Technical Documentation
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1. The DoActivate method of this class is used for creating the lower containers It exists by default in the standard Symbian template but it was extended so that it also starts the recorder viewfinder which creates a camera object and runs the Engine which is the base for recording operations SetupStatusPaneL if iRecorderContainer lt lt NULL iRecorderContainer CreateContainerL iRecorderContainer gt SetMopParent this AppUi gt AddToStackL this iRecorderContainer H RecorderContainer gt Finder gt StartL Engine CRecorderEngine NewL getRecorderContainer gt Finder gt CameraHandle ens The CRecorderContainer class is used as a layout for the recorder viewfinder It is usually used for text and data Page 13 LiveTV Technical documentation Date 2010 01 15 displaying but since the application only uses the viewfinder it has been made transparent so that it does not interfere with the viewfinder itself After the transparency check the viewfinder is created and applied to the container The applying is made with Rect objects which are passed to the viewfinder The viewfinder has the CRecorderContainer as its Rect Later we can see the code for transparent container CWindowGc amp gc SystemGc gc Clear gc SetDrawMode CGraphicsContext EDrawModeWriteAlpha Gen seeBaush Colom MRI OOE gc Clear These three classes are all added by the IDE when st2. IMG MES M79 2 4 WIL 2 destIP Input IPaddress destPort 20000 width 176 height 144 frameRate 15 password Append L8 202020 username Append L8 livetv La iState EStateldle There is no other activity in the Engine until the button for start of recording is pressed The Record method is then called MediaRecorder API defines a specific way of starting a recording which is implemented in this method It consists of opening the CCMRMediaRecorder object previously defined with the specified audio and video codecs The MediaRecorder API specifications define a sink which will receive the video and audio frames when they are recorder We use the CRecorderSink object for that if iState lt EStateReadyToRecord TMMFMessageDestinationPckg pckg TMMFUidPckg uidPckg KUidMmfAudiolnput iAudioSource MDataSource NewSourceL uidPckg KNullDesC8 iRecorder gt OpenL this iAudioSource iSink iCameraHandle aMimeType aAudioType After that settings which can be set from the application are enabled frame rate resolution quality Unfortunately only the 176x144 resolution is available for h263 format video It may support higher resolutions but only with a higher quality but this wasn t successfully accomplished This ends the OpenL method Before we start the recording we have to start the RTP connection The RTP object is created in the CRecorderSink class which wi
3. Streaming is implemented in separate classes so it could easily be reused in similar applications Every class used for streaming implements StreamSender interface This interface defines four methods that are used to control the life cycle of the streaming class Methods defined in the StreamSender interface are listed here public abstract void prepare throws Exception public abstract void start public abstract void stop public abstract void release Prepare should be called before any other method defined in StreamSender interface this method is used to initialize the required Android classes that are used for recording After that start and stop can be called to start or stop the recording and streaming process In the end release should be called to release all resources owned by the object Classes VideoStreamSender AudioStreamSender and RawAudioStreamSender implement the StreamSender interface All of these classes are abstract because they also implement Runnable interface and do not define the run method These classes contain the code required to setup and control the Android classes MediaRecorder and AudioRecord that are used for recording VideoStreamSender and AudioStreamSender classes use MediaRecorder class to send encoded video or audio content while the RawAudioStreamSender uses AudioRecord class to get the raw audio bytes These classes implement Runnable interface because they create a new thread which will ex
4. 1 Player main class which is responsible to manage everything 2 TappableSurfaceView this class is responsible to handle user requests such as click on the different parts of application 3 URLHistory this class is responsible to save different URLs so that user does not need to type all URL paths each time 4 Historyltem this class is used by URLHistory class and it contains one URL item 5 SocketClient this class is used for sending UDP message to server and it is implemented because of feedback feature which is not completed in other parts of project 6 SocketServer same as socketClient 4 1 Player In this class we are controlling everything On initialization phase user interface components are built in onCreate method public void onCreate Bundle icicle super onCreate icicle Thread setDefaultUncaughtExceptionHandler onBlooey setContentView R layout main surface TappableSurfaceView findViewById R id surface surface addTapListener onTap holder surface getHolder holder addCallback this holder setType SurfaceHolder SURFACE TYPE PUSH BUFFERS topPanel lt findViewById R id top panel bottomPanel findViewById R id bottom panel timeline ProgressBar findViewById R id timeline media ImageButton findViewById R id media media setOnClickListener onMedia go Button findViewById R id go go setOnClickListener onGo address AutoCompleteTe
5. unmute There is also a function that allows associating a player that used VLC with a panel into the user interface 9 3 2 VideoPlayer This class is the link between the wrapper and the studio application 9 3 3 VideoPlayerManager This class allows to manage the set of players running into the application There are some functions that can modify the comportment of one player and affecting all the other players in contrary The function UpdateSound allows to mute all players except the one in parameter UpdateLive allows to modify the border of every player 9 4 LibVIc wrapper LibVlc is a library that can be used in Net project But a wrapper has to be written in order to use this library In our project we used the one that Marx Bitware support marxbitware com We didn t have to modify it Page 34 LiveTV Technical documentation Date 2010 01 15 List of Tables Page 35
6. 4 getvideoEncoder 4 setvideoEncoder 4 getvideoFrameSize 4 setvideoFrameSize getvideoPayloadType setvideoPayloadType setSurfaceHolder 4 prepare stato stopo release H RtpH263VideoStreamSender poj RtpH263VideoStreamSender runo Figure 2 Class diagram If AudioStreamSender F AudioStreamSender getLocalAudioPort setLocalAudioPort getRemoteAddress setRemoteAddresst getRemoteAudioPort setRemoteAudioPort getOutputFormat setOutputFormat getAudioEncoder setAudioEncoder getAudioFrameSize setAudioFrameSize getAudioPayloadType setAudioPayloadTypet 4 skipHeaders 4 preparel stato g stopil release H RtpAMRAudioStreamSender F RtpAMRAudioStreamSender runo H263 video frames can be of variable length Because of that it is necessary to determine where one frames stops and another starts This can be done by searching for the end of frame marker which is represented by two consecutive bytes of zeros 00 00 RtpH263VideoStreamSender does this in order to extract the H263 frames from the recorded stream and send them using RTP protocol Before the video frame is sent reguired headers are inserted before the frame as defined in the RFC4629 If the video frame is larger than the MTU size then it will be split into two or more packets whose individual sizes will be less than MTU Page 10 LiveTV Technica
