[libcamera-devel] [PATCH v2 6/6] src: ipa: raspberrypi: Move initial frame drop decision to AGC/AWB

[Laurent Pinchart]

Hi David,

Thank you for the patch.

On Mon, Dec 07, 2020 at 06:01:21PM +0000, David Plowman wrote:
> Previously the CamHelper was returning the number of frames to drop
> (on account of AGC/AWB converging). This wasn't really appropriate,
> it's better for the algorithms to do it as they know how many frames
> they might need.
> 
> The CamHelper::HideFramesStartup method should now just be returning
> the number of frames to hide because they're bad/invalid in some way,
> not worrying about the AGC/AWB. For many sensors, the correct value
> for this is zero. But the ov5647 needs updating as it must return 2.
> 
> Signed-off-by: David Plowman <david.plowman at raspberrypi.com>
> ---
>  src/ipa/raspberrypi/cam_helper.cpp        |  6 +++---
>  src/ipa/raspberrypi/cam_helper_ov5647.cpp | 10 ++++++++++
>  src/ipa/raspberrypi/raspberrypi.cpp       | 16 ++++++++++++++++
>  3 files changed, 29 insertions(+), 3 deletions(-)
> 
> diff --git a/src/ipa/raspberrypi/cam_helper.cpp b/src/ipa/raspberrypi/cam_helper.cpp
> index c8ac3232..6efa0d7f 100644
> --- a/src/ipa/raspberrypi/cam_helper.cpp
> +++ b/src/ipa/raspberrypi/cam_helper.cpp
> @@ -82,10 +82,10 @@ bool CamHelper::SensorEmbeddedDataPresent() const
>  unsigned int CamHelper::HideFramesStartup() const
>  {
>  	/*
> -	 * By default, hide 6 frames completely at start-up while AGC etc. sort
> -	 * themselves out (converge).
> +	 * The number of frames when a camera first starts that shouldn't be
> +	 * displayed as they are invalid in some way.
>  	 */
> -	return 6;
> +	return 0;
>  }
>  
>  unsigned int CamHelper::HideFramesModeSwitch() const
> diff --git a/src/ipa/raspberrypi/cam_helper_ov5647.cpp b/src/ipa/raspberrypi/cam_helper_ov5647.cpp
> index dc5d8275..0b841cd1 100644
> --- a/src/ipa/raspberrypi/cam_helper_ov5647.cpp
> +++ b/src/ipa/raspberrypi/cam_helper_ov5647.cpp
> @@ -19,6 +19,7 @@ public:
>  	uint32_t GainCode(double gain) const override;
>  	double Gain(uint32_t gain_code) const override;
>  	void GetDelays(int &exposure_delay, int &gain_delay) const override;
> +	unsigned int HideFramesStartup() const override;
>  	unsigned int HideFramesModeSwitch() const override;
>  	unsigned int MistrustFramesStartup() const override;
>  	unsigned int MistrustFramesModeSwitch() const override;
> @@ -54,6 +55,15 @@ void CamHelperOv5647::GetDelays(int &exposure_delay, int &gain_delay) const
>  	gain_delay = 2;
>  }
>  
> +unsigned int CamHelperOv5647::HideFramesStartup() const
> +{
> +	/*
> +	 * On startup, we get a couple of under-exposed frames which
> +	 * we don't want shown.
> +	 */
> +	return 2;
> +}
> +

Now both HideFramesStartup() and HideFramesModeSwitch() always return
the same value. Should they be merged into a single function ? This can
be done in a separate patch.

Reviewed-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>

>  unsigned int CamHelperOv5647::HideFramesModeSwitch() const
>  {
>  	/*
> diff --git a/src/ipa/raspberrypi/raspberrypi.cpp b/src/ipa/raspberrypi/raspberrypi.cpp
> index 0e89af00..da92e492 100644
> --- a/src/ipa/raspberrypi/raspberrypi.cpp
> +++ b/src/ipa/raspberrypi/raspberrypi.cpp
> @@ -193,6 +193,22 @@ int IPARPi::start(const IPAOperationData &ipaConfig, IPAOperationData *result)
>  	if (firstStart_) {
>  		dropFrame = helper_->HideFramesStartup();
>  		mistrustCount_ = helper_->MistrustFramesStartup();
> +
> +		/* The AGC and/or AWB algorithms may want us to drop more frames. */
> +		unsigned int convergence_frames = 0;
> +		RPiController::AgcAlgorithm *agc = dynamic_cast<RPiController::AgcAlgorithm *>(
> +			controller_.GetAlgorithm("agc"));
> +		if (agc)
> +			convergence_frames = agc->GetConvergenceFrames(mistrustCount_);
> +
> +		RPiController::AwbAlgorithm *awb = dynamic_cast<RPiController::AwbAlgorithm *>(
> +			controller_.GetAlgorithm("awb"));
> +		if (awb)
> +			convergence_frames = std::max(convergence_frames,
> +						      awb->GetConvergenceFrames(mistrustCount_));
> +
> +		dropFrame = std::max(dropFrame, convergence_frames);
> +		LOG(IPARPI, Debug) << "Drop " << dropFrame << " frames on startup";
>  	} else {
>  		dropFrame = helper_->HideFramesModeSwitch();
>  		mistrustCount_ = helper_->MistrustFramesModeSwitch();

-- 
Regards,

Laurent Pinchart