No front camera snapshot on N96

[pavarang]

Hi,
my app requirement was to take snapshots from front camera, recognize useless (too dark or monochrome) images and save them into jpeg format.
I've succesfully accomplished it on all tested device except N96... so i'm searching a reason for it... i always have a totally black image of around 9 KB....

CCamera::ImageReady() is called with aError==KErrNone; inside this method i perform a duplication:

iBitmapSave->Reset();
TInt err = iBitmapSave->Duplicate( aBitmap->Handle() );

and err == 0

then i call my jpeg encoding method:

/*
 * Returns a buffer with encoded jpeg image
 */
HBufC8* CFrontCameraApp::GetImageBufferL(CFbsBitmap* aBitmap)
	{
		if (aBitmap == NULL)
			return HBufC8::NewL(0); 

		// set jpeg properties
		CFrameImageData* frameImageData = CFrameImageData::NewL();
		CleanupStack::PushL(frameImageData);
		TJpegImageData* imageData = new (ELeave) TJpegImageData();
		imageData->iSampleScheme  = TJpegImageData::EColor444;
		imageData->iQualityFactor = 75; //  set 90 for normal or 100 for high 
		frameImageData->AppendImageData(imageData);
				
		// convert to jpeg synchronously
		HBufC8* imageBuf = NULL;
		CImageEncoder* encoder  = CImageEncoder::DataNewL(imageBuf,_L8("image/jpeg"),CImageEncoder::EOptionAlwaysThread);
		CleanupStack::PushL(encoder);
		TRequestStatus aStatus = KErrNone; 
		encoder->Convert( &aStatus, *aBitmap, frameImageData );
		User::WaitForRequest( aStatus );
		CleanupStack::PopAndDestroy(encoder);
				
		CleanupStack::PopAndDestroy(frameImageData);
		
		return imageBuf;
	}

but i don't think the problem is in the jpeg conversion, because i used the same function to convert screenshots and it was (it is in fact) working fine in N96 too... but maybe screenshots and snapshot are taken into different memory areas?

and native camera app on N96 is taking nice snapshots in jpeg format with front camera

thank you for any hint,
regards,
pg

[wizard_hu_]

You could draw the image on the screen, just to see what it contains.
Also search for N96 in the Wiki, there are some known issues about this device, and they are actually related to the camera.

[pavarang]

You could draw the image on the screen, just to see what it contains.

yep, i'll try this one, because i'm not finding any solution...

Also search for N96 in the Wiki, there are some known issues about this device, and they are actually related to the camera.

thnx, i already did it, but i don't use any of the advanced features or settings, requirements are very simple and i didn't want to use additional wrapper if not strictly necessary....

i'll post the solution, if i ever find it....

[pavarang]

This is driving me crazy.... :-)
I've modified a HelloWorld code and added the camera part, just to focus on snapshots only.
Everything works fine on E72 and other devices i have for test, but not on N96.
I'm focusing on the basics:

iCamera = CCamera::NewL(*this,1);
...
iCamera->CameraInfo(iInfo);
iFormat = ImageFormatMax();

where

CCamera::TFormat CFrontCameraEngine::ImageFormatMax() const
{
if ( iInfo.iImageFormatsSupported & CCamera::EFormatFbsBitmapColor16M )
{
return CCamera::EFormatFbsBitmapColor16M;
}
else if ( iInfo.iImageFormatsSupported & CCamera::EFormatFbsBitmapColor64K)
{
return CCamera::EFormatFbsBitmapColor64K;
}
else
{
return CCamera::EFormatFbsBitmapColor4K;
}
}

then i retrieve the smallest supported size:

iSizeIndex = 0;
for(TInt i = (iInfo.iNumImageSizesSupported-1);i>=0;i--)
//for (TInt i=0; i< iInfo.iNumImageSizesSupported; i++)
{
TSize supportedSize;
iCamera->EnumerateCaptureSizes(supportedSize, i, iFormat);
if(supportedSize.iHeight!=0)
{
iSizeIndex = i;
break;
}
}

and the usual part:

iCamera->Reserve();
...
iCamera->PowerOn();
...
TRAPD(err,iCamera->PrepareImageCaptureL(iFormat,iSizeIndex));
...
iCamera->CaptureImage();

void CFrontCameraEngine::ImageReady(CFbsBitmap *aBitmap, HBufC8 *aData, TInt aError)
{
if(aError == KErrNone)
{
iBitmapSave->Reset();
TInt err = iBitmapSave->Duplicate( aBitmap->Handle() );
if(err != KErrNone)
{
iCamera->PowerOff();
iCamera->Release();
}

iEncoder = CImageEncoder::FileNewL(iFs, _L("C:\\provasnapshot.jpg"),_L8("image/jpeg"),CImageEncoder::EOptionAlwaysThread);
iEncoder->Convert( &iStatus, *iBitmapSave);
SetActive();
}
}

there's no error or leaving anywhere....
even into last call to RunL, that shows status equal to zero....
but the saved jpeg is totally black on N96
same totally black image using N96 rear/primary camera

i'm stucked, two FP2 devices working opposite....

i've tried to draw the snaphot as per wizard_hu suggestion, using code from Nokia example, but nothing is drawed to screen...

any suggestion is welcomed
thank you
pg

[wizard_hu_]

Just to make sure: those ...-s are asynchronous, are not they?
Also, you could make a test with the "official" Camera example (Resources above, Code examples, Symbian C++, Multimedia). The older versions are supposed to be available too, without that magical wrapper API.

[pavarang]

Just to make sure: those ...-s are asynchronous, are not they?

yes! i'm just too lazy to transcript all the xxComplete() callbacks...
and this time, just to keep everything as plain as possible, also the Convert method is left asynchronous...

Also, you could make a test with the "official" Camera example (Resources above, Code examples, Symbian C++, Multimedia). The older versions are supposed to be available too, without that magical wrapper API.

yep! my code is derived from the older example
unfortunately it doesn't compile... this evening i'll do everything to compile it, even if i'm not too optimist about the final result....
i'm wondering what's inside that magical wrapper... :-)

thnx!

[pavarang]

yep! my code is derived from the older example
unfortunately it doesn't compile... this evening i'll do everything to compile it, even if i'm not too optimist about the final result....

ok...
i've tried the provided sis of this one:
http://wiki.forum.nokia.com/index.ph...3rd_Ed_FP2.zip
but the app doesn't even start, "feature not supported", i'll try to delete autofocus part...
and then the camera wrapper (with the second version/update of the wrapper) example sis: i can take one snapshot, then everything freezes....
that's weird, 'cause people on forum isn't having all these problems with N96...

i'm wondering what's inside that magical wrapper... :-)

is this the source code?
https://projects.developer.nokia.com...rapper/browser

[pavarang]

ok, i've found at last....
on N96, and maybe on other devices, who knows?, it seems mandatory to call

iCamera->PrepareImageCaptureL(iFormat,iSizeIndex)
iCamera->StartViewFinderBitmapsL( iLandscapeSize );

instead of

iCamera->PrepareImageCaptureL(iFormat,iSizeIndex)
iCamera->CaptureImage();

then, in the callback, i wrote:

void CFrontCameraEngine::ViewFinderFrameReady(CFbsBitmap &aFrame)
{
iCamera->StopViewFinder();
iCamera->CaptureImage();
}

et voila', it ended up with the jpg file

now, the question is:
WHY??????????????????????????

why is N96 working like this and not like the other devices? or viceversa...

thnx
pg