[libcamera-devel] [PATCH v4 10/11] ipa: rkisp1: Introduce AGC
Kieran Bingham
kieran.bingham at ideasonboard.com
Wed Nov 24 15:30:23 CET 2021
Quoting Jean-Michel Hautbois (2021-11-24 13:40:18)
> Now that we have IPAContext and Algorithm, we can implement a simple AGC
> based on the IPU3 one. It is very similar, except that there is no
> histogram used for an inter quantile mean. The RkISP1 is returning a 5x5
> array (for V10) of luminance means. Estimating the relative luminance is
> thus a simple mean of all the blocks already calculated by the ISP.
>
> Signed-off-by: Jean-Michel Hautbois <jeanmichel.hautbois at ideasonboard.com>
>
> ---
> v4:
> - use #pragma once
> - Return filtered value from the function
> - Store line duration in IPASessionConfiguration
> - Use the hw revision to configure the number of AE cells
> ---
> src/ipa/rkisp1/algorithms/agc.cpp | 279 ++++++++++++++++++++++++++
> src/ipa/rkisp1/algorithms/agc.h | 45 +++++
> src/ipa/rkisp1/algorithms/meson.build | 1 +
> src/ipa/rkisp1/ipa_context.cpp | 45 +++++
> src/ipa/rkisp1/ipa_context.h | 19 ++
> src/ipa/rkisp1/rkisp1.cpp | 73 ++++---
> 6 files changed, 424 insertions(+), 38 deletions(-)
> create mode 100644 src/ipa/rkisp1/algorithms/agc.cpp
> create mode 100644 src/ipa/rkisp1/algorithms/agc.h
>
> diff --git a/src/ipa/rkisp1/algorithms/agc.cpp b/src/ipa/rkisp1/algorithms/agc.cpp
> new file mode 100644
> index 00000000..84ff8c7a
> --- /dev/null
> +++ b/src/ipa/rkisp1/algorithms/agc.cpp
> @@ -0,0 +1,279 @@
> +/* SPDX-License-Identifier: LGPL-2.1-or-later */
> +/*
> + * Copyright (C) 2021, Ideas On Board
> + *
> + * agc.cpp - AGC/AEC mean-based control algorithm
> + */
> +
> +#include "agc.h"
> +
> +#include <algorithm>
> +#include <chrono>
> +#include <cmath>
> +
> +#include <libcamera/base/log.h>
> +
> +#include <libcamera/ipa/core_ipa_interface.h>
> +
> +/**
> + * \file agc.h
> + */
> +
> +namespace libcamera {
> +
> +using namespace std::literals::chrono_literals;
> +
> +namespace ipa::rkisp1::algorithms {
> +
> +/**
> + * \class Agc
> + * \brief A mean-based auto-exposure algorithm
> + */
> +
> +LOG_DEFINE_CATEGORY(RkISP1Agc)
> +
> +/* Limits for analogue gain values */
> +static constexpr double kMinAnalogueGain = 1.0;
> +static constexpr double kMaxAnalogueGain = 8.0;
> +
> +/* \todo Honour the FrameDurationLimits control instead of hardcoding a limit */
> +static constexpr utils::Duration kMaxShutterSpeed = 60ms;
> +
> +/* Number of frames to wait before calculating stats on minimum exposure */
> +static constexpr uint32_t kNumStartupFrames = 10;
> +
> +/*
> + * Relative luminance target.
> + *
> + * It's a number that's chosen so that, when the camera points at a grey
> + * target, the resulting image brightness is considered right.
> + */
> +static constexpr double kRelativeLuminanceTarget = 0.4;
> +
> +Agc::Agc()
> + : frameCount_(0), currentExposure_(0s)
> +{
> +}
> +
> +/**
> + * \brief Configure the AGC given a configInfo
> + * \param[in] context The shared IPA context
> + * \param[in] configInfo The IPA configuration data
> + *
> + * \return 0
> + */
> +int Agc::configure(IPAContext &context,
> + [[maybe_unused]] const IPACameraSensorInfo &configInfo)
> +{
> + /* Configure the default exposure and gain. */
> + context.frameContext.agc.gain = std::max(context.configuration.agc.minAnalogueGain, kMinAnalogueGain);
> + context.frameContext.agc.exposure = 10ms / context.configuration.agc.lineDuration;
> +
> + /*
> + * According to the RkISP1 documentation:
> + * - versions <= V11 have RKISP1_CIF_ISP_AE_MEAN_MAX_V10 entries,
> + * - versions >= V12 have RKISP1_CIF_ISP_AE_MEAN_MAX_V12 entries.
