如何在Windows Phone 8中将音频流保存为.aac格式文件

Question

我目前正在Windows Phone 8应用程序中将音频流保存为.wav文件。将流保存为.aac文件需要进行哪些更改？

public void saveAudioBuffer()
    {


        IsolatedStorageFile myStore = IsolatedStorageFile.GetUserStoreForApplication();


        //create a random file name and then assign
        Random rand = new Random(DateTime.Now.Millisecond);
        int rvalue = rand.Next(1000000000, 2000000000);
        newAudioFileName = "NEW_AUDIO_" + rvalue + "_FILE_NAME.wav";

       string fileName = ConfigurationInfo.savedFilesDirectory + newAudioFileName;
        if(myStore.FileExists(fileName))
           myStore.DeleteFile(fileName);
        try
        {

            using (var isoFileStream = new IsolatedStorageFileStream(
                fileName,
                FileMode.OpenOrCreate,
                myStore))
            {
                // Write a header before the actual pcm data
                int sampleBits = 16;
                int sampleBytes = sampleBits / 8;
                int byteRate = microphone.SampleRate * sampleBytes * 1;
                int blockAlign = sampleBytes * 1;
                Encoding encoding = Encoding.UTF8;

                isoFileStream.Write(encoding.GetBytes("RIFF"), 0, 4);                       // "RIFF"
                isoFileStream.Write(BitConverter.GetBytes(0), 0, 4);                        // Chunk Size
                isoFileStream.Write(encoding.GetBytes("WAVE"), 0, 4);                       // Format - "Wave"
                isoFileStream.Write(encoding.GetBytes("fmt "), 0, 4);                       // sub chunk - "fmt"
                isoFileStream.Write(BitConverter.GetBytes(16), 0, 4);                       // sub chunk size
                isoFileStream.Write(BitConverter.GetBytes((short)1), 0, 2);                 // audio format
                isoFileStream.Write(BitConverter.GetBytes((short)1), 0, 2);                 // num of channels
                isoFileStream.Write(BitConverter.GetBytes(microphone.SampleRate), 0, 4);    // sample rate
                isoFileStream.Write(BitConverter.GetBytes(byteRate), 0, 4);                 // byte rate
                isoFileStream.Write(BitConverter.GetBytes((short)(blockAlign)), 0, 2);      // block align
                isoFileStream.Write(BitConverter.GetBytes((short)(sampleBits)), 0, 2);      // bits per sample
                isoFileStream.Write(encoding.GetBytes("data"), 0, 4);                       // sub chunk - "data"
                isoFileStream.Write(BitConverter.GetBytes(0), 0, 4);                        // sub chunk size

                // write the actual pcm data
                stream.Position = 0;
                stream.CopyTo(isoFileStream);

                // and fill in the blanks
                long previousPos = isoFileStream.Position;
                isoFileStream.Seek(4, SeekOrigin.Begin);
                isoFileStream.Write(BitConverter.GetBytes((int)isoFileStream.Length - 8), 0, 4);
                isoFileStream.Seek(40, SeekOrigin.Begin);
                isoFileStream.Write(BitConverter.GetBytes((int)isoFileStream.Length - 44), 0, 4);
                isoFileStream.Seek(previousPos, SeekOrigin.Begin);

                isoFileStream.Flush();
            }
        }
        catch
        {
            MessageBox.Show("Error while trying to store audio stream.");
        }
    }

在我的应用程序中，我使用了Microsoft.Xna.Framework.Audio中的Microphone对象来捕获声音。