[libcamera-devel] [PATCH 2/4] ipa: raspberrypi: Limit the calculated vblank based on the sensor mode

David Plowman david.plowman at raspberrypi.com
Thu Jan 21 15:52:53 CET 2021


Hi Naush

I don't think I can claim to understand every last nuance of this, but
let me try anyway but here goes...!

On Thu, 21 Jan 2021 at 11:58, Naushir Patuck <naush at raspberrypi.com> wrote:
>
> The existing framerate/vblank calculations did not account for the
> sensor mode limits. This commit extracts vblank limits from the sensor
> v4l2 controls, and stores it in the camera modes structure.
>
> Exposure and vblank value calculations now use values clamped to the
> sensor mode limits. The libcamera::controls::FrameDurations metadata
> return values now reflect the minimum and maximum after clamping.
>
> Signed-off-by: Naushir Patuck <naush at raspberrypi.com>
> ---
>  src/ipa/raspberrypi/cam_helper.cpp           | 16 +++---
>  src/ipa/raspberrypi/cam_helper.hpp           |  5 +-
>  src/ipa/raspberrypi/cam_helper_imx219.cpp    |  6 +--
>  src/ipa/raspberrypi/cam_helper_imx477.cpp    |  4 +-
>  src/ipa/raspberrypi/cam_helper_ov5647.cpp    |  4 +-
>  src/ipa/raspberrypi/controller/camera_mode.h |  2 +
>  src/ipa/raspberrypi/raspberrypi.cpp          | 51 ++++++++++++++------
>  7 files changed, 49 insertions(+), 39 deletions(-)
>
> diff --git a/src/ipa/raspberrypi/cam_helper.cpp b/src/ipa/raspberrypi/cam_helper.cpp
> index b7b8faf09c69..3e17255737b2 100644
> --- a/src/ipa/raspberrypi/cam_helper.cpp
> +++ b/src/ipa/raspberrypi/cam_helper.cpp
> @@ -34,9 +34,8 @@ CamHelper *CamHelper::Create(std::string const &cam_name)
>         return nullptr;
>  }
>
> -CamHelper::CamHelper(MdParser *parser, unsigned int maxFrameLength,
> -                    unsigned int frameIntegrationDiff)
> -       : parser_(parser), initialized_(false), maxFrameLength_(maxFrameLength),
> +CamHelper::CamHelper(MdParser *parser, unsigned int frameIntegrationDiff)
> +       : parser_(parser), initialized_(false),
>           frameIntegrationDiff_(frameIntegrationDiff)
>  {
>  }
> @@ -67,13 +66,12 @@ uint32_t CamHelper::GetVBlanking(double &exposure, double minFrameDuration,
>         assert(initialized_);
>
>         /*
> -        * Clamp frame length by the frame duration range and the maximum allowable
> -        * value in the sensor, given by maxFrameLength_.
> +        * minFrameDuration and maxFrameDuration will have been clamped to the
> +        * maximum allowable values in the sensor for this mode.
>          */
> -       frameLengthMin = std::clamp<uint32_t>(1e3 * minFrameDuration / mode_.line_length,
> -                                             mode_.height, maxFrameLength_);
> -       frameLengthMax = std::clamp<uint32_t>(1e3 * maxFrameDuration / mode_.line_length,
> -                                             mode_.height, maxFrameLength_);
> +       frameLengthMin = 1e3 * minFrameDuration / mode_.line_length;
> +       frameLengthMax = 1e3 * maxFrameDuration / mode_.line_length;
> +
>         /*
>          * Limit the exposure to the maximum frame duration requested, and
>          * re-calculate if it has been clipped.
> diff --git a/src/ipa/raspberrypi/cam_helper.hpp b/src/ipa/raspberrypi/cam_helper.hpp
> index b1739a57e342..14d70112cb62 100644
> --- a/src/ipa/raspberrypi/cam_helper.hpp
> +++ b/src/ipa/raspberrypi/cam_helper.hpp
> @@ -62,8 +62,7 @@ class CamHelper
>  {
>  public:
>         static CamHelper *Create(std::string const &cam_name);
> -       CamHelper(MdParser *parser, unsigned int maxFrameLength,
> -                 unsigned int frameIntegrationDiff);
> +       CamHelper(MdParser *parser, unsigned int frameIntegrationDiff);
>         virtual ~CamHelper();
>         void SetCameraMode(const CameraMode &mode);
>         MdParser &Parser() const { return *parser_; }
> @@ -86,8 +85,6 @@ protected:
>
>  private:
>         bool initialized_;
> -       /* Largest possible frame length, in units of lines. */
> -       unsigned int maxFrameLength_;
>         /*
>          * Smallest difference between the frame length and integration time,
>          * in units of lines.
> diff --git a/src/ipa/raspberrypi/cam_helper_imx219.cpp b/src/ipa/raspberrypi/cam_helper_imx219.cpp