> + */
> + if (context.configuration.hw.revision < RKISP1_V12)
> + numCells_ = RKISP1_CIF_ISP_AE_MEAN_MAX_V10;
> + else
> + numCells_ = RKISP1_CIF_ISP_AE_MEAN_MAX_V12;
> +
> + return 0;
> +}
> +
> +/**
> + * \brief Apply a filter on the exposure value to limit the speed of changes
> + */
> +utils::Duration Agc::filterExposure()
> +{
> + utils::Duration filteredExposure = currentExposure_;
> + double speed = 0.2;
> +
> + /* Adapt instantly if we are in startup phase */
> + if (frameCount_ < kNumStartupFrames)
> + speed = 1.0;
> +
> + if (filteredExposure == 0s) {
> + filteredExposure = currentExposure_;
Is this right?
I read this as:
{
utils::Duration filteredExposure = currentExposure_;
if (filteredExposure == 0s) {
filteredExposure = currentExposure_; // already set.
}
return filteredExposure; // Return 0s.
}
> + } else {
> + /*
> + * If we are close to the desired result, go faster to avoid making
> + * multiple micro-adjustments.
> + * \todo Make this customisable?
> + */
> + if (filteredExposure < 1.2 * currentExposure_ &&
> + filteredExposure > 0.8 * currentExposure_)
> + speed = sqrt(speed);
And this now reads as:
fE = cE;
if (fE < 1.2 * cE) && (fe > 0.8 * cE) // Always true.
speed = sqrt(speed);
> +
> + filteredExposure = speed * currentExposure_ +
> + filteredExposure * (1.0 - speed);
> + }
> +
> + LOG(RkISP1Agc, Debug) << "After filtering, total_exposure " << filteredExposure;
> +
> + return filteredExposure;
> +}
> +
> +/**
> + * \brief Estimate the new exposure and gain values
> + * \param[inout] frameContext The shared IPA frame Context
> + * \param[in] yGain The gain calculated on the current brightness level
> + */
> +void Agc::computeExposure(IPAContext &context, double yGain)
> +{
> + IPASessionConfiguration &configuration = context.configuration;
> + IPAFrameContext &frameContext = context.frameContext;
> +
> + /* Get the effective exposure and gain applied on the sensor. */
> + uint32_t exposure = frameContext.sensor.exposure;
> + double analogueGain = frameContext.sensor.gain;
> +
> + utils::Duration minShutterSpeed = configuration.agc.minShutterSpeed;
> + utils::Duration maxShutterSpeed = std::min(configuration.agc.maxShutterSpeed,
> + kMaxShutterSpeed);
> +
> + double minAnalogueGain = std::max(configuration.agc.minAnalogueGain,
> + kMinAnalogueGain);
> + double maxAnalogueGain = std::min(configuration.agc.maxAnalogueGain,
> + kMaxAnalogueGain);
> +
> + /* Consider within 1% of the target as correctly exposed */
> + if (std::abs(yGain - 1.0) < 0.01)
> + LOG(RkISP1Agc, Debug) << "We are well exposed (iqMean = "
> + << yGain << ")";
> +
> + /* extracted from Rpi::Agc::computeTargetExposure */
> +
> + /* Calculate the shutter time in seconds */
> + utils::Duration currentShutter = exposure * configuration.agc.lineDuration;
> +
> + /*
> + * Update the exposure value for the next computation using the values
> + * of exposure and gain really used by the sensor.
> + */
> + utils::Duration effectiveExposureValue = currentShutter * analogueGain;
> +
> + LOG(RkISP1Agc, Debug) << "Actual total exposure " << currentShutter * analogueGain
> + << " Shutter speed " << currentShutter
> + << " Gain " << analogueGain
> + << " Needed ev gain " << yGain;
> +
> + /*
> + * Calculate the current exposure value for the scene as the latest
> + * exposure value applied multiplied by the new estimated gain.
