我在AgileIM的开发中解决视频/音频会话功能时，发现传输的音/视频数据量太大，通过一些格式转换（如BMP->JPG、或 帧间预测编码）可以适当减少带宽的需求，但是仍然不能满足需求，于是我想到了数据压缩，经过我测试、普通的音/视频数据经压缩后可以只有原来的一半大小，基本可以满足需要了。压缩/解压功能我借助了ICSharpCode.SharpZipLib 类库，为了更方便易用，我封装了ZipHelper类，实现如下：
public
static
class
ZipHelper
{
public static byte [] Zip( byte [] data)
{
MemoryStream mstream = new MemoryStream();
BZip2OutputStream zipOutStream = new BZip2OutputStream(mstream);
zipOutStream.Write(data, 0 , data.Length);
zipOutStream.Finalize();
zipOutStream.Close();
byte [] result = mstream.ToArray();
mstream.Close();
return result;
}
public static byte [] Unzip( byte [] data)
{
MemoryStream mstream = new MemoryStream(data);
BZip2InputStream zipInputStream = new BZip2InputStream(mstream);
byte [] byteUncompressed = new byte [zipInputStream.Length];
zipInputStream.Read(byteUncompressed, 0 , ( int )byteUncompressed.Length);
zipInputStream.Close();
mstream.Close();
return byteUncompressed;
}
}
{
public static byte [] Zip( byte [] data)
{
MemoryStream mstream = new MemoryStream();
BZip2OutputStream zipOutStream = new BZip2OutputStream(mstream);
zipOutStream.Write(data, 0 , data.Length);
zipOutStream.Finalize();
zipOutStream.Close();
byte [] result = mstream.ToArray();
mstream.Close();
return result;
}
public static byte [] Unzip( byte [] data)
{
MemoryStream mstream = new MemoryStream(data);
BZip2InputStream zipInputStream = new BZip2InputStream(mstream);
byte [] byteUncompressed = new byte [zipInputStream.Length];
zipInputStream.Read(byteUncompressed, 0 , ( int )byteUncompressed.Length);
zipInputStream.Close();
mstream.Close();
return byteUncompressed;
}
}
ICSharpCode.SharpZipLib 类库可以从这里下载。
