[v1] libcamera: software_isp: Allow limiting output sizes
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Message ID 20261011103445.156465-1-robert.mader@collabora.com
State New
Headers show
Series
  • [v1] libcamera: software_isp: Allow limiting output sizes
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Commit Message

Robert Mader Oct. 11, 2026, 10:34 a.m. UTC 
There are various scenarios where it can be useful to control the ousput
sizes of the SW-ISP inside libcamera without rebuilding the project.
Examples include:
 - Debugging and testing when one can't fully control the client
 - Forcing well working sizes on devices where the GPU/CPU are not strong
   enough for typically client-picked sizes. This can be especially
   useful on mobile devices

I plan to use this as convenience feature in Nura (formerly postmarketOS),
making it easy to ship device specific configuration files without needing
libcamera-specific downstream changes to the kernel. To me the feature
seems useful enough to upstream it, though.

>cat ~/.config/libcamera/configuration.yaml
>---
>version: 1
>configuration:
>  software_isp:
>    min_output_width: 800
>    min_output_height: 600
>    max_output_width: 1280
>    max_output_height: 720

Signed-off-by: Robert Mader <robert.mader@collabora.com>
---
 .../internal/software_isp/software_isp.h      |  1 +
 src/libcamera/software_isp/software_isp.cpp   | 20 +++++++++++++++++--
 2 files changed, 19 insertions(+), 2 deletions(-)

Patch
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diff --git a/include/libcamera/internal/software_isp/software_isp.h b/include/libcamera/internal/software_isp/software_isp.h
index b8b24bb1b113..9a14b20723e4 100644
--- a/include/libcamera/internal/software_isp/software_isp.h
+++ b/include/libcamera/internal/software_isp/software_isp.h
@@ -101,6 +101,7 @@  private:
 	DebayerParams debayerParams_;
 	DmaBufAllocator dmaHeap_;
 	bool ccmEnabled_;
+	SizeRange outputSizeLimits_;
 
 	std::unique_ptr<ipa::softisp::IPAProxySoftIsp> ipa_;
 	std::deque<FrameBuffer *> queuedInputBuffers_;
diff --git a/src/libcamera/software_isp/software_isp.cpp b/src/libcamera/software_isp/software_isp.cpp
index a40976055d63..334ba4ef90b1 100644
--- a/src/libcamera/software_isp/software_isp.cpp
+++ b/src/libcamera/software_isp/software_isp.cpp
@@ -105,8 +105,21 @@  SoftwareIsp::SoftwareIsp(PipelineHandler *pipe, const CameraSensor *sensor,
 	}
 	stats->statsReady.connect(this, &SoftwareIsp::statsReady);
 
-#if HAVE_DEBAYER_EGL
 	const GlobalConfiguration &configuration = cm._d()->configuration();
+
+	unsigned int minOutputWidth =
+		configuration.option<unsigned int>({ "software_isp", "min_output_width" }).value_or(0);
+	unsigned int minOutputHeight =
+		configuration.option<unsigned int>({ "software_isp", "min_output_height" }).value_or(0);
+	outputSizeLimits_.min = Size(minOutputWidth, minOutputHeight);
+
+	unsigned int maxOutputWidth =
+		configuration.option<unsigned int>({ "software_isp", "max_output_width" }).value_or(std::numeric_limits<unsigned int>::max());
+	unsigned int maxOutputHeight =
+		configuration.option<unsigned int>({ "software_isp", "max_output_height" }).value_or(std::numeric_limits<unsigned int>::max());
+	outputSizeLimits_.max = Size(maxOutputWidth, maxOutputHeight);
+
+#if HAVE_DEBAYER_EGL
 	std::optional<std::string> softISPMode = configuration.option<std::string>({ "software_isp", "mode" });
 	if (softISPMode) {
 		if (softISPMode != "gpu" && softISPMode != "cpu") {
@@ -243,7 +256,10 @@  SizeRange SoftwareIsp::sizes(PixelFormat inputFormat, const Size &inputSize)
 {
 	ASSERT(debayer_);
 
-	return debayer_->sizes(inputFormat, inputSize);
+	SizeRange sizes = debayer_->sizes(inputFormat, inputSize);
+	sizes.min = sizes.min.expandTo(outputSizeLimits_.min).alignUpTo(sizes.hStep, sizes.vStep);
+	sizes.max = sizes.max.boundTo(outputSizeLimits_.max).alignDownTo(sizes.hStep, sizes.vStep);
+	return sizes;
 }
 
 /**