> + */
> + currentExposure_ = effectiveExposureValue * yGain;
> +
> + /* Clamp the exposure value to the min and max authorized */
> + utils::Duration maxTotalExposure = maxShutterSpeed * maxAnalogueGain;
> + currentExposure_ = std::min(currentExposure_, maxTotalExposure);
> + LOG(RkISP1Agc, Debug) << "Target total exposure " << currentExposure_
> + << ", maximum is " << maxTotalExposure;
> +
> + /*
> + * Divide the exposure value as new exposure and gain values
> + * \todo: estimate if we need to desaturate
> + */
> + utils::Duration exposureValue = filterExposure();
> + utils::Duration shutterTime;
> +
> + /*
> + * Push the shutter time up to the maximum first, and only then
> + * increase the gain.
> + */
> + shutterTime = std::clamp<utils::Duration>(exposureValue / minAnalogueGain,
> + minShutterSpeed, maxShutterSpeed);
> + double stepGain = std::clamp(exposureValue / shutterTime,
> + minAnalogueGain, maxAnalogueGain);
> + LOG(RkISP1Agc, Debug) << "Divided up shutter and gain are "
> + << shutterTime << " and "
> + << stepGain;
> +
> + /* Update the estimated exposure and gain. */
> + frameContext.agc.exposure = shutterTime / configuration.agc.lineDuration;
> + frameContext.agc.gain = stepGain;
> +}
> +
> +/**
> + * \brief Estimate the relative luminance of the frame with a given gain
> + * \param[in] ae The RkISP1 statistics and ISP results
> + * \param[in] gain The gain calculated on the current brightness level
> + * \return The relative luminance
> + *
> + * This function estimates the average relative luminance of the frame that
> + * would be output by the sensor if an additional \a gain was applied.
> + *
> + * The estimation is based on the AE statistics for the current frame. Y
> + * averages for all cells are first multiplied by the gain, and then saturated
> + * to approximate the sensor behaviour at high brightness values. The
> + * approximation is quite rough, as it doesn't take into account non-linearities
> + * when approaching saturation.
> + *
> + * The values are normalized to the [0.0, 1.0] range, where 1.0 corresponds to a
> + * theoretical perfect reflector of 100% reference white.
> + *
> + * More detailed information can be found in:
> + * https://en.wikipedia.org/wiki/Relative_luminance
> + */
> +double Agc::estimateLuminance(const rkisp1_cif_isp_ae_stat *ae,
> + double gain)
> +{
> + double ySum = 0.0;
> + unsigned int num = 0;
> +
> + /* Sum the averages, saturated to 255. */
> + for (unsigned int aeCell = 0; aeCell < numCells_; aeCell++) {
> + ySum += std::min(ae->exp_mean[aeCell] * gain, 255.0);
> + num++;
> + }
> +
> + /* \todo Weight with the AWB gains */
> +
> + return ySum / num / 255;
> +}
> +
> +/**
> + * \brief Process RkISP1 statistics, and run AGC operations
> + * \param[in] context The shared IPA context
> + * \param[in] stats The RKIsp1 statistics and ISP results
> + *
> + * Identify the current image brightness, and use that to estimate the optimal
> + * new exposure and gain for the scene.
> + */
> +void Agc::process(IPAContext &context, const rkisp1_stat_buffer *stats)
> +{
> + const rkisp1_cif_isp_stat *params = &stats->params;
> + ASSERT(stats->meas_type & RKISP1_CIF_ISP_STAT_AUTOEXP);
> +
> + const rkisp1_cif_isp_ae_stat *ae = ¶ms->ae;
> +
> + /*
> + * Estimate the gain needed to achieve a relative luminance target. To
> + * account for non-linearity caused by saturation, the value needs to be
> + * estimated in an iterative process, as multiplying by a gain will not
> + * increase the relative luminance by the same factor if some image
> + * regions are saturated.