7. CRecorderContainerView e CRecorderContainer First is the CRecorderAppUi class which was already mentioned It is used for creating containers and handling various key presses When a key is pressed a method in this class is called This is only for the hardware keys on the device When a menu key or button is pressed this is transferred to another class which deals with those keypresses This is standard Symbian template for key handling Other than creating the containers this class Page 12 LiveTV Technical documentation Date 2010 01 15 doesn t have any other purpose The method which creates the container is nitializeContainersL An application can have more than one view In this case view switching container switching is implemented in this class Other than that it needs to be mentioned that during construction of the AppUi class object an option is enabled which locks the application in landscape mode only because the accelerometer in the phone can change that otherwise The CRecorderContainerView class is the most important class of the entire graphical user interface During construction the user interface is created The creation process isn t in this class This class only calls a base constructor with a pointer to menu description The menu description is in another file and is created by the GUI Designer This class creates the lower containers which are used to display the recorder viewfinder It is also used to hand
8. LiveTV Technical documentation Date 2010 01 15 void onDestroy These methods are hooks that can be overridden to do appropriate work when the activity changes states These methods define a life cycle of an activity The following diagram illustrates life cycle of an activity The colored ovals are major states the activity can be in The sguare rectangles represent the callback methods you can implement to perform operations when the activity transitions between states Page 5 LiveTV Technical documentation Date 2010 01 15 User navigates onCreate back to the The activity comes to the foreground Another activity comes in front of the activi The activity Other applications comes to the need memo onPause foreground The activity is no longer visible onDestroy Figure 1 Life cycle of an Android activity Besides the source code Android applications usually contain some additional resources Most of the resources are defined using XML files For example layout of the user interface animations constants can all be defined using XML files Every Android application has a directory for resources res and a directory for assets assets Difference between resources and assets directory is that anything in the resources directory is easily accessible through the R class which is compiled by Android Whereas anything in the assets directory Page 6 LiveTV Technical documentation Dat
9. RTP protocol are from the SipDroid open source project Two classes are used for streaming content using RTP protocol these are RtpPacket and RtpSocket RtpPacket is formed from the data that will be sent and defines the required RTP headers RtpSocket class is used to send an RtpPacket to a remote server This class reads the RTP headers and payload data from the RtpPacket and sends it over the network Page 9 LiveTV Technical documentation Date 2010 01 15 The following figure shows the class diagram with the classes described in this chapter RawAudioStreamSender F Raw AudioStreamSender 4 getPayloadType setPayloadType getFrameSize 4 setFrameSize getSampleRate 4 amp setSampleRate 4 isMutedQ g setMuted getRemoteAddress s setRemoteAddress 4 getRemotePort 4 setRemotePort getLocalPort s setLocalPort prepare stato s stopi release H RtpG711AudioStreamSender poj RtpG711 AudioStreamSender g runo 2 4 1 H263 video interface E StreamSender 4 prepare stato stopi release E Video StreamSender F VideoStreamSender getLocalvideoPort setLocalvideoPort getRemoteAddress 4 setRemoteAddress getRemotevideoPort 4 amp setRemotevideoPort 4 getvideoFrameRate 4 setVideoFrameRate 4 getVideovvictho amp set vvideovidth getvideoHeight setvideoHeight 4 getOutputFormat 4 setOutputFormat
10. currently two constants defined in this class public static final int I LIKE IT FEEDBACK ID 0 public static final int I HATE IT FEEDBACK ID 1 Page 26 LiveTV Technical documentation Date 2010 01 15 These constants are the values of the bytes that will be sent to the server when the user selects I like it or I hate it options in the feedback menu The address of the remote server is currently defined as a constant in the FeedbackSupport class and is now set to the following value socket localhost 2222 In case the application runs on the emulator this is the address of the host computer on which the emulator runs When an application will be used with a real server this address will have to be replaced with the address of the server that will be used for receiving the feedback Page 27 LiveTV Technical documentation Date 2010 01 15 7 VLC with AMR support In this project VLC is used to relay the video and audio stream from the recorder phones to the viewer phones It is incorporated into the Studio application For each recorder a separate VLC server is launched which then receives the stream and relays it to the Darwin Streaming Server The main problem of the VLC is the lack of AMR support AMR is an audio codec designed by the 3GPP group and is used mostly for mobile phone audio streaming It is very light and requires low bandwidth Because of licensing issues VLC lacks support for
11. part will be about the non class elements of the application part of the Symbian standard template 3 1 High level OS classes These classes are used by the OS itself for launching the application Although the application it written in C it doesn t have the standard main Instead it has an E32MAIN which is used for application launching This method then runs the EikStart RunApplication method with a new application pointer as a parameter This parameter is of CRecorderApplication class which extends the CAknApplication class The later class is the basis for all Symbian applications and all user applications should extend this class The first class in this group is therefor the CRecorderApplication class During the creation of an object of this class a new object of CRecorderDocument class is created This class is the second of the high level OS classes used The purpose of this class is to create an AppUI object which will then be used for container creation Containers are used for graphical interface display The only purpose of this second class is therefor creation of AppUI The AppUT itself is part of the GUI classes 3 2 GUI classes The GUI itself is created through the GUI designer which is a part of Carbide c The design made through the GUI designer is then transfered into source code by the IDE itself The source code from the Designer is integrated in to a total of three classes which are e CRecorderAppUi e
12. was manually implemented because there is currently no support for handling integer preferences in the preference screen This preference was implemented by extending the existing preference EditTextPreference Part of the XML file that defines the preferences is listed hereafter lt xml version 1 0 encoding utf 8 gt lt PreferenceScreen xmlns android http schemas android com apk res android gt lt PreferenceCategory android title string preference category streaming gt lt CheckBoxPreference android key string preference stream video android title string preference stream video title gt lt CheckBoxPreference gt lt CheckBoxPreference android key string preference stream audio android title string preference stream audio title gt lt CheckBoxPreference gt lt CheckBoxPreference android key string preference exchange parameters android title string preference exchange parameters title gt lt CheckBoxPreference gt lt PreferenceCategory gt Page 11 LiveTV Technical documentation Date 2010 01 15 3 Symbian recorder This purpose of this document is to provide the necessary technical documentation regarding the recording application that was developed for Symbian based mobile phones The application was developed in Symbian C programming languages and therefor follows the basic ANSI C together with Symbian C modifications It has specific class connections which are bas
13. 6 FER LiveTV Technical Documentation Version 1 0 LiveTV Technical documentation Date 2010 01 15 Revision History 2010 01 14 0 01 Initial Draft Amer Clement Darko Dalibor Neven eljko Nima Doc No Page 2 LiveTV Technical documentation Date 2010 01 15 1 Introduction 1 1 Purpose of this document The purpose of this document is to provide technical details of software components that this project is made of 1 2 Document organization The document is organized as follows Section 1 ntroduction describes contents of this guide used documentation during developing process Section 2 Android recorder explains technical details about Android recorder application Section 3 Symbian recorder explains technical details about Symbian recorder application Section 4 Android player explains technical details about Android player application Section 5 Symbian player explains technical details about Symbian player application Section 6 Java player explains technical details about Java player application Section 7 VLC with AMR support explains how to add AMR audio codec support to VLC server Section 8 Streaming server explains technical details and configuration of streaming server Section 9 Studio application explains technical details about studio application 1 3 Intended Audience The intended audience is Project customer Project superv
