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本文介绍Unity开发中,在运行时加载外部音频(mp3/wav)的方法,非 WWW 或 UnityWebRequest,需要www方式的同学请自行baidu。
参考库:
github地址(都是NAudio名下的)
NAudio
输入:mp3文件
输出:AudioClip
- // Use NAudio
- // file => mp3 byte[] => {NAudio} => wav byte[] => AudioClip
-
- using System;
- using System.IO;
- using NAudio.Wave;
- // parse mp3
- AudioClip LoadMp3Audio(byte[] audioBytes, string fileName)
- {
- MemoryStream mp3stream = new MemoryStream(audioBytes);
- Mp3FileReader mp3audio = new Mp3FileReader(mp3stream);
- WaveStream waveStream = WaveFormatConversionStream.CreatePcmStream(mp3audio);
- 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();
- }
- byte[] wavBytes = outputStream.ToArray();
- return LoadWavAudio(wavBytes, fileName);
- }
- // parse wav
- AudioClip LoadWavAudio(byte[] audioBytes, string fileName)
- {
- // WAV 自定义wav解析类
- WAV wav = new WAV(audioBytes);
- AudioClip audioClip;
- if (wav.ChannelCount == 2)
- {
- audioClip = AudioClip.Create(fileName, wav.SampleCount, 2, wav.Frequency, false);
- audioClip.SetData(wav.StereoChannel, 0);
- }
- else
- {
- audioClip = AudioClip.Create(fileName, wav.SampleCount, 1, wav.Frequency, false);
- audioClip.SetData(wav.LeftChannel, 0);
- }
- return audioClip;
- }
- // 逻辑不完整,但是能用,所以只要你和代码一个能跑就可以了
- 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 float[] StereoChannel { 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;
- while (pos < wav.Length)
- {
- LeftChannel[i] = bytesToFloat(wav[pos], wav[pos + 1]);
- pos += 2;
- if (ChannelCount == 2)
- {
- RightChannel[i] = bytesToFloat(wav[pos], wav[pos + 1]);
- pos += 2;
- }
- i++;
- }
-
- //Merge left and right channels for stereo sound
- if (ChannelCount == 2)
- {
- StereoChannel = new float[SampleCount * 2];
- //Current position in our left and right channels
- int channelPos = 0;
- //After we've changed two values for our Stereochannel, we want to increase our channelPos
- short posChange = 0;
-
- for (int index = 0; index < (SampleCount * 2); index++)
- {
-
- if (index % 2 == 0)
- {
- StereoChannel[index] = LeftChannel[channelPos];
- posChange++;
- }
- else
- {
- StereoChannel[index] = RightChannel[channelPos];
- posChange++;
- }
- //Two values have been changed, so update our channelPos
- if (posChange % 2 == 0)
- {
- if (channelPos < SampleCount)
- {
- channelPos++;
- //Reset the counter for next iterations
- posChange = 0;
- }
- }
- }
- }
- else
- {
- StereoChannel = null;
- }
-
- Debug.Log($"mpegFile.Length={wav.Length},ChannelCount={ChannelCount},lenSample={LeftChannel.Length}");
- }
- }
NLayer
- // NLayer
- // file => mp3 byte[] => {MpegFile} => {ReadSamples} => sample float[] => AudioClip
- // 重点是ReadSamples方法的使用
-
- using NLayer;
-
- AudioClip LoadMp3Audio(byte[] audioBytes, string fileName)
- {
- System.IO.Stream memStream = new System.IO.MemoryStream(audioBytes);
- var mpegFile = new MpegFile(memStream);
- int lengthSamples = (int)(mpegFile.Length / sizeof(float) / mpegFile.Channels);
- float[] samples = new float[lengthSamples * mpegFile.Channels];
- int readCount = mpegFile.ReadSamples(samples, 0, lengthSamples * mpegFile.Channels);
- AudioClip ac = AudioClip.Create(fileName, lengthSamples, mpegFile.Channels, mpegFile.SampleRate, false);
- ac.SetData(samples, 0);
- return ac;
- }
- // wav加载同NAudio部分
参考:
改进加载效果:
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