> + */
> + double yGain = 1.0;
> + double yTarget = kRelativeLuminanceTarget;
> +
> + for (unsigned int i = 0; i < 8; i++) {
> + double yValue = estimateLuminance(ae, yGain);
> + double extra_gain = std::min(10.0, yTarget / (yValue + .001));
> +
> + yGain *= extra_gain;
> + LOG(RkISP1Agc, Debug) << "Y value: " << yValue
> + << ", Y target: " << yTarget
> + << ", gives gain " << yGain;
> + if (extra_gain < 1.01)
> + break;
> + }
> +
> + computeExposure(context, yGain);
> + frameCount_++;
> +}
> +
> +} /* namespace ipa::rkisp1::algorithms */
> +
> +} /* namespace libcamera */
> diff --git a/src/ipa/rkisp1/algorithms/agc.h b/src/ipa/rkisp1/algorithms/agc.h
> new file mode 100644
> index 00000000..a59ae9c8
> --- /dev/null
> +++ b/src/ipa/rkisp1/algorithms/agc.h
> @@ -0,0 +1,45 @@
> +/* SPDX-License-Identifier: LGPL-2.1-or-later */
> +/*
> + * Copyright (C) 2021, Ideas On Board
> + *
> + * agc.h - RkISP1 AGC/AEC mean-based control algorithm
> + */
> +#pragma once
> +
> +#include <linux/rkisp1-config.h>
> +
> +#include <libcamera/base/utils.h>
> +
> +#include <libcamera/geometry.h>
> +
> +#include "algorithm.h"
> +
> +namespace libcamera {
> +
> +struct IPACameraSensorInfo;
> +
> +namespace ipa::rkisp1::algorithms {
> +
> +class Agc : public Algorithm
> +{
> +public:
> + Agc();
> + ~Agc() = default;
> +
> + int configure(IPAContext &context, const IPACameraSensorInfo &configInfo) override;
> + void process(IPAContext &context, const rkisp1_stat_buffer *stats) override;
> +
> +private:
> + void computeExposure(IPAContext &Context, double yGain);
> + utils::Duration filterExposure();
> + double estimateLuminance(const rkisp1_cif_isp_ae_stat *ae, double gain);
> +
> + uint64_t frameCount_;
> +
> + uint32_t numCells_;
> +
> + utils::Duration currentExposure_;
> +};
> +
> +} /* namespace ipa::rkisp1::algorithms */
> +} /* namespace libcamera */
> diff --git a/src/ipa/rkisp1/algorithms/meson.build b/src/ipa/rkisp1/algorithms/meson.build
> index 1c6c59cf..a19c1a4f 100644
> --- a/src/ipa/rkisp1/algorithms/meson.build
> +++ b/src/ipa/rkisp1/algorithms/meson.build
> @@ -1,4 +1,5 @@
> # SPDX-License-Identifier: CC0-1.0
>
> rkisp1_ipa_algorithms = files([
> + 'agc.cpp',
> ])
> diff --git a/src/ipa/rkisp1/ipa_context.cpp b/src/ipa/rkisp1/ipa_context.cpp
> index 6b53dfdf..dff00362 100644
> --- a/src/ipa/rkisp1/ipa_context.cpp
> +++ b/src/ipa/rkisp1/ipa_context.cpp
> @@ -56,6 +56,24 @@ namespace libcamera::ipa::rkisp1 {
> */
>
> /**
> + * \var IPASessionConfiguration::agc
> + * \brief AGC parameters configuration of the IPA
> + *
> + * \var IPASessionConfiguration::agc.minShutterSpeed
> + * \brief Minimum shutter speed supported with the configured sensor
> + *
> + * \var IPASessionConfiguration::agc.maxShutterSpeed
> + * \brief Maximum shutter speed supported with the configured sensor
> + *
> + * \var IPASessionConfiguration::agc.minAnalogueGain
> + * \brief Minimum analogue gain supported with the configured sensor
> + *
> + * \var IPASessionConfiguration::agc.maxAnalogueGain
> + * \brief Maximum analogue gain supported with the configured sensor
> + *
> + * \var IPASessionConfiguration::agc.lineDuration
> + * \brief Line duration in microseconds
> + *
> * \var IPASessionConfiguration::hw
> * \brief RkISP1-specific hardware information
> *
> @@ -63,4 +81,31 @@ namespace libcamera::ipa::rkisp1 {
> * \brief Hardware revision of the ISP
> */
>
> +/**
> + * \var IPAFrameContext::agc
> + * \brief Context for the Automatic Gain Control algorithm
> + *
> + * The exposure and gain determined are expected to be applied to the sensor
> + * at the earliest opportunity.
> + *
> + * \var IPAFrameContext::agc.exposure
> + * \brief Exposure time expressed as a number of lines
> + *
> + * \var IPAFrameContext::agc.gain
> + * \brief Analogue gain multiplier
> + *
> + * The gain should be adapted to the sensor specific gain code before applying.
