[libcamera-devel] [PATCH v3 2/2] android: jpeg: Support a initial set of EXIF metadata tags

Kieran Bingham kieran.bingham at ideasonboard.com
Thu Aug 27 12:20:58 CEST 2020 

Hi Umang,

In the $SUBJECT 's/a/an/'

On 27/08/2020 10:49, Umang Jain wrote:
> From: Kieran Bingham <kieran.bingham at ideasonboard.com>

I think this one at least should be your authorship.

You've done way more work on this than me ;-)

I can adapt when applying...


> Create a Exif object with various metadata tags set, just before

s/a/an/

> the encoder starts to encode the frame. The object is passed
> directly as libcamera::Span<> to make sure EXIF tags can be set
> at a single place i.e. in CameraDevice and the encoder only has

s/at/in/

> the job to write the data in the final output.
> 
> Signed-off-by: Kieran Bingham <kieran.bingham at ideasonboard.com>
> Signed-off-by: Umang Jain <email at uajain.com>

Reviewed-by: Kieran Bingham <kieran.bingham at ideasonboard.com>


> ---
>  src/android/camera_device.cpp        | 18 +++++++-
>  src/android/jpeg/encoder.h           |  3 +-
>  src/android/jpeg/encoder_libjpeg.cpp |  9 +++-
>  src/android/jpeg/encoder_libjpeg.h   |  3 +-
>  src/android/jpeg/exif.cpp            | 62 ++++++++++++++++++++++++++++
>  src/android/jpeg/exif.h              |  9 ++++
>  6 files changed, 100 insertions(+), 4 deletions(-)
> 
> diff --git a/src/android/camera_device.cpp b/src/android/camera_device.cpp
> index de6f86f..54ca9c6 100644
> --- a/src/android/camera_device.cpp
> +++ b/src/android/camera_device.cpp
> @@ -24,6 +24,7 @@
>  #include "system/graphics.h"
>  
>  #include "jpeg/encoder_libjpeg.h"
> +#include "jpeg/exif.h"
>  
>  using namespace libcamera;
>  
> @@ -1434,7 +1435,22 @@ void CameraDevice::requestComplete(Request *request)
>  			continue;
>  		}
>  
> -		int jpeg_size = encoder->encode(buffer, mapped.maps()[0]);
> +		/* Set EXIF metadata for various tags. */
> +		Exif exif;
> +		/* \todo Set Make and Model from external vendor tags. */
> +		exif.setMake("libcamera");
> +		exif.setModel("cameraModel");
> +		exif.setOrientation(orientation_);
> +		exif.setSize(cameraStream->size);
> +		/*
> +		 * We set the frame's EXIF timestamp as the time of encode.
> +		 * Since the precision we need for EXIF timestamp is only one
> +		 * second, it is good enough.
> +		 */
> +		exif.setTimestamp(std::time(nullptr));
> +		exif.generate();
> +
> +		int jpeg_size = encoder->encode(buffer, mapped.maps()[0], exif.data());

Ok, I do like the explicit exif.data() accessor seeing it in use there.


