[libcamera-devel] [PATCH v2] android: jpeg: Split and pass the thumbnail planes to encoder

[Umang Jain]

After multi-planar support was introduced for jpeg encoding as well,
EncoderLibJpeg::encode() expects a vector of planes as the source of
framebuffer to be encoded. Currently, we are passing a contiguous buffer
which is treated as only one plane (instead of two, as thumbnail is NV12).

Hence, split the thumbnail data into respective planes according to NV12.
This fixes a crash in encoding of thumbnails.

Fixes: 894ca69f6043("android: jpeg: Support multi-planar buffers")
Signed-off-by: Umang Jain <umang.jain at ideasonboard.com>
---
Changes in v2: 
- Fix basic split logic error.
- Add Jacopo's suggestion as a \todo since it's a superior method to fix
  this.
---
 src/android/jpeg/post_processor_jpeg.cpp | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/src/android/jpeg/post_processor_jpeg.cpp b/src/android/jpeg/post_processor_jpeg.cpp
index 68d74842..1bf507a4 100644
--- a/src/android/jpeg/post_processor_jpeg.cpp
+++ b/src/android/jpeg/post_processor_jpeg.cpp
@@ -66,13 +66,23 @@ void PostProcessorJpeg::generateThumbnail(const FrameBuffer &source,
 	int ret = thumbnailEncoder_.configure(thCfg);
 
 	if (!rawThumbnail.empty() && !ret) {
+		thumbnail->resize(rawThumbnail.size());
+
 		/*
-		 * \todo Avoid value-initialization of all elements of the
-		 * vector.
+		 * Split planes manually as the encoder expects a vector of
+		 * planes.
+		 *
+		 * \todo Pass a vector of planes directly to
+		 * Thumbnailer::createThumbnailer above and remove the manual
+		 * planes split from here.
 		 */
-		thumbnail->resize(rawThumbnail.size());
+		std::vector<Span<uint8_t>> thumbnailPlanes;
+		unsigned int thumbnailSize = targetSize.height * targetSize.width;
+		thumbnailPlanes.push_back({ rawThumbnail.data(), thumbnailSize });
+		thumbnailPlanes.push_back({ rawThumbnail.data() + thumbnailSize,
+					    thumbnailSize / 2 });
 
-		int jpeg_size = thumbnailEncoder_.encode({ rawThumbnail },
+		int jpeg_size = thumbnailEncoder_.encode(thumbnailPlanes,
 							 *thumbnail, {}, quality);
 		thumbnail->resize(jpeg_size);
 
-- 
2.31.0