> + */
> +
> +/**
> + * \var IPAFrameContext::sensor
> + * \brief Effective sensor values
> + *
> + * \var IPAFrameContext::sensor.exposure
> + * \brief Exposure time expressed as a number of lines
> + *
> + * \var IPAFrameContext::sensor.gain
> + * \brief Analogue gain multiplier
> + */
> +
> } /* namespace libcamera::ipa::rkisp1 */
> diff --git a/src/ipa/rkisp1/ipa_context.h b/src/ipa/rkisp1/ipa_context.h
> index f9ac6833..653d7e65 100644
> --- a/src/ipa/rkisp1/ipa_context.h
> +++ b/src/ipa/rkisp1/ipa_context.h
> @@ -9,17 +9,36 @@
>
> #include <linux/rkisp1-config.h>
>
> +#include <libcamera/base/utils.h>
> +
> namespace libcamera {
>
> namespace ipa::rkisp1 {
>
> struct IPASessionConfiguration {
> + struct {
> + utils::Duration minShutterSpeed;
> + utils::Duration maxShutterSpeed;
> + double minAnalogueGain;
> + double maxAnalogueGain;
> + utils::Duration lineDuration;
> + } agc;
> +
> struct {
> rkisp1_cif_isp_version revision;
> } hw;
> };
>
> struct IPAFrameContext {
> + struct {
> + uint32_t exposure;
> + double gain;
> + } agc;
> +
> + struct {
> + uint32_t exposure;
> + double gain;
> + } sensor;
> };
>
> struct IPAContext {
> diff --git a/src/ipa/rkisp1/rkisp1.cpp b/src/ipa/rkisp1/rkisp1.cpp
> index 59676a70..5c0a0330 100644
> --- a/src/ipa/rkisp1/rkisp1.cpp
> +++ b/src/ipa/rkisp1/rkisp1.cpp
> @@ -25,6 +25,7 @@
>
> #include <libcamera/internal/mapped_framebuffer.h>
>
> +#include "algorithms/agc.h"
> #include "algorithms/algorithm.h"
> #include "libipa/camera_sensor_helper.h"
>
> @@ -34,6 +35,8 @@ namespace libcamera {
>
> LOG_DEFINE_CATEGORY(IPARkISP1)
>
> +using namespace std::literals::chrono_literals;
> +
> namespace ipa::rkisp1 {
>
> class IPARkISP1 : public IPARkISP1Interface
> @@ -75,7 +78,6 @@ private:
>
> /* revision-specific data */
> rkisp1_cif_isp_version hwRevision_;
> - unsigned int hwAeMeanMax_;
> unsigned int hwHistBinNMax_;
> unsigned int hwGammaOutMaxSamples_;
> unsigned int hwHistogramWeightGridsSize_;
> @@ -95,13 +97,11 @@ int IPARkISP1::init(const IPASettings &settings, unsigned int hwRevision)
> /* \todo Add support for other revisions */
> switch (hwRevision) {
> case RKISP1_V10:
> - hwAeMeanMax_ = RKISP1_CIF_ISP_AE_MEAN_MAX_V10;
> hwHistBinNMax_ = RKISP1_CIF_ISP_HIST_BIN_N_MAX_V10;
> hwGammaOutMaxSamples_ = RKISP1_CIF_ISP_GAMMA_OUT_MAX_SAMPLES_V10;
> hwHistogramWeightGridsSize_ = RKISP1_CIF_ISP_HISTOGRAM_WEIGHT_GRIDS_SIZE_V10;
> break;
> case RKISP1_V12:
> - hwAeMeanMax_ = RKISP1_CIF_ISP_AE_MEAN_MAX_V12;
> hwHistBinNMax_ = RKISP1_CIF_ISP_HIST_BIN_N_MAX_V12;
> hwGammaOutMaxSamples_ = RKISP1_CIF_ISP_GAMMA_OUT_MAX_SAMPLES_V12;
> hwHistogramWeightGridsSize_ = RKISP1_CIF_ISP_HISTOGRAM_WEIGHT_GRIDS_SIZE_V12;
> @@ -126,6 +126,9 @@ int IPARkISP1::init(const IPASettings &settings, unsigned int hwRevision)
> return -ENODEV;
> }
>
> + /* Construct our Algorithms */
> + algorithms_.push_back(std::make_unique<algorithms::Agc>());
> +
> return 0;
> }
>
> @@ -183,6 +186,26 @@ int IPARkISP1::configure([[maybe_unused]] const IPACameraSensorInfo &info,
> /* Set the hardware revision for the algorithms. */
> context_.configuration.hw.revision = hwRevision_;
>
> + context_.configuration.agc.lineDuration = info.lineLength * 1.0s / info.pixelRate;
> +
> + /*
> + * When the AGC computes the new exposure values for a frame, it needs
> + * to know the limits for shutter speed and analogue gain.
