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  1. #1
    Registered User
    Join Date
    Mar 2010
    Posts
    3

    Back camera frame rate issue, Can't get it to work in 30 fps

    Hey,

    I've been trying to get the back camera in a N85 device to start video capturing in 30 fps and although there is clearly a frame rate index for 30 fps it won't open, and instead it opens up in 15 fps.

    Here is a little method that iterates through to possible frame rates available and stores the indexes of 15,30 fps for later use.
    The LoggerOutNum calls are just a simple log tool that writes to a text file.

    Code:
    	void GetFrameRateIndex(CCamera *a_pCamera, TCameraInfo &a_tCameraInfo, TInt &a_nSize, TInt* p_pCamVideoFrameRateIndexes ){
    		
    		TReal32 rFrameRate;
    		//iterate through all frame rates
    		for (TInt i=0;i<a_tCameraInfo.iNumVideoFrameRatesSupported;i++)
    	    {    	
    	    	//get frame rate for current index
    	    	a_pCamera->EnumerateVideoFrameRates(rFrameRate, i, CCamera::EFormatYUV420Planar, a_nSize);
    			if ( (TInt)rFrameRate > 13 && (TInt)rFrameRate < 17)
    				{
    				LoggerOutNum(_L("rFrameRate in 15 fps found it is "),(TInt)rFrameRate);
    				LoggerOutNum(_L("rFrameRate in 15 fps found index is "),i);
    				p_pCamVideoFrameRateIndexes[CamEnums::Fps15] = i;
    				}
    			if ( (TInt)rFrameRate > 28 && (TInt)rFrameRate < 32)
    				{
    				LoggerOutNum(_L("rFrameRate in 30 fps found it is "),(TInt)rFrameRate);
    				LoggerOutNum(_L("rFrameRate in 30 fps found index is "),i);
    				p_pCamVideoFrameRateIndexes[CamEnums::Fps30] = i;
    				}
    			
    
    	    	
    	    }
    This is what I get from the logger when a query is done on the front and back cameras.

    Back camera
    rFrameRate in 30 fps found it is 30
    rFrameRate in 30 fps found index is 0
    rFrameRate in 15 fps found it is 15
    rFrameRate in 15 fps found index is 1

    Front camera
    rFrameRate in 15 fps found it is 15
    rFrameRate in 15 fps found index is 0

    As you can see it is clear that the 30 fps option is available.

    When I use
    Code:
    	TRAP(aError,m_pCamera->PrepareVideoCaptureL(m_pCamInfo->nBackVideoOutFormat,
    				m_pCamInfo->nBackVideoFrameSizeIndex,
    				m_pCamInfo->pBackVideoFrameRateIndexes[m_nFpsInUse], 2, 1));
    Where m_pCamInfo->pBackVideoFrameRateIndexes[m_nFpsInUse] = 0 which is the index that got stored in an earlier stage.

    After setting up the camera it is opened and I get 15 fps instead of 30.

    I've double checked the entire process and the indexes being used + the fps calculation, are correct.

    does anyone has any idea of why this is happening ? is this some kind of a known issue with the camera api ?

    Thank you for your time,

    Ita
    Last edited by itaita; 2010-05-09 at 15:05.

  2. #2
    Nokia Developer Moderator
    Join Date
    Feb 2006
    Location
    Oslo, Norway
    Posts
    28,740

    Re: Back camera frame rate issue, Can't get to work in 30 fps

    To be honest I have never tried, but you may have to use TCameraInfo::iMaxFramesPerBufferSupported for getting the highest frame rate (e.g. the frequency of callbacks might be limited for performance reasons, but you could get multiple frames per FrameBufferReady).

  3. #3
    Registered User
    Join Date
    Mar 2010
    Posts
    3

    Re: Back camera frame rate issue, Can't get to work in 30 fps

    Thank you for the reply

    As for now I would rather not to go in the direction you've offered because it will cost too much in dev time.

    Let me just add that when testing the same code on a N86 device which is also FP2, I get the opposite behavior.
    I can't open the back camera on 15 fps and it keeps opening on 30 fps..
    Note that the indexes shown in this case has the same structure as on the N85 device.

    Is it possible that in the N86 case there is a low boundary on the fps selection ? I don't see the point in applying such a limitation on the camera fps...

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