[4/4] virtual: Align strides to 256 bytes
diff mbox series

Message ID 20261008211149.51765-5-robert.mader@collabora.com
State New
Headers show
Series
  • virtual: Support more common pixel formats
Related show

Commit Message

Robert Mader Oct. 8, 2026, 9:11 p.m. UTC 
This patch was originally developed to help debugging and testing
https://webrtc-review.googlesource.com/c/src/+/491680, however I see
some benefits in always doing it:
1. It is common for hardware ISPs to have some stride alignment - even
   though usually somewhat lower. Using the given alignment should thus
   help ensure that clients implement stride handling correctly,
   preventing cases like the one linked above where a major implemention
   went without that - unnocited - for quite a long time.
2. It makes it more likely that output buffers can be imported by GPUs
   and display engines.
2. It paves the way for GPU-accelerated frame generators (similar to
   DebayerEGL), which may become desirable going forward in order to
   provide high resolution / high framerate / high bit-depth / HDR
   content.

Signed-off-by: Robert Mader <robert.mader@collabora.com>
---
 .../pipeline/virtual/frame_generator.h        |  1 +
 .../virtual/image_frame_generator.cpp         | 23 ++++++++++---------
 .../virtual/test_pattern_generator.cpp        | 18 ++++++++++-----
 src/libcamera/pipeline/virtual/virtual.cpp    |  9 +++++---
 4 files changed, 31 insertions(+), 20 deletions(-)

Patch
diff mbox series 

diff --git a/src/libcamera/pipeline/virtual/frame_generator.h b/src/libcamera/pipeline/virtual/frame_generator.h
index 70cd92907b63..31eea6392008 100644
--- a/src/libcamera/pipeline/virtual/frame_generator.h
+++ b/src/libcamera/pipeline/virtual/frame_generator.h
@@ -23,6 +23,7 @@  public:
 	virtual int generateFrame(const StreamConfiguration *cfg,
 				  const FrameBuffer *buffer) = 0;
 
+	static constexpr unsigned int kStrideAlignment = 256;
 protected:
 	FrameGenerator() {}
 };
diff --git a/src/libcamera/pipeline/virtual/image_frame_generator.cpp b/src/libcamera/pipeline/virtual/image_frame_generator.cpp
index dcef90702e18..685c11a61029 100644
--- a/src/libcamera/pipeline/virtual/image_frame_generator.cpp
+++ b/src/libcamera/pipeline/virtual/image_frame_generator.cpp
@@ -110,11 +110,6 @@  void ImageFrameGenerator::configure(const Size &size)
 			std::make_unique<uint8_t[]>(halfSizeWidth * halfSizeHeight * 2);
 		auto &src = imageFrameDatas_[i];
 
