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Symbian3/SDK/Source/GUID-D038D77F-A6B8-5A18-8978-4981AE8D0F35.dita
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     7     Nokia Corporation - initial contribution.
 
     7     Nokia Corporation - initial contribution.
 
     8 Contributors: 
     8 Contributors: 
     9 -->
 
     9 -->
 
    10 <!DOCTYPE task
 
    10 <!DOCTYPE task
 
    11   PUBLIC "-//OASIS//DTD DITA Task//EN" "task.dtd">
 
    11   PUBLIC "-//OASIS//DTD DITA Task//EN" "task.dtd">
 
    12 <task xml:lang="en" id="GUID-D038D77F-A6B8-5A18-8978-4981AE8D0F35"><title> Using the Encoded H264 Video Frames to Capture Video</title><shortdesc>This topic describes how to use the encoded H264 video frames in the Ecam video capture function to capture the video data. </shortdesc><prolog><metadata><keywords/></metadata></prolog><taskbody> <prereq id="GUID-E8812B46-29C5-56D8-9658-B0B03D601B2C"><p>You need to be familiar with the <xref href="GUID-F690DAC8-688B-5BD7-88DF-0CB3D4ACDCFF.dita">Capturing Video</xref> tutorial. </p> </prereq> <context id="GUID-3B0CFDEE-297B-56D0-A73A-B45C2E8C550C"><p>The H264 video encoder provides a new, high quality video data encoding format for Ecam. Ecam allows the device to capture video frames which are encoded in the H264 format. The Ecam video capture function supports the H264 video capture format by default. You can select the H264 video capture format when preparing video capture. </p> </context> <steps id="GUID-459D27D6-C0F7-5B94-8E34-C250AF3B6B77"><step id="GUID-4A02BBE6-CDAE-5FD1-8F05-30867627197B"><cmd/><stepxmp>Call the <xref href="GUID-021C509B-C821-3401-B2F4-DE7F52BB16D4.dita"><apiname>CCameraVideoCaptureControl::NewL()</apiname></xref> function to create an object that maps the exported call to an internal object of the <xref href="GUID-021C509B-C821-3401-B2F4-DE7F52BB16D4.dita"><apiname>MCameraVideoCaptureControl</apiname></xref> function. </stepxmp> </step> <step id="GUID-480FA9CE-DC0A-5586-A4C2-A2DEB1D7BCEE"><cmd/><info>Pass a handle to the <xref href="GUID-021C509B-C821-3401-B2F4-DE7F52BB16D4.dita"><apiname>MCameraVideoCaptureControl</apiname></xref> function. This implementation creates a handle to the <xref href="GUID-021C509B-C821-3401-B2F4-DE7F52BB16D4.dita"><apiname>CCameraVideoCaptureControl</apiname></xref> object by the active <xref href="GUID-021C509B-C821-3401-B2F4-DE7F52BB16D4.dita"><apiname>CCamera</apiname></xref> during the construction phase. </info> <info>The <codeph>CCameraVideoCaptureControl</codeph> object makes an internal call to the <xref href="GUID-021C509B-C821-3401-B2F4-DE7F52BB16D4.dita"><apiname>CCamera::CustomInterface()</apiname></xref> function of the active <codeph>CCamera</codeph> implementation. The <codeph>CustomInterface()</codeph> function passes a UID <codeph>KECamMCameraVideoCaptureControlUid</codeph> value for the <codeph>CCamera</codeph> implementation. </info> <info>The <codeph>CCamera</codeph> implementation creates the concrete implementation of the <codeph>MCameraVideoCaptureControl</codeph> function and passes back a handle to the <codeph>CCameraVideoCaptureControl</codeph> object. </info> </step> <step id="GUID-1F00FA5C-498E-505F-8A2B-B1DB2E5528C4"><cmd/><info>Call the <xref href="GUID-021C509B-C821-3401-B2F4-DE7F52BB16D4.dita"><apiname>MCaptureVideoObserver</apiname></xref> function to notify when the video capture operations are ready. </info> </step> <step id="GUID-02A5B55C-7BF4-5740-9AA6-DE93C764F572"><cmd/><info>Call <xref href="GUID-021C509B-C821-3401-B2F4-DE7F52BB16D4.dita"><apiname>CCameraVideoCaptureControl::GetVideoCaptureSupportInfoL()</apiname></xref> to identify which video capture modes are supported by the <codeph>CCamera</codeph> implementation. </info> </step> <step id="GUID-4618EA07-9B5A-509C-8196-4C545A2CA014"><cmd/><info>Call the <xref href="GUID-021C509B-C821-3401-B2F4-DE7F52BB16D4.dita"><apiname>TPrepareVideoParameters::SetVideoCaptureType()</apiname></xref> function