> index 8688ec091c44..95b8e698fe3b 100644
> --- a/src/ipa/raspberrypi/cam_helper_imx219.cpp
> +++ b/src/ipa/raspberrypi/cam_helper_imx219.cpp
> @@ -56,15 +56,13 @@ private:
>          * in units of lines.
>          */
>         static constexpr int frameIntegrationDiff = 4;
> -       /* Largest possible frame length, in units of lines. */
> -       static constexpr int maxFrameLength = 0xffff;
>  };
>
>  CamHelperImx219::CamHelperImx219()
>  #if ENABLE_EMBEDDED_DATA
> -       : CamHelper(new MdParserImx219(), maxFrameLength, frameIntegrationDiff)
> +       : CamHelper(new MdParserImx219(), frameIntegrationDiff)
>  #else
> -       : CamHelper(new MdParserRPi(), maxFrameLength, frameIntegrationDiff)
> +       : CamHelper(new MdParserRPi(), frameIntegrationDiff)
>  #endif
>  {
>  }
> diff --git a/src/ipa/raspberrypi/cam_helper_imx477.cpp b/src/ipa/raspberrypi/cam_helper_imx477.cpp
> index 5396131003f1..eaa7be16d20e 100644
> --- a/src/ipa/raspberrypi/cam_helper_imx477.cpp
> +++ b/src/ipa/raspberrypi/cam_helper_imx477.cpp
> @@ -45,12 +45,10 @@ private:
>          * in units of lines.
>          */
>         static constexpr int frameIntegrationDiff = 22;
> -       /* Largest possible frame length, in units of lines. */
> -       static constexpr int maxFrameLength = 0xffdc;
>  };
>
>  CamHelperImx477::CamHelperImx477()
> -       : CamHelper(new MdParserImx477(), maxFrameLength, frameIntegrationDiff)
> +       : CamHelper(new MdParserImx477(), frameIntegrationDiff)
>  {
>  }
>
> diff --git a/src/ipa/raspberrypi/cam_helper_ov5647.cpp b/src/ipa/raspberrypi/cam_helper_ov5647.cpp
> index 2bd8a754f133..a7f417324048 100644
> --- a/src/ipa/raspberrypi/cam_helper_ov5647.cpp
> +++ b/src/ipa/raspberrypi/cam_helper_ov5647.cpp
> @@ -30,8 +30,6 @@ private:
>          * in units of lines.
>          */
>         static constexpr int frameIntegrationDiff = 4;
> -       /* Largest possible frame length, in units of lines. */
> -       static constexpr int maxFrameLength = 0xffff;
>  };
>
>  /*
> @@ -40,7 +38,7 @@ private:
>   */
>
>  CamHelperOv5647::CamHelperOv5647()
> -       : CamHelper(new MdParserRPi(), maxFrameLength, frameIntegrationDiff)
> +       : CamHelper(new MdParserRPi(), frameIntegrationDiff)
>  {
>  }
>
> diff --git a/src/ipa/raspberrypi/controller/camera_mode.h b/src/ipa/raspberrypi/controller/camera_mode.h
> index 920f11beb0b0..3baeadaca076 100644
> --- a/src/ipa/raspberrypi/controller/camera_mode.h
> +++ b/src/ipa/raspberrypi/controller/camera_mode.h
> @@ -37,6 +37,8 @@ struct CameraMode {
>         double line_length;
>         // any camera transform *not* reflected already in the camera tuning
>         libcamera::Transform transform;
> +       // minimum and maximum vblanking limits for this mode
> +       uint32_t vblank_min, vblank_max;
>  };
>
>  #ifdef __cplusplus
> diff --git a/src/ipa/raspberrypi/raspberrypi.cpp b/src/ipa/raspberrypi/raspberrypi.cpp
> index 5ccc7a6551f5..9e6e030c4997 100644
> --- a/src/ipa/raspberrypi/raspberrypi.cpp
> +++ b/src/ipa/raspberrypi/raspberrypi.cpp
> @@ -102,6 +102,7 @@ private:
>         void reportMetadata();
>         bool parseEmbeddedData(unsigned int bufferId, struct DeviceStatus &deviceStatus);
>         void processStats(unsigned int bufferId);
> +       void applyFrameDurations(double min, double max);
>         void applyAGC(const struct AgcStatus *agcStatus, ControlList &ctrls);
>         void applyAWB(const struct AwbStatus *awbStatus, ControlList &ctrls);
>         void applyDG(const struct AgcStatus *dgStatus, ControlList &ctrls);
> @@ -279,6 +280,14 @@ void IPARPi::setMode(const CameraSensorInfo &sensorInfo)
>          * the line length in pixels and the pixel rate.
>          */
>         mode_.line_length = 1e9 * sensorInfo.lineLength / sensorInfo.pixelRate;
> +
> +       /*
> +        * Set the vertical blanking (frame duration) limits for the mode to
> +        * ensure exposure and framerate calculations are clipped appropriately.
> +        */
> +       const auto itVblank = sensorCtrls_.find(V4L2_CID_VBLANK);

Are we happy to assume this exists? (I realise that if it doesn't then
everything is doomed and we probably don't care very much...)