-		/*
-		 * \todo Some platforms might enforce stride due to GPU.
-                 * The width needs to be a multiple of the stride to work
-                 * properly for now.
-		 */
 		libyuv::NV12Scale(src.Y.get(), src.size.width,
 				  src.UV.get(), src.size.width,
 				  src.size.width, src.size.height,
@@ -159,9 +154,11 @@  int ImageFrameGenerator::generateFrame(const StreamConfiguration *cfg, const Fra
 				       scaledFrameDatas_[frameIndex_].UV.get(),
 				       size.width,
 				       planes[0].data(),
-				       info.stride(size.width, 0),
+				       info.stride(size.width, 0,
+						   kStrideAlignment),
 				       planes[1].data(),
-				       info.stride(size.width, 1),
+				       info.stride(size.width, 1,
+						   kStrideAlignment),
 				       size.width, size.height);
 		break;
 	case formats::YUV420:
@@ -170,11 +167,14 @@  int ImageFrameGenerator::generateFrame(const StreamConfiguration *cfg, const Fra
 					 scaledFrameDatas_[frameIndex_].UV.get(),
 					 size.width,
 					 planes[0].data(),
-					 info.stride(size.width, 0),
+					 info.stride(size.width, 0,
+						     kStrideAlignment),
 					 planes[1].data(),
-					 info.stride(size.width, 1),
+					 info.stride(size.width, 1,
+						     kStrideAlignment),
 					 planes[2].data(),
-					 info.stride(size.width, 2),
+					 info.stride(size.width, 2,
+						     kStrideAlignment),
 					 size.width, size.height);
 		break;
 	case formats::ABGR8888:
@@ -184,7 +184,8 @@  int ImageFrameGenerator::generateFrame(const StreamConfiguration *cfg, const Fra
 					 scaledFrameDatas_[frameIndex_].UV.get(),
 					 size.width,
 					 planes[0].data(),
-					 info.stride(size.width, 0),
+					 info.stride(size.width, 0,
+						     kStrideAlignment),
 					 size.width, size.height);
 		break;
 	default:
diff --git a/src/libcamera/pipeline/virtual/test_pattern_generator.cpp b/src/libcamera/pipeline/virtual/test_pattern_generator.cpp
index d8cdc1c91c24..1892854d63d3 100644
--- a/src/libcamera/pipeline/virtual/test_pattern_generator.cpp
+++ b/src/libcamera/pipeline/virtual/test_pattern_generator.cpp
@@ -72,20 +72,25 @@  int TestPatternGenerator::generateFrame(const StreamConfiguration *cfg,
 		ret = libyuv::ARGBToNV12(template_.get(),
 					 size.width * kARGBSize,
 					 planes[0].data(),
-					 info.stride(size.width, 0),
+					 info.stride(size.width, 0,
+						     kStrideAlignment),
 					 planes[1].data(),
-					 info.stride(size.width, 1),
+					 info.stride(size.width, 1,
+						     kStrideAlignment),
 					 size.width, size.height);
 		break;
 	case formats::YUV420:
 		ret = libyuv::ARGBToI420(template_.get(),
 					 size.width * kARGBSize,
 					 planes[0].data(),
-					 info.stride(size.width, 0),
+					 info.stride(size.width, 0,
+						     kStrideAlignment),
 					 planes[1].data(),
-					 info.stride(size.width, 1),
+					 info.stride(size.width, 1,
+						     kStrideAlignment),
 					 planes[2].data(),
-					 info.stride(size.width, 2),
+					 info.stride(size.width, 2,
+						     kStrideAlignment),
 					 size.width, size.height);
 		break;
 	case formats::ABGR8888:
@@ -93,7 +98,8 @@  int TestPatternGenerator::generateFrame(const StreamConfiguration *cfg,
 		ret = libyuv::ARGBCopy(template_.get(),
 				       size.width * kARGBSize,
 				       planes[0].data(),
-				       info.stride(size.width, 0),
+				       info.stride(size.width, 0,
+						   kStrideAlignment),
 				       size.width, size.height);
 		break;
 	default:
diff --git a/src/libcamera/pipeline/virtual/virtual.cpp b/src/libcamera/pipeline/virtual/virtual.cpp
index 349cb88a3f05..ac6c5ca67aa8 100644
--- a/src/libcamera/pipeline/virtual/virtual.cpp
+++ b/src/libcamera/pipeline/virtual/virtual.cpp
@@ -231,8 +231,10 @@  CameraConfiguration::Status VirtualCameraConfiguration::validate()
 			adjusted = true;
 		}
 
-		auto stride = info.stride(cfg.size.width, 0);
-		auto frameSize = info.frameSize(cfg.size);
+		auto stride = info.stride(cfg.size.width, 0,
+					  FrameGenerator::kStrideAlignment);
+		auto frameSize = info.frameSize(cfg.size,
+						FrameGenerator::kStrideAlignment);
 		if ((cfg.stride && cfg.stride != stride) ||
 		    (cfg.frameSize && cfg.frameSize != frameSize)) {
 			status = Adjusted;
@@ -342,7 +344,8 @@  int PipelineHandlerVirtual::exportFrameBuffers([[maybe_unused]] Camera *camera,
 
 	std::vector<unsigned int> planeSizes;
 	for (size_t i = 0; i < info.numPlanes(); ++i)
-		planeSizes.push_back(info.planeSize(config.size, i));
+		planeSizes.push_back(info.planeSize(config.size, i,
+						    FrameGenerator::kStrideAlignment));
 
 	return dmaBufAllocator_.exportBuffers(config.bufferCount, planeSizes, buffers);
 }