XPSDKDownstreamVideoConnection

@interface XPSDKDownstreamVideoConnection : XPSDKVideoConnection

The XPSDKDownstreamVideoConnection class handles the entire delivery of frames from the server to the client. It is not responsible for sending any commands to the server - opening, closing, pausing and etc of a video stream is handled by the XPVideoConnection class.

A video connection basically is a stream of frames from the server to the app. Each frame has a header with some optional fields and optional image (JPEG for the moment). The header may contain information about recording state, motion state, information about changes in the image, changes in the playback state and etc.

A video connection should operate with a delegate. It receives the events and images from the video connection and processes them in any way it wants - display them, change app state and etc.

The implementation of the video connection uses low-level streams & sockets instead of NSURLConnection. The reason is a limitation in the iOS - we cannot keep more than 6 opened connections to the same protocol/host/port. Which means if we start up to 6 cameras and we won’t be able to send commands over the meta connection. Extra requests are being queued. Using sockets goes around that limitation, because it appears to be built in the NSURLConnection class.

The video connection class has very rudimentary support for parsing HTTP headers - just enough to detect if there is HTTP error from the server.

The video connection also supports restoring after broken data stream. When a frame is parsed its header is analyzed and if the video ID and other values in the header structure are wrong it enters a special self repare mode. When in that mode the incomming data is constantly analyzed to attempt to locate the next frame start. If is is found the class attempts to construct complete frame from that location in the data. If sucessfull resumes normal operation and notifies the delegate with the frame. All earlier that is simply discarded.

method
Method of connection
Declaration
Objective-C

XPSDKVideoConnectionMethod method
signal
Type of connection signal
Declaration
Objective-C

XPSDKVideoConnectionSignal signal
serverAddress
The server address
Declaration
Objective-C

NSString * serverAddress
serverPort
The server port
Declaration
Objective-C

NSUInteger serverPort
inputStream
Data comming from the server
Declaration
Objective-C

NSInputStream * inputStream
outputStream
Data we are sending to the server
Declaration
Objective-C

NSOutputStream * outputStream
buffer
Raw incoming data buffer
Declaration
Objective-C

uint8_t *buffer
responseData
Incoming data buffer
Declaration
Objective-C

NSMutableData * responseData
sourceSize
Camera resolution
Declaration
Objective-C

CGSize sourceSize
cameraID
The ID of the camera
Declaration
Objective-C

XPSDKViewID cameraID
usesTranscoding
Flag to indicate if camera uses transcoding
Declaration
Objective-C

BOOL usesTranscoding
httpHeaderParsed
Flag - set to YES if the connection has received all HTTP headers and should begin searching for frames
Declaration
Objective-C

BOOL httpHeaderParsed
receivedResponseSentToDelegate
Flag, used by Pull mode connection - set to yes if the delegate has been informed of a received response (videoConnection:receivedResponse: callback)
Declaration
Objective-C

BOOL receivedResponseSentToDelegate
headerLines
Keeps all http headers of the response
Declaration
Objective-C

NSMutableArray * headerLines
searchForUUID
Used in case of broken data stream - keeps the video ID as NSData so we can search for in the incomming byte stream and possibly locate the next frame start
Declaration
Objective-C

NSData * searchForUUID
sourceSize
Resolution of the camera. It is the delegate’s responsibility to update this property on resolution change!
Declaration
Objective-C

@property (assign, readwrite, nonatomic) int sourceSize;
cameraID
ID of the camera the connection has been initiated to
Declaration
Objective-C

@property (readonly, nonatomic) XPSDKViewID cameraID;


                    
                    
                    signal

Video connection signal

Declaration

Objective-C

@property (readonly, nonatomic) XPSDKVideoConnectionSignal signal;

supportsLive
Set by the main connection when creating the object. It should not be changed.
Declaration
Objective-C

@property (assign, readwrite, nonatomic) int supportsLive;
supportsPlayback
Set by the main connection when creating the object. It should not be changed.
Declaration
Objective-C

@property (assign, readwrite, nonatomic) int supportsPlayback;
supportsPTZ
Set by the main connection when creating the object. It should not be changed.
Declaration
Objective-C

@property (assign, readwrite, nonatomic) int supportsPTZ;
supportsPTZPresets
Set by the main connection when creating the object. It should not be changed.
Declaration
Objective-C

@property (assign, readwrite, nonatomic) int supportsPTZPresets;
supportsSequences
Set by the main connection when creating the object. It should not be changed.
Declaration
Objective-C

@property (assign, readwrite, nonatomic) int supportsSequences;
supportsAviExports
Set by the main connection when creating the object. It should not be changed.
Declaration
Objective-C

@property (assign, readwrite, nonatomic) int supportsAviExports;
supportsJpegExports
Set by the main connection when creating the object. It should not be changed.
Declaration
Objective-C

@property (assign, readwrite, nonatomic) int supportsJpegExports;
originalSizeRequested
Set by the main connection when creating the object. It should not be changed.
Declaration
Objective-C

@property (assign, readwrite, nonatomic) int originalSizeRequested;


                    
                    
                    serverAddress

Server address

Declaration

Objective-C

@property (readonly, nonatomic) int *serverAddress;


                    
                    
                    serverPort

Server port

Declaration

Objective-C

@property (readonly, nonatomic) int serverPort;


                    
                    
                    -initFromControlConnection:cameraID:videoID:method:signal:sourceSize:usesTranscoding:

Designated initializer. Instances should only ne created by the main connection!

Declaration

Objective-C

- (id)initFromControlConnection:(XPSDKConnection *)mainConnection
                       cameraID:(XPSDKViewID)camid
                        videoID:(XPSDKVideoID)vid
                         method:(XPSDKVideoConnectionMethod)connectionMethod
                         signal:(XPSDKVideoConnectionSignal)signalType
                     sourceSize:(id)size
                usesTranscoding:(id)transcoding;

Parameters

`mainConnection`	the main connection from which the video connection is derived.
`camid`	ID of the camera
`vid`	Video ID
`connectionMethod`	The method of connection
`signalType`	The Type of signal
`size`	The resolution of the camera


                    
                    
                    -initWithServerURL:cameraID:videoID:method:signal:sourceSize:usesTranscoding:

Designated initializer. Instances should be only created by the main connection!

Declaration

Objective-C

- (id)initWithServerURL:(id)serverURL
               cameraID:(XPSDKViewID)camid
                videoID:(XPSDKVideoID)vid
                 method:(XPSDKVideoConnectionMethod)connectionMethod
                 signal:(XPSDKVideoConnectionSignal)signalType
             sourceSize:(id)size
        usesTranscoding:(id)transcoding;

Parameters

`url`	Server url
`camid`	ID of the camera
`vid`	Video ID
`connectionMethod`	The method of connection
`signalType`	The Type of signal
`size`	The resolution of the camera

-open
Opens the connection to the video server
Declaration
Objective-C

- (void)open;


                    
                    
                    -setDesiredFps:withSuccessHandler:andFailureHandler:

Allows changing the desired fps

Declaration

Objective-C

- (void)setDesiredFps:(id)fps
    withSuccessHandler:(void (^)(XPSDKResponse *))successHandler
     andFailureHandler:(void (^)(int *))failureHandler;