
Frequency = bytesToInt(wav, 24);

// Get past all the other sub chunks to get to the data subchunk:
int pos = 12; // First Subchunk ID from 12 to 16

// Keep iterating until we find the data chunk (i.e. 64 61 74 61 ...... (i.e. 100 97 116 97 in decimal))
while (!(wav[pos] == 100 && wav[pos + 1] == 97 && wav[pos + 2] == 116 && wav[pos + 3] == 97))
{
pos += 4;
int chunkSize = wav[pos] + wav[pos + 1] * 256 + wav[pos + 2] * 65536 + wav[pos + 3] * 16777216;
pos += 4 + chunkSize;
}
pos += 8;

// Pos is now positioned to start of actual sound data.
SampleCount = (wav.Length - pos) / 2; // 2 bytes per sample (16 bit sound mono)
if (ChannelCount == 2) SampleCount /= 2; // 4 bytes per sample (16 bit stereo)

// Allocate memory (right will be null if only mono sound)
LeftChannel = new float[SampleCount];
if (ChannelCount == 2) RightChannel = new float[SampleCount];
else RightChannel = null;

// Write to double array/s:
int i = 0;
int maxInput = wav.Length - (RightChannel == null ? 1 : 3);
// while (pos < wav.Length)
while ((i<SampleCount)&&( pos < maxInput))
{
LeftChannel[i] = bytesToFloat(wav[pos], wav[pos + 1]);
pos += 2;
if (ChannelCount == 2)
{
RightChannel[i] = bytesToFloat(wav[pos], wav[pos + 1]);
pos += 2;
}
i++;
}
}

public override string ToString()
{
return string.Format("[WAV: LeftChannel={0}, RightChannel={1}, ChannelCount={2}, SampleCount={3}, Frequency={4}]", LeftChannel,
<span style="white-space:pre"> </span>RightChannel, ChannelCount, SampleCount, Frequency);
}
}
4.将wav字节数组转为AudioClip
[csharp] view plain copy
public static AudioClip FromWavData(byte[] data)
{
WAV wav = new WAV(data);
AudioClip audioClip = AudioClip.Create("wavclip", wav.SampleCount, 1, wav.Frequency, false);
audioClip.SetData(wav.LeftChannel, 0);
return audioClip;
}
5.将MP3字节数组转为AudioClip
[csharp] view plain copy
public static AudioClip FromMp3Data(byte[] data)
{
// Load the data into a stream
MemoryStream mp3stream = new MemoryStream(data);
// Convert the data in the stream to WAV format
Mp3FileReader mp3audio = new Mp3FileReader(mp3stream);

WaveStream waveStream = WaveFormatConversionStream.CreatePcmStream(mp3audio);
// Convert to WAV data
WAV wav = new WAV(AudioMemStream(waveStream).ToArray());
//Debug.Log(wav);
AudioClip audioClip = AudioClip.Create("testSound", wav.SampleCount, 1, wav.Frequency, false);
audioClip.SetData(wav.LeftChannel, 0);
// Return the clip
return audioClip;
}

private static MemoryStream AudioMemStream(WaveStream waveStream)
{
MemoryStream outputStream = new MemoryStream();
using (WaveFileWriter waveFileWriter = new WaveFileWriter(outputStream, waveStream.WaveFormat))
{
byte[] bytes = new byte[waveStream.Length];
waveStream.Position = 0;
waveStream.Read(bytes, 0, Convert.ToInt32(waveStream.Length));
waveFileWriter.Write(bytes, 0, bytes.Length);
waveFileWriter.Flush();
}
return outputStream;
}
}
6.将ogg字节数组转AudioClip，参考链接:http://answers.unity3d.com/questions/499028/onaudioread-buffer-changing-sizes.htm
[csharp] view plain copy
#region ogg字节转AudioClip
static NVorbis.VorbisReader vorbis;
public static AudioClip FromOggData(byte[] data)
{
// Load the data into a stream
MemoryStream oggstream = new MemoryStream(data);

vorbis = new NVorbis.VorbisReader(oggstream, false);

int samplecount = (int)(vorbis.SampleRate * vorbis.TotalTime.TotalSeconds);

// AudioClip audioClip = AudioClip.Create("clip", samplecount, vorbis.Channels, vorbis.SampleRate, false, true, OnAudioRead, OnAudioSetPosition);
AudioClip audioClip= AudioClip.Create("ogg clip", samplecount, vorbis.Channels, vorbis.SampleRate, false, OnAudioRead);
// Return the clip
return audioClip;
}
static void OnAudioRead(float[] data)
{
var f = new float[data.Length];
vorbis.ReadSamples(f, 0, data.Length);
for (int i = 0; i < data.Length; i++)
{
data[i] = f[i];
}
}
static void OnAudioSetPosition(int newPosition)
{
vorbis.DecodedTime = new TimeSpan(newPosition); //Only used to rewind the stream, we won't be seeking
}
#endregion

7.这里我给出了很多的相关链接，都是我在查找NAudio的资料，对我使用有帮助的一些文章，也分享给大家一起学习。而且NAudio好像还支持读取midi文件与合并mp3等很多功能，有兴趣可以持续关注。