14. AMR because FFMPEG which is used for audio video decoding lacks the support To enable the AMR support VLC recompilation was required This process is done in three separate parts which come after one another Those are 4 libamr nb and libamr wb compilation 5 FFMPEG compilation with AMR support 6 VLC compilation with newly compiled FFMPEG First the whole compilation process has to be explained before describing the details This project uses the Windows version of VLC In order to recompile the VLC there are two ways of doing it First is the native way on Windows using Cygwin or MinGW Second is recompilation on a Linux machine using 1586 mingw32msvc cross compiler GCC cross compiler can be found in the repository of various Linux distributions version used is from Ubuntu 9 10 Official VLC builds are created using cross compilation so this is the best choice In order to successfully recompile VLC additional libraries have to be added into the system VLC uses these libraries for various decoding muxing streaming etc These libraries can be manually compiled from source or they can be downloaded alredy compiled for a specific version of VLC The second package is called contribs package Contribs package already has its own version of FFMPEG which lacks support for AMR The process of VLC recompilation consists of recompiling FFMPEG with AMR support replacing the contribs version of FFMPEG with the recompiled one and then recompilin
15. Media API Java ME player uses the JSR 135 or Mobile Media API MMAPI to play the streamed content Functionalities of this API can be accessed through the Manager class that can be found in the javax microedition media package This class defined the static method createPlayer that can be used to create a player that will play any of the audio or video formats supported on a mobile phone This method receives a string that defines the location of the media that should be played This string should be in the URI syntax This allows for very easy playback of remote content To play any supported remote content a player needs to be created using createPlayer method with the URI of this content The createPlayer method returns a Player instance that can be used to control the playback of the media From this Player instance a VideoControl and VolumeControl objects can be obtained that can be used to resize the video that is being played and to control the volume of the audio Code reguired to create a player and start streaming is listed hereafter Player player Manager createPlayer videoLocation player prefetch player start First a new player is created After that prefetch is called that will buffer the media that will be played In the end the start method is called that will start the playback of the media The Player object can be in five different states Change from one state to another can be done by calling various me
16. SVN repository dated 20090212 This exact version has to be checked out of the repository The compiling will not go smoothly because some headers in libswscale have multiple definitions at two places This is a common problem and the necessary patch can be found on the Internet After the source code of the FFMPEG has been extracted into a target directory the compilation process begins First we have to run the configure script with a great number of parameters configure target os mingw32 enable memalign hack extra cflags I usr win32 include extra ldflags L usr win32 lib prefix usr win32 cross prefix i586 mingw32msvc enable libfaac enable libmp3lame enable postproc enable gpl enable libamr nb enable libamr wb enable nonfree disable debug disable shared After the configure script has finished we have to run the make command to start the compilation In case of multi core CPU the process can be accelerated using more cores for compilation make j 2 After the compilation is complete we have a working new version of FFMPEG Now we have to install the newly created FFMPEG libraries into the contribs The easiest way of doing this is by simply copying the libavcodec a and libavformat a files into the usr win32 lib directory This has proven successful The other way is to run the following command sudo make install libs This however could end up badly because it will install all FFMPEG librar
17. This data are taken from the AssemblyInfo cs file of the project 9 2 Connection authentication between the Studio and recorders Every recorder need to be authenticated on the Studio Application before start streaming The exchange starts from the recorder It contacts the Studio Application on the IP address and port that are specified in the settings It sends data through TCP protocol in the following format Username EventPassword Description Then if the username is unused and the password correct the studio application send back the video s port and audio s port like following videoport audioport Then the recorder is automatically added in the list of streams 9 2 1 ManageConnections This class allows all the management around new recorders It calculates the next couple audio and video of port listen for new recorder create event when a new one is added 9 2 2 NewRecorderEventArgs This class transfers the event and specially the information incoming from the recorder to the listbox of streams Page 33 LiveTV Technical documentation Date 2010 01 15 9 2 3 Recorder This class manages the TCP pipe between the recorder and the studio application It s here that the verification of the password s event and the username are done 9 3 Video Player The video player use libraries of VLC to play the different streams 9 3 1 Player This class is the player indeed There are functions like play stop mute
18. Uri parse url player setDataSource this uri player setDisplay holder player setAudioStreamType AudioManager STREAM MUSIC player setOnPreparedListener this player prepareAsync player setOnBufferingUpdateListener this player setOnCompletionListener this address setText Yes catch Throwable t Log e TAG Exception in media prep t goBlooey t Page 20 LiveTV Technical documentation Date 2010 01 15 There are also some other methods in this class for handling OS operation which are note explained 4 2 URLHistory In this class there are two methods for saving URLs and loading saved ones to textbox void save Writer out throws JSONException IOException JSONStringer json new JSONStringer object for HistoryItem h spareCopy h emit json out write json endObject toString void load String rawJSON throws JSONException JSONObject json new JSONObject rawJSON for Iterator i json keys i hasNext String key i next toString HistoryItem h new HistoryItem key json getint key spareCopy add h add h 4 3 Historyltem class In this class there are two public members url and count and two constructors and one method for converting to string format String url null int count 1 HistoryItem String url lanis vrelu izbi Bien Sercakaej Well stigic Tobe 4 ctalneissuesta
19. arting a new Symbian project and are used as a template Other than them an additional class is added that displays the recorder viewfinder CRecorderViewfinder There are two ways of displaying a viewfinder to the screen First is using bitmap images which are projected on the screen The second is using direct feed from the camera The first method produces flicker and is not the best possible but all phones support it earlier versions of Symbian The second method is much better and gives a slick and smooth viewfinder but has been present only from the 3 2 edition of Symbian OS Therefor those two methods have to be interchanged regarding the functionality of the phone A simple if else solves this if iFinderDirectL CCoeEnv coeEnv CCoeEnv Static iCamera gt StartViewFinderDirectL coeEnv gt WsSession coeEnv gt ScreenDevice DrawableWindow rect else ty Start vew stsianclaie Oa rotcio ING JI ZE Concari tekle ira SLze iCamera gt StartViewFinderBitmapsL finderSize Calculate position for finder bitmaps centered on component iFinderPosition is the top left coordinate for bitmap iFinderPosition rect iTl iFinderPosition iX rect Size iWidth finderSize iWidth 2 iFinderPosition iY rect Size iHeight finderSize iHeight 2 Other than this the viewfinder class is used for starting the camera Camera is started in a specific asynchronous way This pr
