www.pudn.com > motion.zip > MJPEGSource.cs
// Copyright © Andrew Kirillov, 2005
// andrew.kirillov@gmail.com
//
namespace videosource
{
using System;
using System.Drawing;
using System.IO;
using System.Text;
using System.Threading;
using System.Net;
///
/// MJPEGSource - MJPEG stream support
///
public class MJPEGSource : IVideoSource
{
private string source;
private string login = null;
private string password = null;
private object userData = null;
private int framesReceived;
private int bytesReceived;
private bool useSeparateConnectionGroup = true;
private const int bufSize = 512 * 1024; // buffer size
private const int readSize = 1024; // portion size to read
private Thread thread = null;
private ManualResetEvent stopEvent = null;
private ManualResetEvent reloadEvent = null;
// new frame event
public event CameraEventHandler NewFrame;
// SeparateConnectioGroup property
// indicates to open WebRequest in separate connection group
public bool SeparateConnectionGroup
{
get { return useSeparateConnectionGroup; }
set { useSeparateConnectionGroup = value; }
}
// VideoSource property
public string VideoSource
{
get { return source; }
set
{
source = value;
// signal to reload
if (thread != null)
reloadEvent.Set();
}
}
// Login property
public string Login
{
get { return login; }
set { login = value; }
}
// Password property
public string Password
{
get { return password; }
set { password = value; }
}
// FramesReceived property
public int FramesReceived
{
get
{
int frames = framesReceived;
framesReceived = 0;
return frames;
}
}
// BytesReceived property
public int BytesReceived
{
get
{
int bytes = bytesReceived;
bytesReceived = 0;
return bytes;
}
}
// UserData property
public object UserData
{
get { return userData; }
set { userData = value; }
}
// Get state of the video source thread
public bool Running
{
get
{
if (thread != null)
{
if (thread.Join(0) == false)
return true;
// the thread is not running, so free resources
Free();
}
return false;
}
}
// Constructor
public MJPEGSource()
{
}
// Start work
public void Start()
{
if (thread == null)
{
framesReceived = 0;
bytesReceived = 0;
// create events
stopEvent = new ManualResetEvent(false);
reloadEvent = new ManualResetEvent(false);
// create and start new thread
thread = new Thread(new ThreadStart(WorkerThread));
thread.Name = source;
thread.Start();
}
}
// Signal thread to stop work
public void SignalToStop()
{
// stop thread
if (thread != null)
{
// signal to stop
stopEvent.Set();
}
}
// Wait for thread stop
public void WaitForStop()
{
if (thread != null)
{
// wait for thread stop
thread.Join();
Free();
}
}
// Abort thread
public void Stop()
{
if (this.Running)
{
thread.Abort();
WaitForStop();
}
}
// Free resources
private void Free()
{
thread = null;
// release events
stopEvent.Close();
stopEvent = null;
reloadEvent.Close();
reloadEvent = null;
}
// Thread entry point
public void WorkerThread()
{
byte[] buffer = new byte[bufSize]; // buffer to read stream
while (true)
{
// reset reload event
reloadEvent.Reset();
HttpWebRequest req = null;
WebResponse resp = null;
Stream stream = null;
byte[] delimiter = null;
byte[] delimiter2 = null;
byte[] boundary = null;
int boundaryLen, delimiterLen = 0, delimiter2Len = 0;
int read, todo = 0, total = 0, pos = 0, align = 1;
int start = 0, stop = 0;
// align
// 1 = searching for image start
// 2 = searching for image end
try
{
// create request
req = (HttpWebRequest) WebRequest.Create(source);
// set login and password
if ((login != null) && (password != null) && (login != ""))
req.Credentials = new NetworkCredential(login, password);
// set connection group name
if (useSeparateConnectionGroup)
req.ConnectionGroupName = GetHashCode().ToString();
// get response
resp = req.GetResponse();
// check content type
string ct = resp.ContentType;
if (ct.IndexOf("multipart/x-mixed-replace") == -1)
throw new ApplicationException("Invalid URL");
// get boundary
ASCIIEncoding encoding = new ASCIIEncoding();
boundary = encoding.GetBytes(ct.Substring(ct.IndexOf("boundary=", 0) + 9));
boundaryLen = boundary.Length;
// get response stream
stream = resp.GetResponseStream();
// loop
while ((!stopEvent.WaitOne(0, true)) && (!reloadEvent.WaitOne(0, true)))
{
// check total read
if (total > bufSize - readSize)
{
System.Diagnostics.Debug.WriteLine("flushing");
total = pos = todo = 0;
}
// read next portion from stream
if ((read = stream.Read(buffer, total, readSize)) == 0)
throw new ApplicationException();
total += read;
todo += read;
// increment received bytes counter
bytesReceived += read;
// does we know the delimiter ?
