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<concept xml:lang="en" id="GUID-469377FB-AAE8-5245-A8E1-469C65AFE5C5"><title>Stepping Frames</title><prolog><metadata><keywords/></metadata></prolog><conbody><p>This tutorial describes how to watch frames in a video clip. </p> <section><title>Purpose</title> <p>The purpose of this tutorial is to show you how to step forward and backward through video frames. </p> <p><b>Required Background</b> </p> <p>The <xref href="GUID-2DC80BA9-7AA2-5CD3-9105-1DE28CE196C1.dita">Video Client Overview</xref> introduces the video client utilities. </p> <p><b>Introduction</b> </p> <p>Frame step allows you to step the current video playback position forward or backward by a number of frames. This feature is provided by the <xref href="GUID-0F1F8AC6-B99F-3274-A785-9977197AF762.dita#GUID-0F1F8AC6-B99F-3274-A785-9977197AF762/GUID-6AA8FCCE-63B1-3EF9-8A41-7A3F1DE28E76"><apiname>CVideoPlayerUtility::StepFrameL()</apiname></xref> method and is only available when playback is paused. </p> <p> <b>Note:</b> This functionality is dependent on the capabilities of the underlying play-controller implementation and the characteristics of the video clip. </p> </section> <section><title>Using Frame Step </title> <p>The following tasks are covered in this tutorial: </p> <ul><li id="GUID-BE65641A-E30E-5C22-8C20-4642A385992E"><p><xref href="GUID-469377FB-AAE8-5245-A8E1-469C65AFE5C5.dita#GUID-469377FB-AAE8-5245-A8E1-469C65AFE5C5/GUID-F212F1A1-0ABA-599D-AC32-89D396BB6AD0">Step Frames Forward and Backward </xref>  </p> </li> </ul> <p id="GUID-F212F1A1-0ABA-599D-AC32-89D396BB6AD0"><b>Basic Procedure</b> </p> <p>The high level steps to step frames forward and backward are shown here: </p> <ol id="GUID-910FA4E1-4DE2-5D17-BDC3-F6FD2CBE0707"><li id="GUID-D1A02942-66BB-5EB5-A6F6-29B75CC81C06"><p>Create a new video player utility object. </p> </li> <li id="GUID-0ED6D9F6-A985-5968-82F8-F7E551531201"><p>Open a video clip to play. </p> </li> <li id="GUID-6D417E89-E0EE-575B-A36D-B1A838283558"><p>Use <xref href="GUID-0F1F8AC6-B99F-3274-A785-9977197AF762.dita#GUID-0F1F8AC6-B99F-3274-A785-9977197AF762/GUID-45F4B0E5-2EF4-3391-A925-DD31C9E997F6"><apiname>CVideoPlayerUtility::GetPlayRateCapabilitiesL()</apiname></xref> to check frame step is supported. This returns <xref href="GUID-F89DA3F0-2A48-3F9B-8F08-29350E92D0E4.dita"><apiname>KErrNotSupported</apiname></xref> if frame step is not supported. </p> </li> <li id="GUID-42F37141-25D8-5D62-80BE-0D5D4DD61834"><p>Call the <xref href="GUID-0F1F8AC6-B99F-3274-A785-9977197AF762.dita#GUID-0F1F8AC6-B99F-3274-A785-9977197AF762/GUID-B4FB00AA-A85B-3A3F-91BE-C5347462BA95"><apiname>CVideoPlayerUtility::Prepare()</apiname></xref> method. </p> </li> <li id="GUID-1A6B9052-812F-528E-8D76-16049EBD0591"><p>Call <xref href="GUID-0F1F8AC6-B99F-3274-A785-9977197AF762.dita#GUID-0F1F8AC6-B99F-3274-A785-9977197AF762/GUID-A9DCC4EB-B4B3-3AF4-B78C-DC3531A32DCC"><apiname>CVideoPlayerUtility::Play()</apiname></xref> to start playback. </p> </li> <li id="GUID-4D3D4426-EDB4-5F1F-A6C3-1657E1F7562E"><p>Pause playback using <xref href="GUID-0F1F8AC6-B99F-3274-A785-9977197AF762.dita#GUID-0F1F8AC6-B99F-3274-A785-9977197AF762/GUID-CCF5BF0E-BD93-34AC-812E-443ECD07FE26"><apiname>CVideoPlayerUtility::PauseL()</apiname></xref>. </p> </li> <li id="GUID-6C90DF54-997B-5D82-BD9C-94546975883A"><p>To step forward through the video frames use <xref href="GUID-0F1F8AC6-B99F-3274-A785-9977197AF762.dita#GUID-0F1F8AC6-B99F-3274-A785-9977197AF762/GUID-6AA8FCCE-63B1-3EF9-8A41-7A3F1DE28E76"><apiname>CVideoPlayerUtility::StepFrameL()</apiname></xref> and set <xref href="GUID-D39C892F-581C-3A1F-9686-4B48512C6882.dita"><apiname>aStep</apiname></xref> to a positive <xref href="GUID-7A2A43EC-6125-3BFE-834B-23C37F7B40D5.dita"><apiname>TInt</apiname></xref> value. </p> </li> <li id="GUID-F2AA5F17-0657-5C9C-B7E7-C1A6CEC8156E"><p>To step backward through the video frames use <xref href="GUID-0F1F8AC6-B99F-3274-A785-9977197AF762.dita#GUID-0F1F8AC6-B99F-3274-A785-9977197AF762/GUID-6AA8FCCE-63B1-3EF9-8A41-7A3F1DE28E76"><apiname>CVideoPlayerUtility::StepFrameL()</apiname></xref> and set <xref href="GUID-D39C892F-581C-3A1F-9686-4B48512C6882.dita"><apiname>aStep</apiname></xref> to a negative <xref href="GUID-7A2A43EC-6125-3BFE-834B-23C37F7B40D5.dita"><apiname>TInt</apiname></xref> value. </p> </li> <li id="GUID-36FD8645-3000-5E92-B316-B8462FD0B53D"><p>Call <xref href="GUID-0F1F8AC6-B99F-3274-A785-9977197AF762.dita#GUID-0F1F8AC6-B99F-3274-A785-9977197AF762/GUID-C103A911-AF93-3350-B731-C186A279F1DC"><apiname>CVideoPlayerUtility::Stop()</apiname></xref> to halt video playback. </p> </li> </ol> <p><b>Example</b> </p> <codeblock id="GUID-6EA0ADC4-A004-58BF-A9F6-2906E7663307" xml:space="preserve">// Create new video player utility object (iVideoPlayer)

// Open the video clip

// Call Prepare()

// Call Play()

iVideoPlayer->GetPlayRateCapabilitiesL(iVideoPlayRateCapabilities);

// Return the current playback rate capabilities

// Check that engine has forward capability.

if( iVideoPlayRateCapabilities.iStepForward)

{

iVideoPlayer->StepFrameL(10); // Steps to 10th frame from current.

}

else

{

// Forward is not supported.

}

// If user wants to rewind. Check that engine has rewind capability.

if( iVideoPlayRateCapabilities.iStepBackward)

{

iVideoPlayer->StepFrameL(-5); // Steps to 5th frame backward.

}

else

{

// Rewind is not supported.

}