diff --git a/include/libcamera/internal/software_isp/software_isp.h b/include/libcamera/internal/software_isp/software_isp.h
index 8956978c..ae64b247 100644
--- a/include/libcamera/internal/software_isp/software_isp.h
+++ b/include/libcamera/internal/software_isp/software_isp.h
@@ -89,7 +89,8 @@ private:
 	void saveIspParams(uint32_t paramsBufferId);
 	void releaseIspParams(uint32_t paramsBufferId);
 	void setSensorCtrls(const ControlList &sensorControls);
-	void statsReady(uint32_t frame, uint32_t bufferId);
+	void statsReady(uint32_t frame, const uint32_t statsBufferId);
+	void statsProcessed(const uint32_t statsBufferId);
 	void inputReady(FrameBuffer *input);
 	void outputReady(FrameBuffer *output);
 
diff --git a/include/libcamera/ipa/soft.mojom b/include/libcamera/ipa/soft.mojom
index 86dd988f..7b85c454 100644
--- a/include/libcamera/ipa/soft.mojom
+++ b/include/libcamera/ipa/soft.mojom
@@ -25,10 +25,11 @@ interface IPASoftInterface {
 
 	[async] queueRequest(uint32 frame, libcamera.ControlList sensorControls);
 	prepare(uint32 frame, uint32 paramsBufferId);
-	[async] processStats(uint32 frame, uint32 bufferId, libcamera.ControlList sensorControls);
+	[async] processStats(uint32 frame, uint32 statsBufferId, libcamera.ControlList sensorControls);
 };
 
 interface IPASoftEventInterface {
 	setSensorControls(libcamera.ControlList sensorControls);
+	statsProcessed(uint32 statsBufferId);
 	setIspParams(uint32 paramsBufferId);
 };
diff --git a/src/ipa/simple/soft_simple.cpp b/src/ipa/simple/soft_simple.cpp
index 50f8f194..3c95c4d9 100644
--- a/src/ipa/simple/soft_simple.cpp
+++ b/src/ipa/simple/soft_simple.cpp
@@ -266,7 +266,7 @@ void IPASoftSimple::prepare(const uint32_t frame,
 
 void IPASoftSimple::processStats(
 	const uint32_t frame,
-	[[maybe_unused]] const uint32_t bufferId,
+	const uint32_t statsBufferId,
 	const ControlList &sensorControls)
 {
 	IPAFrameContext &frameContext = context_.frameContexts.get(frame);
@@ -285,6 +285,7 @@ void IPASoftSimple::processStats(
 	ControlList metadata(controls::controls);
 	for (auto const &algo : algorithms())
 		algo->process(context_, frame, frameContext, stats_, metadata);
+	statsProcessed.emit(statsBufferId);
 
 	/* Sanity check */
 	if (!sensorControls.contains(V4L2_CID_EXPOSURE) ||
diff --git a/src/libcamera/pipeline/simple/simple.cpp b/src/libcamera/pipeline/simple/simple.cpp
index ebead8f0..d9791ab1 100644
--- a/src/libcamera/pipeline/simple/simple.cpp
+++ b/src/libcamera/pipeline/simple/simple.cpp
@@ -295,7 +295,7 @@ private:
 	void conversionInputDone(FrameBuffer *buffer);
 	void conversionOutputDone(FrameBuffer *buffer);
 
-	void ispStatsReady(uint32_t frame, uint32_t bufferId);
+	void ispStatsReady(uint32_t frame, const uint32_t statsBufferId);
 	void setSensorControls(const ControlList &sensorControls);
 };
 
@@ -901,10 +901,11 @@ void SimpleCameraData::conversionOutputDone(FrameBuffer *buffer)
 		pipe->completeRequest(request);
 }
 
-void SimpleCameraData::ispStatsReady(uint32_t frame, uint32_t bufferId)
+void SimpleCameraData::ispStatsReady(uint32_t frame,
+				     const uint32_t statsBufferId)
 {
 	swIsp_->processStats(
-		frame, bufferId,
+		frame, statsBufferId,
 		delayedCtrls_->get(frame));
 }
 
diff --git a/src/libcamera/software_isp/debayer.cpp b/src/libcamera/software_isp/debayer.cpp
index 52df8c23..af54bb18 100644
--- a/src/libcamera/software_isp/debayer.cpp
+++ b/src/libcamera/software_isp/debayer.cpp
@@ -94,9 +94,10 @@ Debayer::~Debayer()
  */
 