>  		if (jpeg_size < 0) {
>  			LOG(HAL, Error) << "Failed to encode stream image";
>  			status = CAMERA3_BUFFER_STATUS_ERROR;
> diff --git a/src/android/jpeg/encoder.h b/src/android/jpeg/encoder.h
> index f9eb88e..cf26d67 100644
> --- a/src/android/jpeg/encoder.h
> +++ b/src/android/jpeg/encoder.h
> @@ -18,7 +18,8 @@ public:
>  
>  	virtual int configure(const libcamera::StreamConfiguration &cfg) = 0;
>  	virtual int encode(const libcamera::FrameBuffer *source,
> -			   const libcamera::Span<uint8_t> &destination) = 0;
> +			   const libcamera::Span<uint8_t> &destination,
> +			   const libcamera::Span<const uint8_t> &exifData) = 0;
>  };
>  
>  #endif /* __ANDROID_JPEG_ENCODER_H__ */
> diff --git a/src/android/jpeg/encoder_libjpeg.cpp b/src/android/jpeg/encoder_libjpeg.cpp
> index 977538c..58bc1ca 100644
> --- a/src/android/jpeg/encoder_libjpeg.cpp
> +++ b/src/android/jpeg/encoder_libjpeg.cpp
> @@ -180,7 +180,8 @@ void EncoderLibJpeg::compressNV(const libcamera::MappedBuffer *frame)
>  }
>  
>  int EncoderLibJpeg::encode(const FrameBuffer *source,
> -			   const libcamera::Span<uint8_t> &dest)
> +			   const libcamera::Span<uint8_t> &dest,
> +			   const libcamera::Span<const uint8_t> &exifData)
>  {
>  	MappedFrameBuffer frame(source, PROT_READ);
>  	if (!frame.isValid()) {
> @@ -214,5 +215,11 @@ int EncoderLibJpeg::encode(const FrameBuffer *source,
>  
>  	jpeg_finish_compress(&compress_);
>  
> +	if (exifData.size())
> +		/* Store Exif data in the JPEG_APP1 data block. */
> +		jpeg_write_marker(&compress_, JPEG_APP0 + 1,
> +				  static_cast<const JOCTET *>(exifData.data()),
> +				  exifData.size());
> +
>  	return size;
>  }
> diff --git a/src/android/jpeg/encoder_libjpeg.h b/src/android/jpeg/encoder_libjpeg.h
> index aed081a..1e8df05 100644
> --- a/src/android/jpeg/encoder_libjpeg.h
> +++ b/src/android/jpeg/encoder_libjpeg.h
> @@ -22,7 +22,8 @@ public:
>  
>  	int configure(const libcamera::StreamConfiguration &cfg) override;
>  	int encode(const libcamera::FrameBuffer *source,
> -		   const libcamera::Span<uint8_t> &destination) override;
> +		   const libcamera::Span<uint8_t> &destination,
> +		   const libcamera::Span<const uint8_t> &exifData) override;
>  
>  private:
>  	void compressRGB(const libcamera::MappedBuffer *frame);
> diff --git a/src/android/jpeg/exif.cpp b/src/android/jpeg/exif.cpp
> index ce9c69b..56733fd 100644
> --- a/src/android/jpeg/exif.cpp
> +++ b/src/android/jpeg/exif.cpp
> @@ -157,6 +157,68 @@ int Exif::setString(ExifIfd ifd, ExifTag tag, ExifFormat format, const std::stri
>  	return 0;
>  }
>  
> +int Exif::setMake(const std::string &make)
> +{
> +	return setString(EXIF_IFD_0, EXIF_TAG_MAKE, EXIF_FORMAT_ASCII, make);
> +}
> +
> +int Exif::setModel(const std::string &model)
> +{
> +	return setString(EXIF_IFD_0, EXIF_TAG_MODEL, EXIF_FORMAT_ASCII, model);
> +}
> +
> +int Exif::setSize(Size size)
> +{
> +	setShort(EXIF_IFD_0, EXIF_TAG_IMAGE_LENGTH, size.height);
> +	setLong(EXIF_IFD_EXIF, EXIF_TAG_PIXEL_Y_DIMENSION, size.height);
> +
> +	setShort(EXIF_IFD_0, EXIF_TAG_IMAGE_WIDTH, size.width);
> +	setLong(EXIF_IFD_EXIF, EXIF_TAG_PIXEL_X_DIMENSION, size.width);
> +
> +	return 0;
> +}
> +
> +int Exif::setTimestamp(const time_t timestamp)
> +{
> +	char str[20];
> +	std::strftime(str, sizeof(str), "%Y:%m:%d %H:%M:%S",
> +		      std::localtime(&timestamp));
> +	std::string ts(str);
> +	int ret = -1;
> +
> +	ret = setString(EXIF_IFD_0, EXIF_TAG_DATE_TIME, EXIF_FORMAT_ASCII, ts);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = setString(EXIF_IFD_EXIF, EXIF_TAG_DATE_TIME_ORIGINAL, EXIF_FORMAT_ASCII, ts);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = setString(EXIF_IFD_EXIF, EXIF_TAG_DATE_TIME_DIGITIZED, EXIF_FORMAT_ASCII, ts);
> +	if (ret < 0)
> +		return ret;
> +
> +	return ret;
> +}
> +
> +int Exif::setOrientation(int orientation)
> +{
> +	int value = 1;
> +	switch (orientation) {
> +	case 90:
> +		value = 6;
> +		break;
> +	case 180:
> +		value = 3;
> +		break;
> +	case 270:
> +		value = 8;
> +		break;
> +	}
> +
> +	return setShort(EXIF_IFD_0, EXIF_TAG_ORIENTATION, value);
> +}
> +
>  int Exif::generate()
>  {
>  	if (exif_data_) {
> diff --git a/src/android/jpeg/exif.h b/src/android/jpeg/exif.h
> index 3a132ba..102b07c 100644
> --- a/src/android/jpeg/exif.h
> +++ b/src/android/jpeg/exif.h
> @@ -9,8 +9,10 @@
>  
>  #include <libexif/exif-data.h>
>  
> +#include <libcamera/geometry.h>
>  #include <libcamera/span.h>
>  
> +#include <ctime>
>  #include <string>
>  
>  class Exif
> @@ -19,6 +21,13 @@ public:
>  	Exif();
>  	~Exif();
>  
> +	int setMake(const std::string &make);
> +	int setModel(const std::string &model);
> +
> +	int setOrientation(int orientation);
> +	int setSize(libcamera::Size size);
> +	int setTimestamp(const time_t timestamp);
> +
>  	libcamera::Span<const uint8_t> data() const { return { exif_data_, size_ }; }
>  	int generate();
>  
> 

-- 
Regards
--
Kieran

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