to set the desired video capture mode as the <codeph>EClientVideoCapture</codeph> or <codeph>EDirectVideoCapture</codeph> mode. </info> </step> <step id="GUID-F2EE097C-A418-51EB-9870-3E0C665B5D9D"><cmd/><info>Set the value of <xref href="GUID-021C509B-C821-3401-B2F4-DE7F52BB16D4.dita"><apiname>CCameraVideoCaptureControl::TPrepareVideoParameter::iFormat()</apiname></xref> to the <codeph>EFormatEncodedH264</codeph> value for the <codeph>CCamera</codeph> implementation. This <codeph>CCamera</codeph> implementation supports the H264 video encoding data format. </info> </step> <step id="GUID-84015E19-B259-59DD-B178-7B04EBAC7514"><cmd/><info>Prepare video capture by using the <xref href="GUID-021C509B-C821-3401-B2F4-DE7F52BB16D4.dita"><apiname>CCameraVideoCaptureControl::PrepareVideoCapture()</apiname></xref> asynchronous function. The <codeph>PrepareVideoCapture()</codeph> function performs setup and allocation of memory before calling the <codeph>StartVideoCapture()</codeph> function, in order to keep minimum latency of the <codeph>PrepareVideoCapture()</codeph> function. </info> </step> <step id="GUID-BEE6A815-D252-5958-A7CA-CD481FB30A9C"><cmd/><info>Notify the Ecam client to complete the video capture preparation using the <xref href="GUID-021C509B-C821-3401-B2F4-DE7F52BB16D4.dita"><apiname>KUidECamEventVideoCaptureControlPrepareComplete</apiname></xref> event. </info> </step> <step id="GUID-629707E2-1139-5A1D-A366-4442440A77F2"><cmd/><info>Call the <xref href="GUID-021C509B-C821-3401-B2F4-DE7F52BB16D4.dita"><apiname>CCameraVideoCaptureControl::StartVideoCaptureL()</apiname></xref> function to start video capture. </info> </step> <step id="GUID-0AC88670-8F5A-53D6-88C8-4D3C741D7114"><cmd/><info>Call the <xref href="GUID-021C509B-C821-3401-B2F4-DE7F52BB16D4.dita"><apiname>CCamera::CCameraVideoCaptureControl::PauseVideoCapture()</apiname></xref> function to pause the on-going video capture. </info> </step> <step id="GUID-072B351C-23E9-5BCD-8E25-371B24B6708F"><cmd/><info>Call the <xref href="GUID-021C509B-C821-3401-B2F4-DE7F52BB16D4.dita"><apiname>CcameraVideoCaptureControl::GetPrepareVideoParameterl()</apiname></xref> function to retrieve the current prepare video parameters. The current video capture mode is retrieved by the <xref href="GUID-021C509B-C821-3401-B2F4-DE7F52BB16D4.dita"><apiname>TPrepareVideoParameters::VideoCaptureMode()</apiname></xref> function. </info> </step> <step id="GUID-DFED1955-7B01-549E-8966-69E972DAACD2"><cmd/><info>Call the <xref href="GUID-021C509B-C821-3401-B2F4-DE7F52BB16D4.dita"><apiname>CCamera::CCameraVideoCaptureControl::ResumeVideoCaptureL()</apiname></xref> function to resume the on-going video capture. </info> </step> <step id="GUID-4A7B8939-36FF-5484-9450-7914DA5E52E7"><cmd/><info>Call the <xref href="GUID-021C509B-C821-3401-B2F4-DE7F52BB16D4.dita"><apiname>CCamera::CCameraVideoCaptureControl::StopVideoCapture()</apiname></xref> function to stop video capture. </info> </step> <step id="GUID-799FED22-0DBA-5625-BF8E-20B2FEF87D99"><cmd/><info>Call the <xref href="GUID-021C509B-C821-3401-B2F4-DE7F52BB16D4.dita"><apiname>CCameraVideoCaptureControl::ReleaseVideoResource()</apiname></xref> function to release the video resource, which is allocated while performing the <codeph>PrepareVideoCapture()</codeph> function. </info> </step> <step id="GUID-941398B5-722A-57CA-95FF-220E3C6DECE6"><cmd/><info>If an error occurs while performing video capture, call the <xref href="GUID-021C509B-C821-3401-B2F4-DE7F52BB16D4.dita"><apiname>MCaptureVideoObserver::DirectVideoCaptureFailed()</apiname></xref> function. Any video capture operation is stopped. </info> </step> </steps> <example><title>Example</title> <p>The following example code snippet illustrates video capture using H264 encoding: </p> <codeblock id="GUID-20E7DB2D-56B3-5E64-8B8F-C91188BB93D7" xml:space="preserve">
 