20. e 2010 01 15 maintains its raw file format and is read as a stream of bytes using AssetManager class 2 2 Streaming This chapter describes the Android classes used for recording and a way in which streaming was accomplished using these classes Android SDK defines two classes that can be used for recording audio or video content AudioRecord and MediaRecorder AudioRecord class can be used to record raw audio while MediaRecorder can be used to record audio and video content that can be encoded using a number of different encoders Neither of those classes directly supports streaming AudioRecord can be used to get the raw audio data and after that this data can be sent over a network using some streaming protocol like RTP Problem with the AudioRecord class is that the data must be encoded manually before sending MediaRecorder class has the data encoding support but this class is intended only for storing the recorded data in the phone or in other words it isn t intended for streaming recorded data to the remote server This problem becomes apparent when setting the output location for the recorded data The output location can be defined in two ways with a path to the output file or with a file descriptor Saving data in a file an reading it afterwards in order to stream it over the network would be very inefficient because accessing memory is a lot faster than accessing a file on the disk Another problem is that it may not be possibl
21. e background for an indefinite period of time 3 Broadcast receivers receive and react to broadcast announcements 4 Content providers make a specific set of the application s data available to other applications Recording application provides a user interface for streaming video and audio content to a remote server Activities are the only component that deals with user interface and because of that this application is based on activities Some basic aspects of the Android activities are described in the following text An activity has essentially three states H it is active or running when it is in the foreground of the screen it is paused if it has lost focus but is still visible to the user it is stopped if it is completely obscured by another activity If an activity is paused or stopped the system can drop it from memory either by asking it to finish calling its finish method or simply killing its process When it is displayed again to the user it must be completely restarted and restored to its previous state This means that the application state must be saved every time the application is paused and restored every time the application is resumed As an activity transitions from state to state it is notified of the change by calls to the following protected methods void onCreate Bundle savedInstanceState void onStart void onRestart void onResume void onPause void onStop Page 4
22. e to read from a file while writing to the same file This means that the recording would have to be done in stages Recorder would record in one file for some time then it would close this file and continue recording in another file so that the first file could be read and streamed over the network This switch would be repeated in very short periods of time so that it would look like the recording is continuous But in the end both of these problems would probably cause substantial delay in the streamed content Fortunately there is a better solution to these problems Android is based on the Linux and Linux is based on files almost everything on Linux is a file including a socket This allows us to get a file descriptor from a socket and give this to the MediaRecorder as an output file That way MediaRecorder would write to a socket and everything that is being recorder would be sent through that socket to some remote server Using this solution we can send everything that is recorded to the server Next problem is that some streaming protocol should be used so the server can understand what it receives We decided to use RTP protocol for this But this approach also introduces some new problems Next paragraphs describe this problems and their solutions in more detail First problem was that we needed to get the recorded data before it is sent to the remote server This can easily be solved by implementing a server on a mobile phone This wa
23. eX plugin exposed by VLC s SDK and is used to relay the output stream coming from PC Studio to the DSS server as an RTP stream The ActiveX plugin is integrated in the PC Studio application embedded inside a wrapper class named DSSRelay Two functions are implemented in this class to relay either a live stream coming from Mobile recorder or an advertisement video VLC s ActiveX object is set up hardcoded to transmit the output RTP stream to the local IP address assuming that the DSS server is installed and running on the same machine server The ports used are 1260 for video and 1262 for audio 8 2 Darwin Streaming Server DSS Once a desired stream is selected for broadcast in the PC Studio there needs to be a mechanism to broadcast the chosen stream For this purpose Apple s open source Darwin Streaming Server was selected as it uses standard protocol for broadcasting i e RTSP real time streaming protocol RTSP is widely used to broadcast videos and live media through internet to mobile and desktop viewers Another reason to use DSS instead of other streaming servers such as Real Media Server or Helix streaming server which is the open source version is that it is possible to use it in load balancing mode i e form a cluster of DSS instances which can share the load if the number of viewers increases in future DSS has been configured to receive an RTP stream and broadcast it to the mobile and desktop viewers over the RTSP protoc
24. ects responsible for content streaming This activity first loads user preferences and initializes the objects responsible for streaming based on these preferences After that a user can start and stop the streaming via available menu options Recorder activity is also responsible for parameters exchange with the server If this exchange is activated in the settings it will be done every time when the user attempts to initiate the streaming process The client application sends username password and a description of the event that will be recorded to the server and the server should respond with the audio and video ports to which the corresponding streams should be sent In case of any errors during this exchange the client will display the errors messages to the user and will fall back to the parameters used in the previous session 2 6 Settings activity Settings activity allows the user to view and modify different settings that control various streaming parameters Android SDK defines classes that can be used for preference handling Preferences can be defined in two ways by creating a preferences xml file or by defining the preferences in the code We used the XML file approach Three types of preferences were used in this application CheckBoxPreference EditTextPreference and EditIntegerPreference Preferences were grouped using categories CheckBoxPreference and EditTextPreference are built in Android classes but the EditIntegerPreference
25. ecute the code within the run method when the streaming is started or in other words when the start method gets called This thread is stopped when the stop method gets called VideoStreamSender AudioStreamSender and RawAudioStreamSender can be used to easily implement support for streaming using different codecs Classes that extend those classes should define the code that will process the recorded data and sent it to a remote server When extending VideoStreamSender or AudioStreamSender the data is read using the local socket and when extending RawAudioStreamSender the data is read from the AudioRecord object Variables for accessing those objects are defined as protected so they are accessible from the subclasses VideoStreamSender AudioStreamSender and RawAudioStreamSender also define getter and setter methods for all of the important parameters that can be used to define audio or video quality codecs and Page 8 LiveTV Technical documentation Date 2010 01 15 information about remote endpoint where the data will be sent In the end three classes are defined that extend abstract classes from previous paragraph and define specific codec streaming logic These are RtpH263VideoStreamSender RtpAMRAudioStreamSender and RtpG711AudioStreamSender These classes define the code that reads the recorded data converts it in the format required for streaming and sends properly formatted data to the remote server The classes that implement