> + * As it depends on the sensor, update it with the controls.
> + *
> + * \todo take VBLANK into account for maximum shutter speed
> + */
> + context_.configuration.agc.minShutterSpeed = minExposure_ * context_.configuration.agc.lineDuration;
> + context_.configuration.agc.maxShutterSpeed = maxExposure_ * context_.configuration.agc.lineDuration;
> + context_.configuration.agc.minAnalogueGain = camHelper_->gain(minGain_);
> + context_.configuration.agc.maxAnalogueGain = camHelper_->gain(maxGain_);
> +
> + for (auto const &algo : algorithms_) {
> + int ret = algo->configure(context_, info);
> + if (ret)
> + return ret;
> + }
> +
> return 0;
> }
>
> @@ -227,6 +250,9 @@ void IPARkISP1::processEvent(const RkISP1Event &event)
> reinterpret_cast<rkisp1_stat_buffer *>(
> mappedBuffers_.at(bufferId).planes()[0].data());
>
> + context_.frameContext.sensor.exposure = event.sensorControls.get(V4L2_CID_EXPOSURE).get<int32_t>();
> + context_.frameContext.sensor.gain = camHelper_->gain(event.sensorControls.get(V4L2_CID_ANALOGUE_GAIN).get<int32_t>());
> +
> updateStatistics(frame, stats);
> break;
> }
> @@ -271,44 +297,12 @@ void IPARkISP1::queueRequest(unsigned int frame, rkisp1_params_cfg *params,
> void IPARkISP1::updateStatistics(unsigned int frame,
> const rkisp1_stat_buffer *stats)
> {
> - const rkisp1_cif_isp_stat *params = &stats->params;
> unsigned int aeState = 0;
>
> - if (stats->meas_type & RKISP1_CIF_ISP_STAT_AUTOEXP) {
> - const rkisp1_cif_isp_ae_stat *ae = ¶ms->ae;
> -
> - const unsigned int target = 60;
> -
> - unsigned int value = 0;
> - unsigned int num = 0;
> - for (unsigned int i = 0; i < hwAeMeanMax_; i++) {
> - if (ae->exp_mean[i] <= 15)
> - continue;
> -
> - value += ae->exp_mean[i];
> - num++;
> - }
> - value /= num;
> + for (auto const &algo : algorithms_)
> + algo->process(context_, stats);
>
> - double factor = (double)target / value;
> -
> - if (frame % 3 == 0) {
> - double exposure;
> -
> - exposure = factor * exposure_ * gain_ / minGain_;
> - exposure_ = std::clamp<uint64_t>((uint64_t)exposure,
> - minExposure_,
> - maxExposure_);
> -
> - exposure = exposure / exposure_ * minGain_;
> - gain_ = std::clamp<uint64_t>((uint64_t)exposure,
> - minGain_, maxGain_);
> -
> - setControls(frame + 1);
> - }
> -
> - aeState = fabs(factor - 1.0f) < 0.05f ? 2 : 1;
> - }
> + setControls(frame);
>
> metadataReady(frame, aeState);
> }
> @@ -318,6 +312,9 @@ void IPARkISP1::setControls(unsigned int frame)
> RkISP1Action op;
> op.op = ActionV4L2Set;
>
> + exposure_ = context_.frameContext.agc.exposure;
> + gain_ = camHelper_->gainCode(context_.frameContext.agc.gain);
> +
> ControlList ctrls(ctrls_);
> ctrls.set(V4L2_CID_EXPOSURE, static_cast<int32_t>(exposure_));
> ctrls.set(V4L2_CID_ANALOGUE_GAIN, static_cast<int32_t>(gain_));
> --
> 2.32.0
>
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