private void WorkerThread( )
{
// buffer to read stream
byte[] buffer = new byte[bufSize];
// JPEG magic number
byte[] jpegMagic = new byte[] { 0xFF, 0xD8, 0xFF };
int jpegMagicLength = 3;
ASCIIEncoding encoding = new ASCIIEncoding( );
while ( !stopEvent.WaitOne( 0, false ) )
{
// reset reload event
reloadEvent.Reset( );
// HTTP web request
HttpWebRequest request = null;
// web responce
WebResponse response = null;
// stream for MJPEG downloading
Stream stream = null;
// boundary betweeen images (string and binary versions)
byte[] boundary = null;
string boudaryStr = null;
// length of boundary
int boundaryLen;
// flag signaling if boundary was checked or not
bool boundaryIsChecked = false;
// read amounts and positions
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
request = (HttpWebRequest) WebRequest.Create( source );
// set user agent
if ( userAgent != null )
{
request.UserAgent = userAgent;
}
// set proxy
if ( proxy != null )
{
request.Proxy = proxy;
}
// set timeout value for the request
request.Timeout = requestTimeout;
// set login and password
if ( ( login != null ) && ( password != null ) && ( login != string.Empty ) )
request.Credentials = new NetworkCredential( login, password );
// set connection group name
if ( useSeparateConnectionGroup )
request.ConnectionGroupName = GetHashCode( ).ToString( );
// force basic authentication through extra headers if required
if ( forceBasicAuthentication )
{
string authInfo = string.Format( "{0}:{1}", login, password );
authInfo = Convert.ToBase64String( Encoding.Default.GetBytes( authInfo ) );
request.Headers["Authorization"] = "Basic " + authInfo;
}
// get response
response = request.GetResponse( );
// check content type
string contentType = response.ContentType;
string[] contentTypeArray = contentType.Split( '/' );
// "application/octet-stream"
if ( ( contentTypeArray[0] == "application" ) && ( contentTypeArray[1] == "octet-stream" ) )
{
boundaryLen = 0;
boundary = new byte[0];
}
else if ( ( contentTypeArray[0] == "multipart" ) && ( contentType.Contains( "mixed" ) ) )
{
// get boundary
int boundaryIndex = contentType.IndexOf( "boundary", 0 );
if ( boundaryIndex != -1 )
{
boundaryIndex = contentType.IndexOf( "=", boundaryIndex + 8 );
}
if ( boundaryIndex == -1 )
{
// try same scenario as with octet-stream, i.e. without boundaries
boundaryLen = 0;
boundary = new byte[0];
}
else
{
boudaryStr = contentType.Substring( boundaryIndex + 1 );
// remove spaces and double quotes, which may be added by some IP cameras
boudaryStr = boudaryStr.Trim( ' ', '"' );
boundary = encoding.GetBytes( boudaryStr );
boundaryLen = boundary.Length;
boundaryIsChecked = false;
}
}
else
{
throw new Exception( "Invalid content type." );
}
// get response stream
stream = response.GetResponseStream( );
stream.ReadTimeout = requestTimeout;
// loop
while ( ( !stopEvent.WaitOne( 0, false ) ) && ( !reloadEvent.WaitOne( 0, false ) ) )
{
// check total read
if ( total > bufSize - readSize )
{
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;
// do we need to check boundary ?
if ( ( boundaryLen != 0 ) && ( !boundaryIsChecked ) )
{
// some IP cameras, like AirLink, claim that boundary is "myboundary",
// when it is really "--myboundary". this needs to be corrected.
pos = ByteArrayUtils.Find( buffer, boundary, 0, todo );
// continue reading if boudary was not found
if ( pos == -1 )
continue;
for ( int i = pos - 1; i >= 0; i-- )
{
byte ch = buffer[i];
if ( ( ch == (byte) '\n' ) || ( ch == (byte) '\r' ) )
{
break;
}
boudaryStr = (char) ch + boudaryStr;
}
boundary = encoding.GetBytes( boudaryStr );
boundaryLen = boundary.Length;
boundaryIsChecked = true;
}
// search for image start
if ( ( align == 1 ) && ( todo >= jpegMagicLength ) )
{
start = ByteArrayUtils.Find( buffer, jpegMagic, pos, todo );
if ( start != -1 )
{
// found JPEG start
pos = start + jpegMagicLength;
todo = total - pos;
align = 2;
}
else
{
// delimiter not found
todo = jpegMagicLength - 1;
pos = total - todo;
}
}
// search for image end ( boundaryLen can be 0, so need extra check )
while ( ( align == 2 ) && ( todo != 0 ) && ( todo >= boundaryLen ) )
{
stop = ByteArrayUtils.Find( buffer,
( boundaryLen != 0 ) ? boundary : jpegMagic,
pos, todo );
if ( stop != -1 )
{
pos = stop;
todo = total - pos;
// increment frames counter
framesReceived ++;
// image at stop
if ( ( NewFrame != null ) && ( !stopEvent.WaitOne( 0, false ) ) )
{
System.Drawing.Bitmap bitmap = (System.Drawing.Bitmap)System.Drawing.Bitmap.FromStream(new MemoryStream(buffer, start, stop - start));
// notify client
NewFrame( this, new NewFrameEventArgs( bitmap ) );
// release the image
bitmap.Dispose( );
bitmap = null;
}
// shift array
pos = stop + boundaryLen;
todo = total - pos;
Array.Copy( buffer, pos, buffer, 0, todo );
total = todo;
pos = 0;
align = 1;
}
else
{
// boundary not found
if ( boundaryLen != 0 )
{
todo = boundaryLen - 1;
pos = total - todo;
}
else
{
todo = 0;
pos = total;
}
}
}
}
}
catch ( ApplicationException )
{
// do nothing for Application Exception, which we raised on our own
// wait for a while before the next try
Thread.Sleep( 250 );
}
catch ( ThreadAbortException )
{
break;
}
catch ( Exception exception )
{
// provide information to clients
if ( VideoSourceError != null )
{
VideoSourceError( this, new VideoSourceErrorEventArgs( exception.Message ) );
}
// wait for a while before the next try
Thread.Sleep( 250 );
}
finally
{
// abort request
if ( request != null)
{
request.Abort( );
request = null;
}
// close response stream
if ( stream != null )
{
stream.Close( );
stream = null;
}
// close response
if ( response != null )
{
response.Close( );
response = null;
}
}
// need to stop ?
if ( stopEvent.WaitOne( 0, false ) )
break;
}
if ( PlayingFinished != null )
{
PlayingFinished( this, ReasonToFinishPlaying.StoppedByUser );
}
}
}