26. ed on the standard Symbian template Unlike standard C programs that start with a normal main Symbian applications have a specific class hierarchy It is similar to MVC model view controller in other programming languages but without the model The structure can be divided into three groups 1 Classes that communicate with Symbian OS these classes are part of the standard template and should not be changed They provide the necessary function to start the application switch the views and control the memory stack These classes will not be described into detail 2 Classes that provide the GUI these classes are also part of the standard template but are upgraded and changed during the GUI development Carbide c IDE for development provides a graphical variant of GUI development Developer adds GUI components into the design which are then transformed into source code and added to these classes Along with these classes will be the UI design file 3 Classes that provide the needed functionality these classes are entirely made by the developer They provide the controller part of the MVC In this case they provide the recording and streaming part of the application as well as the RTP wrapper class Without this the application would only consist from the graphical interface These classes will therefor be described in detail The documentation will also be divided in these three groups with the later being in more detail The last
27. formats which can be streamed on the phone and prints the results VideoCanvas defines all of the functionalities that deal with the streaming process VideoCanvas class extends the Canvas class that is a GUI component and can be used to draw on it This enables the VideoCanvas to draw the video that is being played on the underlying Canvas implementation VideoCanvas defines the methods for resizing the video muting the audio increase and decrease the volume VideoCanvas also defines the playVideo and stopVideo methods that are used to start and stop the playback of the media content The playVideo method starts the playback in another thread because the Player buffers some of the media before the playback starts This can take some time so it is done is separate thread so that the application would remain responsive during this time AlertSupport class is used for displaying the error or information messages to the user This class is used in all other classes to allow for centralized alert management AlertSupport defines two methods alertError and alertInfo The first method displays an error message and the second one displays an informational message to the user FeedbackSupport class is used to send the feedback message to the server This class defines only one method sendFeedback This method creates a socket to the remote server and sends the feedback using this socket The feedback information is sent by using only one byte There are
28. g VLC The project uses VLC version 0 9 9a Contribs that are used for this version are 0 9 9 7 1 Libamr nb and libamr wb compilation In order to integrate AMR into FFMPEG first the AMR libraries have to be compiled The source code of the libraries can be downloaded from the following website http www penguin cz utx amr The needed packages are e amrnb 7 0 0 2 tar bz2 e amrwb 7 0 0 3 rat bz2 After these are downloaded they have to be configured using the usr win32 prefix We choose this path because we previously extracted the contents of contribs package into this directory This way we will add the AMR libraries directly into the contribs libraries and other contribs files After configuring and compiling with make the libraries and headers are installed into the contribs directory using make install libs make install headers The same is done for both libamr nb and libamr wb First is the narrow band and second is the wide band Page 28 LiveTV Technical documentation Date 2010 01 15 version of the codec 7 2 FFMPEG compilation with AMR support After compiling AMR libraries and headers FFMPEG has to be recompiled with this newly added AMR support It is very important to find out the exact version of FFMPEG that is used in the contribs package After carefully examining the source code and the MINOR and MAJOR version strings it was concluded that the contribs use the r17458 from the FFMPEG
29. ies and not just the libavcodec which has the AMR support 7 3 VLC compilation with newly compiled FFMPEG After we have compiled FFMPEG and copied the libraries now we have to recompile the VLC against the newly compiled FFMPEG to enable AMR support The VLC version that is used is 0 9 9a After we have extracted the VLC source code into the target directory we have to run the following configure script bootstrap Page 29 LiveTV Technical documentation Date 2010 01 15 PATH usr win32 bin SPATH PKG_CONFI G LIBDIR lt usr win32 lib pkgconfig CPPFLAGS lt I usr win32 include I usr win32 include ebml LDFLAGS L usr win32 lib CC i586 mingw32msvc gcc CXX i586 mingw32msvc g configure target i586 minwg32msvc host lt i586 mingw32msvc build lt i386 linux disable gtk enable nls enable sdl with sdl config path usr win32 bin enable ffmpeg with ffmpeg mp3lame with ffmpeg faac with ffmpeg zlib enable faad enable flac enable theora with wx config path usr win32 bin with freetype config path lt usr win32 bin with fribidi config path lt usr win32 bin enable live555 with live555 tree lt usr win32 live com enable caca with caca config path lt usr win32 bin with xml2 config path lt usr win32 bin with dvdnav config path lt usr win32 bin disable cddax disable vcdx enable goom enable twolame enable dvdread enable debug disable zvbi The configure consists of two
30. isor Project team members Users 1 4 Scope 1 5 Definitions and acronyms 1 5 1 Definitions 1 5 2 Acronyms and abbreviations Acronym or cu Model view controller Graphical user interface Intergrated development environment FFMPEG Complete cross platform solution to record convert and stream audio and video Page 3 Technical documentation Date 2010 01 15 Rm Real time Transport Protocol 1 6 References Installation manual User manual 2 Android recorder 2 1 Android operating system Android is a mobile operating system running on the Linux kernel It allows developers to write managed code in Java programming language controlling the device via Java libraries developed by Google The central feature of Android operating system is that it allows an application to reuse other application s components provided those applications permit it For this to work the system must be able to start an application process when any part of it are needed and instantiate the Java classes for that part Therefore unlike the applications on most other operating systems Android applications don t have a single entry point for everything in the application no main function for example Instead they are composed of components that the system can instantiate and run as needed There are four types of those components 1 Activities present a visual user interface for one focused endeavor 2 Services run in th
