/// <summary>
/// Recursively merge all files in a directory with a WAV header
/// </summary>
/// <param name="dir">Merging directory</param>
/// <returns></returns>
private IEnumerable <FileInfo> CollapseWaves(DirectoryInfo dir)
{
const short CHANNELS = 1;
const int SAMPLE_RATE = 16000;
const short BITS_PER_SAMPLE = 16;
const int HEADER_SIZE = 44; //size of a wav header
//these are all case-sensitive / length-sensitive
const string RIFF = "RIFF";
const string WAVEfmt = "WAVEfmt ";
const string DATA = "data";
var files = dir.GetFiles().Where(f => f.Extension.ToLower() == ".wav" || f.Extension.ToLower() == ".efd");
if (files.Count() <= 1)
{
return(files);
}
else
{
//get first file in the directory
var first = new FileStream(files.ElementAt(0).FullName, FileMode.Open, FileAccess.Read);
//get second file
var second = new FileStream(files.ElementAt(1).FullName, FileMode.Open, FileAccess.Read);
//each file has a header, so add the total bytes and then subtract the header size for each
int length = (int)(first.Length + second.Length - (2 * HEADER_SIZE));
var merged = new FileStream(Path.Combine(dir.FullName, Path.GetRandomFileName()) + ".wav", FileMode.Create, FileAccess.Write);
var bw = new BinaryWriter(merged);
bw.Write(RIFF.ToCharArray());
bw.Write(length + HEADER_SIZE);
bw.Write(WAVEfmt.ToCharArray());
//chunk information and audio format info
bw.Write((int)16);
bw.Write((short)1);
bw.Write(CHANNELS);
bw.Write(SAMPLE_RATE);
bw.Write((int)(SAMPLE_RATE * ((BITS_PER_SAMPLE * CHANNELS) / 8)));
bw.Write((short)((BITS_PER_SAMPLE * CHANNELS) / 8));
bw.Write(BITS_PER_SAMPLE);
bw.Write(DATA.ToCharArray());
bw.Write(length);
//read the files with an offset of the headersize
byte[] arrFirst = new byte[first.Length];
first.Read(arrFirst, HEADER_SIZE, arrFirst.Length - HEADER_SIZE);
byte[] arrSecond = new byte[second.Length];
second.Read(arrSecond, HEADER_SIZE, arrSecond.Length - HEADER_SIZE);
first.Close();
second.Close();
bw.Write(arrFirst);
bw.Write(arrSecond);
bw.Close();
merged.Close();
//delete merged files
File.Delete(files.ElementAt(0).FullName);
File.Delete(files.ElementAt(1).FullName);
return(CollapseWaves(dir));
}
}