if (delimiter == null)
{
// find boundary
pos = ByteArrayUtils.Find(buffer, boundary, pos, todo);
if (pos == -1)
{
// was not found
todo = boundaryLen - 1;
pos = total - todo;
continue;
}
todo = total - pos;
if (todo < 2)
continue;
// check new line delimiter type
if (buffer[pos + boundaryLen] == 10)
{
delimiterLen = 2;
delimiter = new byte[2] {10, 10};
delimiter2Len = 1;
delimiter2 = new byte[1] {10};
}
else
{
delimiterLen = 4;
delimiter = new byte[4] {13, 10, 13, 10};
delimiter2Len = 2;
delimiter2 = new byte[2] {13, 10};
}
pos += boundaryLen + delimiter2Len;
todo = total - pos;
}
// boundary aligned
/* if ((align == 0) && (todo >= boundaryLen))
{
if (ByteArrayUtils.Compare(buffer, boundary, pos))
{
// boundary located
align = 1;
todo -= boundaryLen;
pos += boundaryLen;
}
else
align = 2;
}*/
// search for image
if (align == 1)
{
start = ByteArrayUtils.Find(buffer, delimiter, pos, todo);
if (start != -1)
{
// found delimiter
start += delimiterLen;
pos = start;
todo = total - pos;
align = 2;
}
else
{
// delimiter not found
todo = delimiterLen - 1;
pos = total - todo;
}
}
// search for image end
while ((align == 2) && (todo >= boundaryLen))
{
stop = ByteArrayUtils.Find(buffer, boundary, pos, todo);
if (stop != -1)
{
pos = stop;
todo = total - pos;
// increment frames counter
framesReceived ++;
// image at stop
if (NewFrame != null)
{
Bitmap bmp = (Bitmap) Bitmap.FromStream(new MemoryStream(buffer, start, stop - start));
// notify client
NewFrame(this, new CameraEventArgs(bmp));
// release the image
bmp.Dispose();
bmp = null;
}
// System.Diagnostics.Debug.WriteLine("found image end, size = " + (stop - start));
// shift array
pos = stop + boundaryLen;
todo = total - pos;
Array.Copy(buffer, pos, buffer, 0, todo);
total = todo;
pos = 0;
align = 1;
}
else
{
// delimiter not found
todo = boundaryLen - 1;
pos = total - todo;
}
}
}
}
catch (WebException ex)
{
System.Diagnostics.Debug.WriteLine("=============: " + ex.Message);
// wait for a while before the next try
Thread.Sleep(250);
}
catch (ApplicationException ex)
{
System.Diagnostics.Debug.WriteLine("=============: " + ex.Message);
// wait for a while before the next try
Thread.Sleep(250);
}
catch (Exception ex)
{
System.Diagnostics.Debug.WriteLine("=============: " + ex.Message);
}
finally
{
// abort request
if (req != null)
{
req.Abort();
req = null;
}
// close response stream
if (stream != null)
{
stream.Close();
stream = null;
}
// close response
if (resp != null)
{
resp.Close();
resp = null;
}
}
// need to stop ?
if (stopEvent.WaitOne(0, true))
break;
}
}
}
}