 /**
- * \fn void Debayer::process(uint32_t frame, const uint32_t paramsBufferId, FrameBuffer *input, FrameBuffer *output)
+ * \fn void Debayer::process(uint32_t frame, const uint32_t statsBufferId, const uint32_t paramsBufferId, FrameBuffer *input, FrameBuffer *output)
  * \brief Process the bayer data into the requested format
  * \param[in] frame The frame number
+ * \param[in] statsBufferId The id of the stats buffer to use
  * \param[in] paramsBufferId The id of the params buffer in use
  * \param[in] input The input buffer
  * \param[in] output The output buffer
diff --git a/src/libcamera/software_isp/debayer.h b/src/libcamera/software_isp/debayer.h
index 251b14fd..0be7c59a 100644
--- a/src/libcamera/software_isp/debayer.h
+++ b/src/libcamera/software_isp/debayer.h
@@ -41,7 +41,7 @@ public:
 	strideAndFrameSize(const PixelFormat &outputFormat, const Size &size) = 0;
 
 	virtual void process(uint32_t frame,
-			     const uint32_t paramsBufferId,
+			     const uint32_t statsBufferId, const uint32_t paramsBufferId,
 			     FrameBuffer *input, FrameBuffer *output) = 0;
 
 	virtual SizeRange sizes(PixelFormat inputFormat, const Size &inputSize) = 0;
diff --git a/src/libcamera/software_isp/debayer_cpu.cpp b/src/libcamera/software_isp/debayer_cpu.cpp
index d3831474..14bd58b5 100644
--- a/src/libcamera/software_isp/debayer_cpu.cpp
+++ b/src/libcamera/software_isp/debayer_cpu.cpp
@@ -742,7 +742,7 @@ static inline int64_t timeDiff(timespec &after, timespec &before)
 }
 
 void DebayerCpu::process(uint32_t frame,
-			 const uint32_t paramsBufferId,
+			 const uint32_t statsBufferId, const uint32_t paramsBufferId,
 			 FrameBuffer *input, FrameBuffer *output)
 {
 	timespec frameStartTime;
@@ -772,7 +772,7 @@ void DebayerCpu::process(uint32_t frame,
 		return;
 	}
 
-	stats_->startFrame();
+	stats_->startFrame(statsBufferId);
 
 	if (inputConfig_.patternSize.height == 2)
 		process2(in.planes()[0].data(), out.planes()[0].data());
@@ -799,12 +799,7 @@ void DebayerCpu::process(uint32_t frame,
 		}
 	}
 
-	/*
-	 * Buffer ids are currently not used, so pass zeros as its parameter.
-	 *
-	 * \todo Pass real bufferId once stats buffer passing is changed.
-	 */
-	stats_->finishFrame(frame, 0);
+	stats_->finishFrame(frame, statsBufferId);
 	outputBufferReady.emit(output);
 	inputBufferReady.emit(input);
 }
diff --git a/src/libcamera/software_isp/debayer_cpu.h b/src/libcamera/software_isp/debayer_cpu.h
index f25520be..7fb399b0 100644
--- a/src/libcamera/software_isp/debayer_cpu.h
+++ b/src/libcamera/software_isp/debayer_cpu.h
@@ -39,7 +39,7 @@ public:
 	std::tuple<unsigned int, unsigned int>
 	strideAndFrameSize(const PixelFormat &outputFormat, const Size &size);
 	void process(uint32_t frame,
-		     const uint32_t paramsBufferId,
+		     const uint32_t statsBufferId, const uint32_t paramsBufferId,
 		     FrameBuffer *input, FrameBuffer *output);
 	SizeRange sizes(PixelFormat inputFormat, const Size &inputSize);
 
diff --git a/src/libcamera/software_isp/software_isp.cpp b/src/libcamera/software_isp/software_isp.cpp
index db77f6f9..5d9f5008 100644
--- a/src/libcamera/software_isp/software_isp.cpp
+++ b/src/libcamera/software_isp/software_isp.cpp
@@ -120,6 +120,7 @@ SoftwareIsp::SoftwareIsp(PipelineHandler *pipe, const CameraSensor *sensor,
 		return;
 	}
 