31. l documentation Date 2010 01 15 2 4 2 G711 audio G711 encoder used in this project is developed by Jutta Degener and Carsten Bormann from Technische Universitaet Berlin and it is the same encoder that is used in the SipDroid open source project RtpG711AudioStreamSender reads the data from AudioRecorder object sends this data to the G711 encoder that encodes this data using G711 codec This encoded data is afterwards sent using RTP protocol 2 4 3 AMR audio AMR audio frames are of constant length so it is easier to read them than H263 frames Before the audio data there are some 3GPP headers RtpAMRAudioStreamSender first skips all of the 3GPP headers and then just reads the audio frame from the input socket After the frame is read required headers are inserted before the frame and the frame is sent using the RTP protocol Current implementation of this class has some problems that weren t resolved When streaming content to the VLC player VLC prints error PTS is out of range When manually inspecting sent data using Wireshark trace it seams that the Android recorder sends the correct data so it is not currently clear whether this is a bug in the VLC or in the Android recorder This should be examined in more detail 2 5 Recorder activity The recorder activity is the activity that is displayed to the user when the application is started This activity defines the graphical user interface of the application and controls the obj
32. le menu button presses For each option in the menu exist a method which handles the event The incoming event is switched in the code switch aCommand code to dispatch to the AknView s menu and CBA commands case ERecorderContainerViewRecordMenuItemCommand commandHandled HandleRecordMenultemSelectedL aCommand break case ERecorderContainerViewSet IP AddressMenultemCommand commandHandled HandleSet IP AddressMenultemSelectedL aCommand break case ERecorderContainerViewSet PortsMenultemCommand commandHandled HandleSet PortsMenultemSelectedL aCommand break case ERecorderContainerViewCredentialsMenuItemCommand commandHandled HandleCredentialsMenultemSelectedL aCommand break case ERecorderContainerViewResolutionMenultemCommand commandHandled HandleResolutionMenuItemSelectedL aCommand break case ERecorderContainerViewFrame RateMenuItemCommand commandHandled HandleFrame RateMenultemSelectedL aCommand break default break Each event is then handled in its own method Most of this events are for settings and preferences and are used to change the settings When a user clicks on a button that is used for that a guery dialogs pops up and asks the user for new settings This guery dialogs are also created by the GUI Designer and are just extended so that they save the new settings in a variable that keeps that setting for instance frame rate is saved in a variable in CRecorder Engine class
33. ll be described later After that we can safely start the recording Recording is also an asynchronous process which consists of Prepare and Record method calls OpenL aAudioType aVideoMimeType TCCMRVideoCodingOptions options options iMinRandomAccessPeriodInSeconds 10 options iSyncIntervalInPicture 1 Page 15 LiveTV Technical documentation Date 2010 01 15 iRecorder gt SetVideoCodingOptionsL options iSink gt iRTPEngine gt StartRTPConnectionL destIP Address destPort username password iState EStatePreparing iRecorder gt PrepareL As it was said the CRecorderSink class is used for receiving the recorded frames of audio and video These frames have to be encapsulated in RTP and codec headers and then transmitted via RTP class object The RTP class object is created during the construction of the Sink object CRecorderSink CRecorderSink iVideoBufferCounter 0 iVideoDataLength 0 iAudioBufferCounter 0 iAudioDataLength 0 iRTPEngine CRecorderRTP NewL iRTPEngine gt EstablishConnectionL This also provides a query dialog which gives the user an option to choose which network to use will be described later The sole purpose of this class is to receive frames and send them via RTP to the server This is done in the WriteBufferL method First we have to find out whether it is an audio or a video frame aie GUE yore shWalcloeiCer
34. n application which launches Symbians default player which is Real Player so this is very simple software and does not need very long documentation The only code that is necessary to be explained is the HandlePlayMenultemSelectedL function in CPlayerContainerView class Other classes are Symbian s base template classes which are explained in Symbian recorder documents TBool CPlayer4ContainerView HandlePlayMenultemSelectedL TInt aCommand aCommand 0 RApaLsSession session User LeavelfError session Connect CleanupClosePushL session Wap Browser s constants UId const TInt KWmlBrowserUid 268458558 const TInt KWmlBrowserUid 0x10008D39 TUid uid TUid Uid KWmlBrowserUid TBuf lt 256 gt filename rtsp filename Copy L rtsp www hooraytv net livetv sdp TFileName aFileName filename Runs the default application using the UID TThreadid threadId User LeavelfError session Connect connect to AppArc server session StartDocument aFileName uid threadId session Close CleanupStack PopAndDestroy session return ETrue ESE In this code we provide URL address of our server which is streaming video and then we ask operating system to open this URL Since it is address of video file automatically it lunches to default player which is Real Player Page 24 LiveTV Technical documentation Date 2010 01 15 6 Java player 6 1 Mobile
35. ocess is stared with the Reserve command on the CCamera class After this method is completed it asynchronously invokes a method in the viewfinder class which then runs the Prepare method To be able to do this the viewfinder class must extend the MCameraObserver class Once the camera object is created it can be used in other parts of the application which require the camera such as recording via the camera handler The camera has to be released before that TInt CRecorderViewfinder CameraHandle if iFinderDirectL iCamera gt StopViewFinder return iCamera gt Handle Page 14 LiveTV Technical documentation Date 2010 01 15 3 3 Recording classes This classes are entirely developer based In other words they are not included in the template but have been developed for the recording process Those classes are e CRecorderEngine e CRecorder ink e CRecorderRTP The base class is the CRecorderEngine class It is created during the activation of the viewfinder The constructor of this class starts with the creation of a CCMRMediaRecorder object that is used for recording and is part of the MediaRecorder API of the Symbian OS A new CRecorderSink is also created but that will be explained later After that the predefined settings are loaded iCameraHandle lt aCameraHandle iRecorder CCMRMediaRecorder NewL iSink lt new ELeave CRecorderSink TBuf16 lt 16 gt IPaddress IPCs
36. ol It runs as a background service and doesn t reguire user interaction Only one SDP file is placed in the Movies folder of DSS which describes the relay configuration of the stream coming from PC Studio 8 3 DSS and VLC Integration The Streaming Server DSS and VLC are tightly integrated with each other forming one relay and distribution server i e the Streaming Server in this project DSS is preconfigured to broadcast the stream coming from VLC ActiveX plugin in PC Studio by the use of an SDP Session Description Protocol file whose contents are given below Livetv sdp v 0 o 14913302681658377371 14913302681658377371 IN IP4 lap 00365 Page 31 LiveTV Technical documentation Date 2010 01 15 s lt LiveTV i N A c IN IP4 127 0 0 1 t 0 0 a tool vlc 0 9 9 a recvonly a type broadcast a charset UTF 8 m audio 1262 RTP AVP 96 b RR 0 a rtpmap 96 AMR 8000 a fmtp 96 octet align 1 m video 1260 RTP AVP 97 b RR 0 a rtpmap 97 H263 1998 90000 This file is placed in the Movies folder of DSS i e C Program Files Darwin Streaming Server Movies and the access URL of the final broadcasted stream to be used by the desktop and mobile client players is rtsp www hoorayty net livetv sdp assuming that the streaming server is running on hooraytv net host Furthermore the DSS and PC Studio should be running on the same server to decrease any intermediate streaming delays and to avoid any introduction of addi
37. pabilities are available if you aren t a licensed Symbian developer The recorder application uses the following capabilities e NetworkServices e UserEnvironment First capability is needed for Internet access and the second for camera and microphone access It was already said that the menu creation is done using other files in the project When we design the UI in the GUI Designer the IDE creates those files These are rss files The project has three such files Recorder rss Recorder reg rss and RecorderContainer rssi The menus are in the later file This part of the file defines the main menu RESOURCE MENU PANE r recorder container menu panel menu pan items MENU_ITEM command ERecorderContainerViewRecordMenultemCommand txt STR RecorderContainerView 5 MENU_ITEM cascade r recorder container menu_pane2 txt STR RecorderContainerView 7 Other than that a developer should get to know himself with Symbian development before analyzing this project This can be done using user guides for Symbian development or various books Page 18 LiveTV Technical documentation Date 2010 01 15 4 Android player Purpose of this document is to provide the necessary technical documentation regarding the player application that was developed for Android mobile phones The application is consist of six classes which are going to be explained in following section