    12 <task id="GUID-D038D77F-A6B8-5A18-8978-4981AE8D0F35" xml:lang="en"><title> Using
 
       
    13 the Encoded H264 Video Frames to Capture Video</title><shortdesc>This topic describes how to use the encoded H264 video frames in
 
       
    14 the Ecam video capture function to capture the video data. </shortdesc><prolog><metadata><keywords/></metadata></prolog><taskbody>
 
       
    15 <prereq id="GUID-E8812B46-29C5-56D8-9658-B0B03D601B2C"><p>You need to be familiar
 
       
    16 with the <xref href="GUID-AB9A3EA2-2B99-4502-A161-8EE5BF477D41.dita">Capturing
 
       
    17 a Video Clip</xref> tutorial. </p> </prereq>
 
       
    18 <context id="GUID-3B0CFDEE-297B-56D0-A73A-B45C2E8C550C"><p>The H264 video
 
       
    19 encoder provides a new, high quality video data encoding format for Ecam.
 
       
    20 Ecam allows the device to capture video frames which are encoded in the H264
 
       
    21 format. The Ecam video capture function supports the H264 video capture format
 
       
    22 by default. You can select the H264 video capture format when preparing video
 
       
    23 capture. </p> </context>
 
       
    24 <steps id="GUID-459D27D6-C0F7-5B94-8E34-C250AF3B6B77">
 
       
    25 <step id="GUID-4A02BBE6-CDAE-5FD1-8F05-30867627197B"><cmd/>
 
       
    26 <stepxmp>Call the <xref href="GUID-D74635DE-C5D8-3A9A-ABDD-8324D8EFF460.dita#GUID-D74635DE-C5D8-3A9A-ABDD-8324D8EFF460/GUID-657990CF-32FF-34A0-9D82-FAC1E7913494"><apiname>CCamera::CCameraVideoCaptureControl::NewL(CCamera
 
       
    27 &amp;,MCaptureVideoObserver &amp;)</apiname></xref> function to create an object
 
       
    28 that maps the exported call to an internal object of the <xref href="GUID-11495CEA-9F67-3B9A-A35C-E7555ED28316.dita"><apiname>MCameraVideoCaptureControl</apiname></xref> function. </stepxmp>
 
       
    29 </step>
 
       
    30 <step id="GUID-480FA9CE-DC0A-5586-A4C2-A2DEB1D7BCEE"><cmd/>
 
       
    31 <info>Pass a handle to the <xref href="GUID-11495CEA-9F67-3B9A-A35C-E7555ED28316.dita"><apiname>MCameraVideoCaptureControl</apiname></xref> function.
 