> +       mode_.vblank_min = itVblank->second.min().get<int32_t>();
> +       mode_.vblank_max = itVblank->second.max().get<int32_t>();
>  }
>
>  void IPARPi::configure(const CameraSensorInfo &sensorInfo,
> @@ -384,8 +393,8 @@ void IPARPi::configure(const CameraSensorInfo &sensorInfo,
>                 controller_.Initialise();
>                 controllerInit_ = true;
>
> -               minFrameDuration_ = defaultMinFrameDuration;
> -               maxFrameDuration_ = defaultMaxFrameDuration;
> +               /* Supply initial values for frame durations. */
> +               applyFrameDurations(defaultMinFrameDuration, defaultMaxFrameDuration);
>
>                 /* Supply initial values for gain and exposure. */
>                 ControlList ctrls(sensorCtrls_);
> @@ -819,20 +828,7 @@ void IPARPi::queueRequest(const ControlList &controls)
>
>                 case controls::FRAME_DURATIONS: {
>                         auto frameDurations = ctrl.second.get<Span<const int64_t>>();
> -
> -                       /* This will be applied once AGC recalculations occur. */
> -                       minFrameDuration_ = frameDurations[0] ? frameDurations[0] : defaultMinFrameDuration;
> -                       maxFrameDuration_ = frameDurations[1] ? frameDurations[1] : defaultMaxFrameDuration;
> -                       maxFrameDuration_ = std::max(maxFrameDuration_, minFrameDuration_);
> -
> -                       /*
> -                        * \todo The values returned in the metadata below must be
> -                        * correctly clipped by what the sensor mode supports and
> -                        * what the AGC exposure mode or manual shutter speed limits
> -                        */
> -                       libcameraMetadata_.set(controls::FrameDurations,
> -                                              { static_cast<int64_t>(minFrameDuration_),
> -                                                static_cast<int64_t>(maxFrameDuration_) });
> +                       applyFrameDurations(frameDurations[0], frameDurations[1]);
>                         break;
>                 }
>
> @@ -991,6 +987,29 @@ void IPARPi::applyAWB(const struct AwbStatus *awbStatus, ControlList &ctrls)
>                   static_cast<int32_t>(awbStatus->gain_b * 1000));
>  }
>
> +void IPARPi::applyFrameDurations(double min, double max)

I didn't terribly like variables named just "min" and "max", as I
immediately wonder what they are the min and max of... or maybe it's
just a hangover from C programming where there often seemed to be min
and max macros flying around!

But these terribly minor things aside:

Reviewed-by: David Plowman <david.plowman at raspberrypi.com>

Thanks!
David

> +{
> +       const double minSensorFrameDuration = 1e-3 * (mode_.vblank_min + mode_.height) *
> +                                             mode_.line_length;
> +       const double maxSensorFrameDuration = 1e-3 * (mode_.vblank_max + mode_.height) *
> +                                             mode_.line_length;
> +       /*
> +        * This will only be applied once AGC recalculations occur.
> +        * The values may be clamped based on the sensor mode capabilities as well.
> +        */
> +       minFrameDuration_ = min ? min : defaultMaxFrameDuration;
> +       maxFrameDuration_ = max ? max : defaultMinFrameDuration;
> +       minFrameDuration_ = std::clamp(minFrameDuration_,
> +                                      minSensorFrameDuration, maxSensorFrameDuration);
> +       maxFrameDuration_ = std::clamp(maxFrameDuration_,
> +                                      minSensorFrameDuration, maxSensorFrameDuration);
> +
> +       /* Return the validated limits out though metadata. */
> +       libcameraMetadata_.set(controls::FrameDurations,
> +                              { static_cast<int64_t>(minFrameDuration_),
> +                                static_cast<int64_t>(maxFrameDuration_) });
> +}
> +
>  void IPARPi::applyAGC(const struct AgcStatus *agcStatus, ControlList &ctrls)
>  {
>         int32_t gainCode = helper_->GainCode(agcStatus->analogue_gain);
> --
> 2.25.1
>
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