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

using NAudio;using NAudio.Wave;

3.申请一个播放组件和一个音频文件读取

IWavePlayer waveOutDevice;AudioFileReader audioFileReader;

4.开始读取文件和播放音乐

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

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

using NVorbis;using NVorbis.NAudioSupport;

3. 加载ogg文件，并开始播放

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

/* 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, 		RightChannel, ChannelCount, SampleCount, Frequency);        }    }

4.将wav字节数组转为AudioClip

        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

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

#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。