       
    32 This implementation creates a handle to the <xref href="GUID-021C509B-C821-3401-B2F4-DE7F52BB16D4.dita#GUID-021C509B-C821-3401-B2F4-DE7F52BB16D4/GUID-D74635DE-C5D8-3A9A-ABDD-8324D8EFF460"><apiname>CCamera::CCameraVideoCaptureControl</apiname></xref> object
 
       
    33 by the active <xref href="GUID-021C509B-C821-3401-B2F4-DE7F52BB16D4.dita"><apiname>CCamera</apiname></xref> during the construction phase. </info>
 
       
    34 <info>The <codeph>CCameraVideoCaptureControl</codeph> object makes an internal
 
       
    35 call to the <xref href="GUID-021C509B-C821-3401-B2F4-DE7F52BB16D4.dita#GUID-021C509B-C821-3401-B2F4-DE7F52BB16D4/GUID-2F2F5EB8-1009-306D-A7C4-25BE5A39AA39"><apiname>CCamera::CustomInterface(TUid)</apiname></xref> function of
 
       
    36 the active <codeph>CCamera</codeph> implementation. The <codeph>CustomInterface()</codeph> function
 
       
    37 passes a UID <codeph>KECamMCameraVideoCaptureControlUid</codeph> value for
 
       
    38 the <codeph>CCamera</codeph> implementation. </info>
 
       
    39 <info>The <codeph>CCamera</codeph> implementation creates the concrete implementation
 
       
    40 of the <codeph>MCameraVideoCaptureControl</codeph> function and passes back
 
       
    41 a handle to the <codeph>CCameraVideoCaptureControl</codeph> object. </info>
 
       
    42 </step>
 
       
    43 <step id="GUID-1F00FA5C-498E-505F-8A2B-B1DB2E5528C4"><cmd/>
 
       
    44 <info>Call the <xref href="GUID-7FAEB878-52B1-3A54-9607-69AE09AB8AEB.dita"><apiname>MCaptureVideoObserver</apiname></xref> function to notify
 
       
    45 when the video capture operations are ready. </info>
 
       
    46 </step>
 
       
    47 <step id="GUID-02A5B55C-7BF4-5740-9AA6-DE93C764F572"><cmd/>
 
       
    48 <info>Call <xref href="GUID-D74635DE-C5D8-3A9A-ABDD-8324D8EFF460.dita#GUID-D74635DE-C5D8-3A9A-ABDD-8324D8EFF460/GUID-4876C362-8BA1-3E91-9A3A-203FCC6F70DB"><apiname>CCamera::CCameraVideoCaptureControl::GetVideoCaptureSupportInfoL(TInt
 
       
    49 &amp;)const</apiname></xref> to identify which video capture modes are supported
 
       
    50 by the <codeph>CCamera</codeph> implementation. </info>
 
       
    51 </step>
 
       
    52 <step id="GUID-4618EA07-9B5A-509C-8196-4C545A2CA014"><cmd/>
 
       
    53 <info>Call the <xref href="GUID-1D8E709A-35E2-3CBE-A222-F8BA17A294DA.dita#GUID-1D8E709A-35E2-3CBE-A222-F8BA17A294DA/GUID-9069A4C8-CBEE-351B-8512-F5858F6387CD"><apiname>CCamera::CCameraVideoCaptureControl::TPrepareVideoParameters::SetVideoCaptureType(CCamera::CCameraVideoCaptureControl::TVideoCaptureType)</apiname></xref> function to set the desired video capture mode as the <codeph>EClientVideoCapture</codeph> or <codeph>EDirectVideoCapture</codeph> mode. </info>
 
       
    54 </step>
 
       
    55 <step id="GUID-F2EE097C-A418-51EB-9870-3E0C665B5D9D"><cmd/>
 
       
    56 <info>Set the value of <xref href="GUID-007358AE-9795-33EB-A3BE-4788D309135D.dita#GUID-007358AE-9795-33EB-A3BE-4788D309135D/GUID-B533837C-5670-3115-9DAC-3C45B0A274E4"><apiname>CCamera::CCameraVideoCaptureControl::TPrepareVideoParameters::iFormat</apiname></xref> to
 
       
    57 the <codeph>EFormatEncodedH264</codeph> value for the <codeph>CCamera</codeph> implementation.
 
