[libcamera-devel] [RFC PATCH 1/2] android: jpeg: encoder_libjpeg Allow encoding raw frame bytes

[Umang Jain]

Allow encoding frame which are directly handed over to the encoder
via a span or vector i.e. a raw frame bytes. Introduce an overloaded
EncoderLibJpeg::encode() with libcamera::Span source parameter to
achieve this functionality. This makes the libjpeg-encoder a bit
flexible for use case such as compressing a thumbnail generated for
Exif.

Signed-off-by: Umang Jain <email at uajain.com>
---
 src/android/jpeg/encoder_libjpeg.cpp | 37 +++++++++++++++++-----------
 src/android/jpeg/encoder_libjpeg.h   |  7 ++++--
 2 files changed, 28 insertions(+), 16 deletions(-)

diff --git a/src/android/jpeg/encoder_libjpeg.cpp b/src/android/jpeg/encoder_libjpeg.cpp
index f11e004..bfaf9d5 100644
--- a/src/android/jpeg/encoder_libjpeg.cpp
+++ b/src/android/jpeg/encoder_libjpeg.cpp
@@ -104,9 +104,9 @@ int EncoderLibJpeg::configure(const StreamConfiguration &cfg)
 	return 0;
 }
 
-void EncoderLibJpeg::compressRGB(const libcamera::MappedBuffer *frame)
+void EncoderLibJpeg::compressRGB(const libcamera::Span<uint8_t> &frame)
 {
-	unsigned char *src = static_cast<unsigned char *>(frame->maps()[0].data());
+	unsigned char *src = static_cast<unsigned char *>(frame.data());
 	/* \todo Stride information should come from buffer configuration. */
 	unsigned int stride = pixelFormatInfo_->stride(compress_.image_width, 0);
 
@@ -122,7 +122,7 @@ void EncoderLibJpeg::compressRGB(const libcamera::MappedBuffer *frame)
  * Compress the incoming buffer from a supported NV format.
  * This naively unpacks the semi-planar NV12 to a YUV888 format for libjpeg.
  */
-void EncoderLibJpeg::compressNV(const libcamera::MappedBuffer *frame)
+void EncoderLibJpeg::compressNV(const libcamera::Span<uint8_t> &frame)
 {
 	uint8_t tmprowbuf[compress_.image_width * 3];
 
@@ -144,7 +144,7 @@ void EncoderLibJpeg::compressNV(const libcamera::MappedBuffer *frame)
 	unsigned int cb_pos = nvSwap_ ? 1 : 0;
 	unsigned int cr_pos = nvSwap_ ? 0 : 1;
 
-	const unsigned char *src = static_cast<unsigned char *>(frame->maps()[0].data());
+	const unsigned char *src = static_cast<unsigned char *>(frame.data());
 	const unsigned char *src_c = src + y_stride * compress_.image_height;
 
 	JSAMPROW row_pointer[1];
@@ -179,17 +179,10 @@ void EncoderLibJpeg::compressNV(const libcamera::MappedBuffer *frame)
 	}
 }
 
-int EncoderLibJpeg::encode(const FrameBuffer *source,
+int EncoderLibJpeg::encode(const libcamera::Span<uint8_t> &frame,
 			   const libcamera::Span<uint8_t> &dest,
 			   const libcamera::Span<const uint8_t> &exifData)
 {
-	MappedFrameBuffer frame(source, PROT_READ);
-	if (!frame.isValid()) {
-		LOG(JPEG, Error) << "Failed to map FrameBuffer : "
-				 << strerror(frame.error());
-		return frame.error();
-	}
-
 	unsigned char *destination = dest.data();
 	unsigned long size = dest.size();
 
@@ -215,11 +208,27 @@ int EncoderLibJpeg::encode(const FrameBuffer *source,
 			 << "x" << compress_.image_height;
 
 	if (nv_)
-		compressNV(&frame);
+		compressNV(frame);
 	else
-		compressRGB(&frame);
+		compressRGB(frame);
 
 	jpeg_finish_compress(&compress_);
 
 	return size;
 }
+
+int EncoderLibJpeg::encode(const FrameBuffer *source,
+			   const libcamera::Span<uint8_t> &dest,
+			   const libcamera::Span<const uint8_t> &exifData)
+{
+	MappedFrameBuffer frame(source, PROT_READ);
+	if (!frame.isValid()) {
+		LOG(JPEG, Error) << "Failed to map FrameBuffer : "
+				 << strerror(frame.error());
+		return frame.error();
+	}
+
+	libcamera::Span<uint8_t> src = frame.maps()[0];
+
+	return encode(src, dest, exifData);
+}
diff --git a/src/android/jpeg/encoder_libjpeg.h b/src/android/jpeg/encoder_libjpeg.h
index 934caef..bf2e512 100644
--- a/src/android/jpeg/encoder_libjpeg.h
+++ b/src/android/jpeg/encoder_libjpeg.h
@@ -21,13 +21,16 @@ public:
 	~EncoderLibJpeg();
 
 	int configure(const libcamera::StreamConfiguration &cfg) override;
+	int encode(const libcamera::Span<uint8_t> &frames,
+		   const libcamera::Span<uint8_t> &destination,
+		   const libcamera::Span<const uint8_t> &exifData);
 	int encode(const libcamera::FrameBuffer *source,
 		   const libcamera::Span<uint8_t> &destination,
 		   const libcamera::Span<const uint8_t> &exifData) override;
 
 private:
-	void compressRGB(const libcamera::MappedBuffer *frame);
-	void compressNV(const libcamera::MappedBuffer *frame);
+	void compressRGB(const libcamera::Span<uint8_t> &frame);
+	void compressNV(const libcamera::Span<uint8_t> &frame);
 
 	struct jpeg_compress_struct compress_;
 	struct jpeg_error_mgr jerr_;
-- 
2.26.2