[libcamera-devel] [PATCH 1/2] android: camera_capabilities: Add function to convert PixelFormat to android format

[Laurent Pinchart]

Hi Hiro,

Thank you for the patch.

On Tue, Nov 30, 2021 at 09:44:27PM +0900, Hirokazu Honda wrote:
> This adds a function to CameraCapabilities of converting PixelFormat
> to android format.
> 
> Signed-off-by: Hirokazu Honda <hiroh at chromium.org>
> ---
>  src/android/camera_capabilities.cpp | 18 ++++++++++++++++++
>  src/android/camera_capabilities.h   |  2 ++
>  2 files changed, 20 insertions(+)
> 
> diff --git a/src/android/camera_capabilities.cpp b/src/android/camera_capabilities.cpp
> index f357902e..4c1dc87c 100644
> --- a/src/android/camera_capabilities.cpp
> +++ b/src/android/camera_capabilities.cpp
> @@ -545,6 +545,7 @@ int CameraCapabilities::initializeStreamConfigurations()
>  		 */
>  		if (androidFormat == HAL_PIXEL_FORMAT_BLOB) {
>  			formatsMap_[androidFormat] = formats::MJPEG;
> +			revFormatsMap_[formats::MJPEG] = androidFormat;
>  			LOG(HAL, Debug) << "Mapped Android format "
>  					<< camera3Format.name << " to "
>  					<< formats::MJPEG.toString()
> @@ -596,6 +597,7 @@ int CameraCapabilities::initializeStreamConfigurations()
>  		 * stream configurations map, by testing the image resolutions.
>  		 */
>  		formatsMap_[androidFormat] = mappedFormat;
> +		revFormatsMap_[mappedFormat] = androidFormat;
>  		LOG(HAL, Debug) << "Mapped Android format "
>  				<< camera3Format.name << " to "
>  				<< mappedFormat.toString();
> @@ -1422,6 +1424,22 @@ PixelFormat CameraCapabilities::toPixelFormat(int format) const
>  	return it->second;
>  }
>  
> +/*
> + * Translate libcamera pixel format to Android format code. -1 if no mapped
> + * android format is found.
> + */
> +int CameraCapabilities::toAndroidFormat(PixelFormat format) const
> +{
> +	auto it = revFormatsMap_.find(format);
> +	if (it == revFormatsMap_.end()) {
> +		LOG(HAL, Error) << "Requested format " << format.toString()
> +				<< " not supported";
> +		return -1;
> +	}
> +
> +	return it->second;

I think there's a conceptual problem here. While a given Android format
can always be translated to a PixelFormat, the mapping isn't 1:1. We
already map different Android formats to NV21 for instance, and I expect
this to continue as we support more formats. A reverse map is thus
ill-defined, there's no guarantee that

	toAndroidFormat(toPixelFormat(format)) == format

which I think can lead to subtle bugs. Can't we instead, in the next
patch, get the Android format from camera3Stream_->format ?

> +}
> +
>  std::unique_ptr<CameraMetadata> CameraCapabilities::requestTemplateManual() const
>  {
>  	if (!capabilities_.count(ANDROID_REQUEST_AVAILABLE_CAPABILITIES_MANUAL_SENSOR)) {
> diff --git a/src/android/camera_capabilities.h b/src/android/camera_capabilities.h
> index 2cf97ae8..df6361f1 100644
> --- a/src/android/camera_capabilities.h
> +++ b/src/android/camera_capabilities.h
> @@ -30,6 +30,7 @@ public:
>  
>  	CameraMetadata *staticMetadata() const { return staticMetadata_.get(); }
>  	libcamera::PixelFormat toPixelFormat(int format) const;
> +	int toAndroidFormat(libcamera::PixelFormat format) const;
>  	unsigned int maxJpegBufferSize() const { return maxJpegBufferSize_; }
>  
>  	std::unique_ptr<CameraMetadata> requestTemplateManual() const;
> @@ -77,6 +78,7 @@ private:
>  
>  	std::vector<Camera3StreamConfiguration> streamConfigurations_;
>  	std::map<int, libcamera::PixelFormat> formatsMap_;
> +	std::map<libcamera::PixelFormat, int> revFormatsMap_;
>  	std::unique_ptr<CameraMetadata> staticMetadata_;
>  	unsigned int maxJpegBufferSize_;
>  

-- 
Regards,

Laurent Pinchart