       
    58 This <codeph>CCamera</codeph> implementation supports the H264 video encoding
 
       
    59 data format. </info>
 
       
    60 </step>
 
       
    61 <step id="GUID-84015E19-B259-59DD-B178-7B04EBAC7514"><cmd/>
 
       
    62 <info>Prepare video capture by using the <xref href="GUID-D74635DE-C5D8-3A9A-ABDD-8324D8EFF460.dita#GUID-D74635DE-C5D8-3A9A-ABDD-8324D8EFF460/GUID-91EA4417-6AF2-391E-BBB2-A6E202F835BB"><apiname>CCamera::CCameraVideoCaptureControl::PrepareVideoCapture(const
 
       
    63 TPrepareVideoParameters &amp;)</apiname></xref> asynchronous function. The <codeph>PrepareVideoCapture()</codeph> function
 
       
    64 performs setup and allocation of memory before calling the <codeph>StartVideoCapture()</codeph> function,
 
       
    65 in order to keep minimum latency of the <codeph>PrepareVideoCapture()</codeph> function. </info>
 
       
    66 </step>
 
       
    67 <step id="GUID-BEE6A815-D252-5958-A7CA-CD481FB30A9C"><cmd/>
 
       
    68 <info>Notify the Ecam client to complete the video capture preparation using
 
       
    69 the <xref href="GUID-203BEBE6-F7B8-30EA-824B-AA45B88304E1.dita"><apiname>KUidECamEventVideoCaptureControlPrepareComplete</apiname></xref> event. </info>
 
       
    70 </step>
 
       
    71 <step id="GUID-629707E2-1139-5A1D-A366-4442440A77F2"><cmd/>
 
       
    72 <info>Call the <xref href="GUID-D74635DE-C5D8-3A9A-ABDD-8324D8EFF460.dita#GUID-D74635DE-C5D8-3A9A-ABDD-8324D8EFF460/GUID-774897D4-271E-3D7D-AAA6-033D34A39D74"><apiname>CCamera::CCameraVideoCaptureControl::StartVideoCaptureL()</apiname></xref> function
 
       
    73 to start video capture. </info>
 
       
    74 </step>
 
       
    75 <step id="GUID-0AC88670-8F5A-53D6-88C8-4D3C741D7114"><cmd/>
 
       
    76 <info>Call the <xref href="GUID-D74635DE-C5D8-3A9A-ABDD-8324D8EFF460.dita#GUID-D74635DE-C5D8-3A9A-ABDD-8324D8EFF460/GUID-5EB82FE6-4025-3F78-9DAD-6851086A46C6"><apiname>CCamera::CCameraVideoCaptureControl::PauseVideoCapture()</apiname></xref> function
 
       
    77 to pause the on-going video capture. </info>
 
       
    78 </step>
 
       
    79 <step id="GUID-072B351C-23E9-5BCD-8E25-371B24B6708F"><cmd/>
 
       
    80 <info>Call the <xref href="GUID-D74635DE-C5D8-3A9A-ABDD-8324D8EFF460.dita#GUID-D74635DE-C5D8-3A9A-ABDD-8324D8EFF460/GUID-AAECC4A5-742A-3B17-9FBE-8051EF891476"><apiname>CCamera::CCameraVideoCaptureControl::GetPrepareVideoParametersL(TPrepareVideoParameters
 
       
    81 &amp;)const</apiname></xref> function to retrieve the current prepare video parameters.
 
       
    82 The current video capture type is retrieved by the <xref href="GUID-007358AE-9795-33EB-A3BE-4788D309135D.dita#GUID-007358AE-9795-33EB-A3BE-4788D309135D/GUID-ED307366-65E3-3557-9479-463A595D34BC"><apiname>CCamera::CCameraVideoCaptureControl::TPrepareVideoParameters::VideoCaptureType()const</apiname></xref> function. </info>
 
       
    83 </step>
 
       
    84 <step id="GUID-DFED1955-7B01-549E-8966-69E972DAACD2"><cmd/>
 
       
    85 <info>Call the <xref href="GUID-D74635DE-C5D8-3A9A-ABDD-8324D8EFF460.dita#GUID-D74635DE-C5D8-3A9A-ABDD-8324D8EFF460/GUID-D9BECEAD-8695-3B8B-A537-9F7B96EF1A2A"><apiname>CCamera::CCameraVideoCaptureControl::ResumeVideoCaptureL()</apiname></xref> function
 
