Windows Phone 保存录音

Windows Phone 保存录音

前面介绍了Windows Phone 录制音频http://www.2cto.com/kf/201203/122741.html ，通过访问Windows Phone的麦克风进行录制音频。录制好的音频要保存为文件，需要做相关格式转换。一般录音的格式为.WAV，下面就介绍如何将录音保存为WAV文件。
　　1.在录制音频开始之前，首先要向音频流存储区audioStream中写入WAV文件头信息。即在调用microphone.Start()之前调用WriteWavHeader(audioStream, microphone.SampleRate)，其中WriteWavHeader函数实现如下。
  WriteWavHeader
 1 /// <summary>
 2 /// 写wav文件头信息
 3 /// </summary>
 4 /// <param name="stream"></param>
 5 /// <param name="sampleRate"></param>
 6 public void WriteWavHeader(Stream stream, int sampleRate)
 7 {
 8     const int bitsPerSample = 16;
 9     const int bytesPerSample = bitsPerSample / 8;
10     var encoding = System.Text.Encoding.UTF8;
11
12     // ChunkID Contains the letters "RIFF" in ASCII form (0x52494646 big-endian form).
13     stream.Write(encoding.GetBytes("RIFF"), 0, 4);
14
15     // NOTE this will be filled in later
16     stream.Write(BitConverter.GetBytes(0), 0, 4);
17
18     // Format Contains the letters "WAVE"(0x57415645 big-endian form).
19     stream.Write(encoding.GetBytes("WAVE"), 0, 4);
20
21     // Subchunk1ID Contains the letters "fmt " (0x666d7420 big-endian form).
22     stream.Write(encoding.GetBytes("fmt "), 0, 4);
23
24     // Subchunk1Size 16 for PCM.  This is the size of therest of the Subchunk which follows this number.
25     stream.Write(BitConverter.GetBytes(16), 0, 4);
26
27     // AudioFormat PCM = 1 (i.e. Linear quantization) Values other than 1 indicate some form of compression.
28     stream.Write(BitConverter.GetBytes((short)1), 0, 2);
29
30     // NumChannels Mono = 1, Stereo = 2, etc.
31     stream.Write(BitConverter.GetBytes((short)1), 0, 2);
32
33     // SampleRate 8000, 44100, etc.
34     stream.Write(BitConverter.GetBytes(sampleRate), 0, 4);
35
36     // ByteRate =  SampleRate * NumChannels * BitsPerSample/8
37     stream.Write(BitConverter.GetBytes(sampleRate * bytesPerSample), 0, 4);
38
39     // BlockAlign NumChannels * BitsPerSample/8 The number of bytes for one sample including all channels.
40     stream.Write(BitConverter.GetBytes((short)(bytesPerSample)), 0, 2);
41
42     // BitsPerSample    8 bits = 8, 16 bits = 16, etc.
43     stream.Write(BitConverter.GetBytes((short)(bitsPerSample)), 0, 2);
44
45     // Subchunk2ID Contains the letters "data" (0x64617461 big-endian form).
46     stream.Write(encoding.GetBytes("data"), 0, 4);
47
48     // NOTE to be filled in later
49     stream.Write(BitConverter.GetBytes(0), 0, 4);
50 }

　　2.在录制音频结束的时候，才能确认录音文件大小的长度，此时需要修改WAV文件头部分信息。即在调用microphone.Stop()之后调用UpdateWavHeader(audioStream)，其中UpdateWavHeader函数实现如下。
  UpdateWavHeader
 1 /// <summary>
 2 /// 更新wav文件头信息
 3 /// </summary>
 4 /// <param name="stream"></param>
 5 public void UpdateWavHeader(Stream stream)
 6 {
 7     if (!stream.CanSeek) throw new Exception("Can't seek stream to update wav header");
 8
 9     var oldPos = stream.Position;
10
11     // ChunkSize  36 + SubChunk2Size
12     stream.Seek(4, SeekOrigin.Begin);
13     stream.Write(BitConverter.GetBytes((int)stream.Length - 8), 0, 4);
14
15     // Subchunk2Size == NumSamples * NumChannels * BitsPerSample/8 This is the number of bytes in the data.
16     stream.Seek(40, SeekOrigin.Begin);
17     stream.Write(BitConverter.GetBytes((int)stream.Length - 44), 0, 4);
18
19     stream.Seek(oldPos, SeekOrigin.Begin);
20 }

　　3.通过以上处理后的audioStream流已经是格式化后的WAV流。接下来只需要将audioStream流写入独立存储中(yu.wav)。
  View Code
        //将数据流转换为byte，recording中即为音频数据
        byte[] recording = audioStream.ToArray();
        //独立存储文件处理
        using (IsolatedStorageFile myIsolatedStorage = IsolatedStorageFile.GetUserStoreForApplication())
        {
            try
            {
                //打开文件
                using (IsolatedStorageFileStream fileStream = new IsolatedStorageFileStream("yu.wav", FileMode.Create, myIsolatedStorage))
                {
                    fileStream.Write(recording, 0, recording.Length);
                }
            }
            catch (Exception ex)
            {
                //读取失败
            }
        }

 

摘自  宇之乐