38. parts running bootstrap VLC internal and running configure After running bootstrap we have to manually edit the newly created configure file and add the following lines somwhere line 1919 in the file add extralibs libamrnb lm libamrwb lm After that we can run the configure seript with the parameters above After the configure is completed we start the compilation make j 2 After the VLC in successfully compiled we create the Zip package with the following command make package win32 zip After that we have a working copy of VLC with AMR support Page 30 LiveTV Technical documentation Date 2010 01 15 8 Streaming server The purpose of this document is to provide the necessary technical documentation regarding the streaming server that receives live stream from PC Studio and broadcasts it to mobile and desktop viewers The streaming server is a combination of Apple s open source Darwin Streaming Server DSS and VideoLAN VLC VLC is integrated in PC Studio and it streams output stream to DSS via RTP streaming DSS then relays the stream as a broadcast to mobile and desktop viewer clients This document is divided into four parts the VLC component DSS component and how they are integrated Lastly the Installation and User guide follows 8 1 VideoLAN VLC VideoLAN is an excellent tool for audio and video playback and streaming It has a plugin oriented architecture and in this part of the project Activ
39. s can be used in order to receive UDP message from any client Similar to Socket Client class this class is not getting used in project right now Sequence of code is very similar to Socket Client class but instead of sending package we are receiving package public vo rd sun try 4 Retrieve the ServerName InetAddress serverAddr InetAddress getByName SERVERIP ROG CN WUDDEN Wiss Sexewer Cone cin oz Create new UDP Socket DatagramSocket socket new DatagramSocket SERVERPORT serverAddr By magic we know how much data will be waiting for us byte buf new byte 17 Prepare a UDP Packet that can contain the data we want to receive DatagramPacket packet new DatagramPacket buf buf length oce RUDE MIS MIRE Go valna oz Receive the UDP Packet socket receive packet Log d UDP S Received new String packet getData In g ograd MUIR Wisse SORE DANENA Page 22 LiveTV Technical documentation Date 2010 01 15 socket close o gms LUD PA ea Sen ve r COSE dr catch Exception e Bogme upka VS Senge Mn so 4 163 Page 23 LiveTV Technical documentation Date 2010 01 15 5 Symbian player Purpose of this document is to provide necessary information about symbian player The application was developed in Symbian C programming languages and follows symbian template This application is a
40. sageSlots User LeavelfError iConnection Open iSocketServer KConnectionTypeDefault TCommDbConnPref prefs prefs SetDialogPreference ECommDbDialogPrefPrompt prefs SetDirection ECommDbConnectionDirectionOutgoing User LeavelfError iConnection Start prefs iConnState ETrue Page 16 LiveTV Date 2010 01 15 Technical documentation return ETrue RTP connection creation is invoked during the start of the recording with the StartRTPConnectionL method Before we create the connection the application must communicate with the Studio to receive audio and video ports that will be used for the transfer After that two separate RTP connections are created The connections share the same Internet connection Open RTP session aError iRtpSessionVideo gt OpenL iParam NULL amp iSocketServer amp iConnection if aError KErrNone LOGNUM1 TOFILE CRecorderRTP StartRTPConnectionL error at iRtpSession gt OpenL d aError aError iRtpSessionAudio gt OpenL iParam NULL amp iSocketServer amp iConnection if aError lt KErrNone LOGNUM1 TOFILE CRecorderRTP StartRTPConnectionL error at iRtpSession gt OpenL Sd aError After this part standard parameters for each connection are set according to RTP API documentation The stream ID is used later when transferring the video and audio frames iTransmitS
41. slSe else if aBuffer gt Type iAudioCodec The code for video and audio is different The video used is h263 and the audio is AMR Both of these have to be encapsulated according to the RFC documents which deal the transfer of those formats via RTP These are RFC4629 for h263 and RFC4867 for AMR The code for encapsulating won t be discussed into detail here What needs to be mentioned is that there are two levels of encapsulation First is the RTP header which is used for RTP transfer It has values such as payload type 103 for video and 108 for audio and timestamp More important is the inner header which is used for demuxing the content at the server These headers are discussed in the RFCs It is important to keep each RTP packet under the MTU size Video packets can be bigger that MTU In that case the video frame has to be divided into two packets and this procedure has to be marked accordingly in the header flags Symbian provides the necessary API for RTP transfer This API is also used in the CRecorderRTP class It is used twice In other words separate RTP connections are created for audio and video Before constructing the RTP connections an Internet connection has to be created This connection will be used throughout the project For video and audio transfer and for communication with the studio TBool CRecorderRTP EstablishConnectionL User LeavelfError iSocketServer Connect KESockDefaultMes
42. sradle oleraelle this count count Dolie Surre cose return url void emit JSONStringer json throws JSONException json key url value count 4 4 TappableSurfaceView In this class we just handle touch and tap events Page 21 LiveTV Technical documentation Date 2010 01 15 4 5 SocketClient In this class we send message over UDP connection This is implemented in order to send feedback to studio application In the run method we define one socket and then put information into a packet and send it over the socket Moreover they are some lines of code which are writing log in order to test the system public void run 4 try 4 Retrieve the ServerNam InetAddress serverAddr InetAddress getByName SERVERIP Io GREGA DESNA Wes Client Conicet sa Ne Create new UDP Socket DatagramSocket socket new DatagramSocket Prepare some data to be sent byte buf Message getBytes Create UDP packet with data amp destination url port DatagramPacket packet lt new DatagramPacket buf buf length serverAddr SERVERPORT HOG CEUDEN Wes Seneng VV Sr new Sesimej louue ee Send out the packet socket send packet ho Gece MUD PUG Cm Senin og RU DEM Cilie Done socket close POG CND o Mele nek Clossch 4A catch Exception e 1 oce UMU DEDE es Cllaieinte lnreiore 5 4 6 SocketServer This clas
43. t using RTP protocol some additional headers have to be added before the raw video and Page 7 LiveTV Technical documentation Date 2010 01 15 audio frames These headers are described in detail in RFC4629 for H263 codec and in RFC4867 for AMR codec All data manipulations required before sending this data using RTP protocol is done by the server on the mobile phone This server extracts the raw recorded frames adds required headers forms the RTP packet and sends it to the remote server The final problem was that RTP is not implemented in Android so it should be implemented manually To avoid doing this we reused RTP protocol implementation used in SipDroid open source project 2 3 Recording application This chapter describes the developed application for Android based mobile phones Recording application consists of two activities Main activity is the Recorder activity that controls the recording process and defines the main user interface The second activity is the Settings activity that can be used to change different settings of the application Actual audio and video content recording is done using the classes available in the Android SDK but SDK doesn t support audio or video streaming Streaming support is implemented as part of this project Some classes used for streaming were originally defined in SipDroid open source project or some of the other open source projects which SipDroid project uses 2 4 Streaming classes