       
    86 to resume the on-going video capture. </info>
 
       
    87 </step>
 
       
    88 <step id="GUID-4A7B8939-36FF-5484-9450-7914DA5E52E7"><cmd/>
 
       
    89 <info>Call the <xref href="GUID-D74635DE-C5D8-3A9A-ABDD-8324D8EFF460.dita#GUID-D74635DE-C5D8-3A9A-ABDD-8324D8EFF460/GUID-017E7D68-9971-3966-B863-95471AC8636F"><apiname>CCamera::CCameraVideoCaptureControl::StopVideoCapture()</apiname></xref> function
 
       
    90 to stop video capture. </info>
 
       
    91 </step>
 
       
    92 <step id="GUID-799FED22-0DBA-5625-BF8E-20B2FEF87D99"><cmd/>
 
       
    93 <info>Call the <xref href="GUID-D74635DE-C5D8-3A9A-ABDD-8324D8EFF460.dita#GUID-D74635DE-C5D8-3A9A-ABDD-8324D8EFF460/GUID-3234F65D-A8FC-334E-B1A5-4382862B071C"><apiname>CCamera::CCameraVideoCaptureControl::ReleaseVideoResource()()</apiname></xref> function
 
       
    94 to release the video resource, which is allocated while performing the <codeph>PrepareVideoCapture()</codeph> function. </info>
 
       
    95 </step>
 
       
    96 <step id="GUID-941398B5-722A-57CA-95FF-220E3C6DECE6"><cmd/>
 
       
    97 <info>If an error occurs while performing video capture, call the <xref href="GUID-7FAEB878-52B1-3A54-9607-69AE09AB8AEB.dita#GUID-7FAEB878-52B1-3A54-9607-69AE09AB8AEB/GUID-5B505097-BA38-3CF9-86D8-EA62EC2CFBB4"><apiname>MCaptureVideoObserver::DirectVideoCaptureFailed(TInt)</apiname></xref> function. Any video capture operation is stopped. </info>
 
       
    98 </step>
 
       
    99 </steps>
 
       
   100 <example><title>Example</title> <p>The following example code snippet illustrates
 
       
   101 video capture using H264 encoding: </p> <codeblock id="GUID-20E7DB2D-56B3-5E64-8B8F-C91188BB93D7" xml:space="preserve">
 
    13 
   102 
    14 CCamera* camera = NULL;
 
   103 CCamera* camera = NULL;
 
    15 MCameraObserver2* observer2 = NULL;
 
   104 MCameraObserver2* observer2 = NULL;
 
    16 
   105 
    17 CCamera::CCameraVideoCaptureControl* videocapture = NULL;
 
   106 CCamera::CCameraVideoCaptureControl* videocapture = NULL;
 
    48 
   137 
    49 CCamera::CCameraVideoCaptureControl::TVideoCaptureType retrievedVideoCaptureType;
 
   138 CCamera::CCameraVideoCaptureControl::TVideoCaptureType retrievedVideoCaptureType;
 
    50 retrievedVideoCaptureType = retrievedVideoParam.VideoCaptureType();
 
   139 retrievedVideoCaptureType = retrievedVideoParam.VideoCaptureType();
 
    51 
   140 
    52 
   141 
    53 </codeblock> </example> </taskbody><related-links><link href="GUID-9DE1CE5D-F148-5A7E-908A-DDD57A32C629.dita"><linktext>Camera API</linktext> </link> <link href="GUID-9014ED9B-B0A0-5C95-9C5B-7D2F658C757F.dita"><linktext>Accessing and Power Control of
 
   142 </codeblock> </example>
 
    54                 Camera</linktext> </link> <link href="GUID-FAB548CF-24EB-52D1-A7A1-9446BA67C7A5.dita"><linktext>Camera Preset Support</linktext> </link> <link href="GUID-DA26D246-D74A-529F-9F81-11B45669103F.dita"><linktext>Capturing Image</linktext> </link> </related-links></task>
 
   143 </taskbody><related-links>
 
       
   144 <link href="GUID-FAB548CF-24EB-52D1-A7A1-9446BA67C7A5.dita"><linktext>Camera Preset
 
       
   145 Support</linktext></link>
 
       
   146 <link href="GUID-A1D2C673-3B91-403A-800B-5E1504FB19EE.dita"><linktext>Capturing
 
       
   147 Still Images</linktext></link>
 
       
   148 </related-links></task>
MCL/sftools/depl/docscontent