+	ipa_->statsProcessed.connect(this, &SoftwareIsp::statsProcessed);
 	ipa_->setIspParams.connect(this, &SoftwareIsp::saveIspParams);
 	ipa_->setSensorControls.connect(this, &SoftwareIsp::setSensorCtrls);
 
@@ -386,8 +387,10 @@ void SoftwareIsp::process(uint32_t frame, FrameBuffer *input, FrameBuffer *outpu
 	const uint32_t paramsBufferId = availableParams_.front();
 	availableParams_.pop();
 	ipa_->prepare(frame, paramsBufferId);
+	const uint32_t statsBufferId = 0;
 	debayer_->invokeMethod(&DebayerCpu::process,
-			       ConnectionTypeQueued, frame, paramsBufferId, input, output);
+			       ConnectionTypeQueued, frame,
+			       statsBufferId, paramsBufferId, input, output);
 }
 
 void SoftwareIsp::saveIspParams(uint32_t paramsBufferId)
@@ -405,9 +408,13 @@ void SoftwareIsp::setSensorCtrls(const ControlList &sensorControls)
 	setSensorControls.emit(sensorControls);
 }
 
-void SoftwareIsp::statsReady(uint32_t frame, uint32_t bufferId)
+void SoftwareIsp::statsReady(uint32_t frame, const uint32_t statsBufferId)
+{
+	ispStatsReady.emit(frame, statsBufferId);
+}
+
+void SoftwareIsp::statsProcessed([[maybe_unused]] const uint32_t statsBufferId)
 {
-	ispStatsReady.emit(frame, bufferId);
 }
 
 void SoftwareIsp::inputReady(FrameBuffer *input)
diff --git a/src/libcamera/software_isp/swstats_cpu.cpp b/src/libcamera/software_isp/swstats_cpu.cpp
index a9b1f35a..b8ee06a0 100644
--- a/src/libcamera/software_isp/swstats_cpu.cpp
+++ b/src/libcamera/software_isp/swstats_cpu.cpp
@@ -298,7 +298,7 @@ void SwStatsCpu::statsGBRG10PLine0(const uint8_t *src[])
  *
  * This may only be called after a successful setWindow() call.
  */
-void SwStatsCpu::startFrame(void)
+void SwStatsCpu::startFrame([[maybe_unused]] const uint32_t statsBufferId)
 {
 	if (window_.width == 0)
 		LOG(SwStatsCpu, Error) << "Calling startFrame() without setWindow()";
@@ -314,10 +314,10 @@ void SwStatsCpu::startFrame(void)
  *
  * This may only be called after a successful setWindow() call.
  */
-void SwStatsCpu::finishFrame(uint32_t frame, uint32_t bufferId)
+void SwStatsCpu::finishFrame(uint32_t frame, const uint32_t statsBufferId)
 {
 	*sharedStats_ = stats_;
-	statsReady.emit(frame, bufferId);
+	statsReady.emit(frame, statsBufferId);
 }
 
 /**
diff --git a/src/libcamera/software_isp/swstats_cpu.h b/src/libcamera/software_isp/swstats_cpu.h
index 26a2f462..402eef2d 100644
--- a/src/libcamera/software_isp/swstats_cpu.h
+++ b/src/libcamera/software_isp/swstats_cpu.h
@@ -40,8 +40,8 @@ public:
 
 	int configure(const StreamConfiguration &inputCfg);
 	void setWindow(const Rectangle &window);
-	void startFrame();
-	void finishFrame(uint32_t frame, uint32_t bufferId);
+	void startFrame(const uint32_t statsBufferId);
+	void finishFrame(uint32_t frame, const uint32_t statsBufferId);
 
 	void processLine0(unsigned int y, const uint8_t *src[])
 	{