44. the CLOSED state the Player has released most of its resources and must not be used again Page 25 LiveTV Technical documentation Date 2010 01 15 6 2 Implementation Implementation of the Java ME player consists of four classes LiveTVPlayer VideoCanvas AlertSupport and FeedbackSupport These classes will be explained in more detail in this chapter The following figure shows the class diagram with the listed classes FE LiveTVPlayer rana ElvideoCanvas Operations public VideoCanvas AlertSupport alertSupport public void setAlertSupport AlertSupport alertSupport protected void sizeChanged int w int h private void resizeVideo int width int height public void playVideo String videoLocation public boolean stopVideo public void goToFullScreen public int getVolumeLevel public void setVolumeLevel int level A public void volumeUp public void volumeDown FE FeedbackSupport Operations public FeedbackSupport AlertSupport alertSupport Operations public AlertSupport MIDlet midlet public void alertError String message Figure 4 Java ME player classes LiveTVPlayer is the main class of this application This class defines the graphical user interface of the application and uses functionalities of the other of the listed classes to implement streaming functionalities LiveTVPlayer also defines the checkMMSupport that checks for the supported media
45. thods defined in the Player class These states and the methods that can be used to change the player s state are shown in the following figure CLOSED close close UNREALIZED REALIZED PREFETCHED deallocate deallocate stopi Figure 3 The Player s five states and the state transition methods States in which an instance of the Player class can be are described in the following text e UNREALIZED this is the player s initial state an UNREALIZED player does not have enough information to acguire all the resources it needs to function e REALIZED if the player is in the REALIZED state it has obtained the information required to acquire the media resources Realizing a Player can be a resource and time consuming process e PREFETCHED once REALIZED a Player may still need to perform a number of time consuming tasks before it is ready to be started For example it may need to acquire scarce or exclusive resources fill buffers with media data or perform other start up processing Calling prefetch on the Player carries out these tasks e STARTED once prefetched a Player can enter the STARTED state by calling the start method A STARTED Player means the Player is running and processing data A Player returns to the PREFETCHED state when it stops because the stop method was invoked it has reached the end of the media or its stop time CLOSED calling close on the Player puts it in the CLOSED state In
46. tional bottlenecks in the system More details on installation are presented as a guide in the next section of this document which is then followed by the Usage guide Page 32 LiveTV Technical documentation Date 2010 01 15 9 Studio Application The purpose of this document is to provide the necessary technical documentation regarding the studio application that receives streams from recorder mobile and send it to the broadcast server DSS The Studio application is divided into four different parts o User Interface AboutBoxLiveTV StudioApplication Settings o Connection authentication between the Studio and recorders ManageConnections NewRecorderEventArgs NewRecorderEventHandler Recorder o Video player Player VideoPlayer VideoPlayerManager o LibVLC wrapper 9 1 User Interface 9 1 1 StudioApplication class This class is the main class for the User Interface It was generated automatically by the Visual Studio designer All the events of it are also managed into it There is also a function that forces to load the dll of vle and allow watching faster the first stream played There are also some functions that manage the new recorder and automatically populate the stream list 9 1 2 Settings This class allows to visualize and specify the settings of the system All of them can be modified 9 1 3 AboutBoxLiveTV This class is showing some information about the project like the member and a description
47. treamIdVideo iRtpSessionVideo gt CreateTransmitStreamL iRtpIdVideo aTransmitParams iSsrcIdVideo iTransmitStreamIdAudio iRtpSessionAudio gt CreateTransmitStreamL iRtpIdAudio aTransmitParams iSsrcIdAudio RTP packets are sent in the SendRtpPacketL method They are sent differently if a video or an audio packet is sent if AV iAudioTimeStamp aTimeStamp iSendHeader iTimestamp iAudioTimeStamp iSendHeader iPayloadType 108 rror iRtpSessionAudio gt SendRtpPacket iTransmitStreamIdAudio iSendHeader aBuffer else iVideoTimeStamp aTimeStamp iSendHeader iTimestamp iVideoTimeStamp iSendHeader iPayloadType 103 rror iRtpSessionVideo gt SendRtpPacket iTransmitStreamIdVideo iSendHeader aBuffer Since the application should never receive RTP packets this method is empty If an RTP packets arrives it invokes an error Page 17 LiveTV Technical documentation Date 2010 01 15 3 4 Non class elements There are a number of non class elements in a Symbian C project but only the most important will be described here The Recorder mmp file is used to define the basic information about the application such as stack and heap size libraries used Symbian applications have a thing called capabilities This marks which permissions will the application have on the phone The permissions range from Internet access to shutter key access Only some ca
48. xtView findViewById R id address address addTextChangedListener addressChangeWatcher history new URLHistory this android R layout simple dropdown item lline For setting default addres address setText http www inventa com au mpeg4 2056kbps176X144PAL mpg address setText rtsp stream zoovision com zootoones merry melodi Smerneshwharer 59 try File historyFile new File getFilesDir HISTORY FILE if historyFile exists Page 19 LiveTV Technical documentation Date 2010 01 15 BufferedReader in lt new BufferedReader new InputStreamReader openFileInput HISTORY FILE S raise tr StringBuilder buf new StringBuilder while str in readLine null buf append str buf append n in close history load buf toString catch Throwable t Log e TAG Exception in loading history t goBlooey t address setAdapter history There is also method for building feedback menu which is onCreateOptionsMenu public boolean onCreateOptionsMenu Menu menu menu add 0 0 0 Like menu add 0 1 0 Hate return true The play method is responsible of playing video using mediaPlayer class private void playVideo String url Tay dl media setEnabled false if player null player new MediaPlayer player setScreenOnWhilePlaying true else player stop player reset Uri uri
49. y we could send the data to the server on a mobile phone modify it in any way necessary and then resend it to the actual remote server To achieve this the data was sent through a local socket to the local server socket A thread read from this local server socket made reguired modifications to the data and sent it to the remote server using another socket The second problem was that Android records either in 3GPP or MP4 format neither of which were good for sending using the RTP protocol These files contain some additional data besides the actual recorded audio and or video frames We decided to record in 3GPP file format using H263 video codec and G711 or AMR codecs for audio G711 codec is implemented in SipDroid project using AudioRecord class and we reused their implementation for recording and encoding recorded data AMR and H263 were implemented using MediaRecorder class 3GPP file format consists of atoms where each atom starts with its size There are different kinds of atoms in a file but mdat atom is particularly interesting because it contains the raw recorded frames which are necessary for RTP streaming In order to extract this raw data all other 3GPP atoms need to be skipped Once the mdat atom is found and skipped the raw data will follow until the recording stops Additionally the data obtained in this way cannot be directly sent using RTP According to the RFC documents which deal with the transfer of the H263 and AMR conten
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