[libcamera-devel] [RFC PATCH v2 1/2] qcam: format_converter: put parameters of different formats into union

Laurent Pinchart laurent.pinchart at ideasonboard.com
Sat Sep 12 02:44:19 CEST 2020


Hi Andrey,

Thank you for the patch.

On Tue, Sep 08, 2020 at 06:07:38PM +0300, Andrey Konovalov wrote:
> As the number of supported formats in the converter grows, having the
> format-specific parameters in a union makes the code cleaner, and save
> some amount of memory.
>
> Signed-off-by: Andrey Konovalov <andrey.konovalov at linaro.org>
> ---
>  src/qcam/format_converter.cpp | 133 ++++++++++++++++++----------------
>  src/qcam/format_converter.h   |  37 ++++++----
>  2 files changed, 92 insertions(+), 78 deletions(-)
> 
> diff --git a/src/qcam/format_converter.cpp b/src/qcam/format_converter.cpp
> index 4b9722d..3481330 100644
> --- a/src/qcam/format_converter.cpp
> +++ b/src/qcam/format_converter.cpp
> @@ -33,103 +33,103 @@ int FormatConverter::configure(const libcamera::PixelFormat &format,
>  	switch (format) {
>  	case libcamera::formats::NV12:
>  		formatFamily_ = NV;
> -		horzSubSample_ = 2;
> -		vertSubSample_ = 2;
> -		nvSwap_ = false;
> +		params_.nv.horzSubSample = 2;
> +		params_.nv.vertSubSample = 2;
> +		params_.nv.nvSwap = false;
>  		break;
>  	case libcamera::formats::NV21:
>  		formatFamily_ = NV;
> -		horzSubSample_ = 2;
> -		vertSubSample_ = 2;
> -		nvSwap_ = true;
> +		params_.nv.horzSubSample = 2;
> +		params_.nv.vertSubSample = 2;
> +		params_.nv.nvSwap = true;
>  		break;
>  	case libcamera::formats::NV16:
>  		formatFamily_ = NV;
> -		horzSubSample_ = 2;
> -		vertSubSample_ = 1;
> -		nvSwap_ = false;
> +		params_.nv.horzSubSample = 2;
> +		params_.nv.vertSubSample = 1;
> +		params_.nv.nvSwap = false;
>  		break;
>  	case libcamera::formats::NV61:
>  		formatFamily_ = NV;
> -		horzSubSample_ = 2;
> -		vertSubSample_ = 1;
> -		nvSwap_ = true;
> +		params_.nv.horzSubSample = 2;
> +		params_.nv.vertSubSample = 1;
> +		params_.nv.nvSwap = true;
>  		break;
>  	case libcamera::formats::NV24:
>  		formatFamily_ = NV;
> -		horzSubSample_ = 1;
> -		vertSubSample_ = 1;
> -		nvSwap_ = false;
> +		params_.nv.horzSubSample = 1;
> +		params_.nv.vertSubSample = 1;
> +		params_.nv.nvSwap = false;
>  		break;
>  	case libcamera::formats::NV42:
>  		formatFamily_ = NV;
> -		horzSubSample_ = 1;
> -		vertSubSample_ = 1;
> -		nvSwap_ = true;
> +		params_.nv.horzSubSample = 1;
> +		params_.nv.vertSubSample = 1;
> +		params_.nv.nvSwap = true;
>  		break;
>  
>  	case libcamera::formats::RGB888:
>  		formatFamily_ = RGB;
> -		r_pos_ = 2;
> -		g_pos_ = 1;
> -		b_pos_ = 0;
> -		bpp_ = 3;
> +		params_.rgb.r_pos = 2;
> +		params_.rgb.g_pos = 1;
> +		params_.rgb.b_pos = 0;
> +		params_.rgb.bpp = 3;
>  		break;
>  	case libcamera::formats::BGR888:
>  		formatFamily_ = RGB;
> -		r_pos_ = 0;
> -		g_pos_ = 1;
> -		b_pos_ = 2;
> -		bpp_ = 3;
> +		params_.rgb.r_pos = 0;
> +		params_.rgb.g_pos = 1;
> +		params_.rgb.b_pos = 2;
> +		params_.rgb.bpp = 3;
>  		break;
>  	case libcamera::formats::ARGB8888:
>  		formatFamily_ = RGB;
> -		r_pos_ = 2;
> -		g_pos_ = 1;
> -		b_pos_ = 0;
> -		bpp_ = 4;
> +		params_.rgb.r_pos = 2;
> +		params_.rgb.g_pos = 1;
> +		params_.rgb.b_pos = 0;
> +		params_.rgb.bpp = 4;
>  		break;
>  	case libcamera::formats::RGBA8888:
>  		formatFamily_ = RGB;
> -		r_pos_ = 3;
> -		g_pos_ = 2;
> -		b_pos_ = 1;
> -		bpp_ = 4;
> +		params_.rgb.r_pos = 3;
> +		params_.rgb.g_pos = 2;
> +		params_.rgb.b_pos = 1;
> +		params_.rgb.bpp = 4;
>  		break;
>  	case libcamera::formats::ABGR8888:
>  		formatFamily_ = RGB;
> -		r_pos_ = 0;
> -		g_pos_ = 1;
> -		b_pos_ = 2;
> -		bpp_ = 4;
> +		params_.rgb.r_pos = 0;
> +		params_.rgb.g_pos = 1;
> +		params_.rgb.b_pos = 2;
> +		params_.rgb.bpp = 4;
>  		break;
>  	case libcamera::formats::BGRA8888:
>  		formatFamily_ = RGB;
> -		r_pos_ = 1;
> -		g_pos_ = 2;
> -		b_pos_ = 3;
> -		bpp_ = 4;
> +		params_.rgb.r_pos = 1;
> +		params_.rgb.g_pos = 2;
> +		params_.rgb.b_pos = 3;
> +		params_.rgb.bpp = 4;
>  		break;
>  
>  	case libcamera::formats::VYUY:
>  		formatFamily_ = YUV;
> -		y_pos_ = 1;
> -		cb_pos_ = 2;
> +		params_.yuv.y_pos = 1;
> +		params_.yuv.cb_pos = 2;
>  		break;
>  	case libcamera::formats::YVYU:
>  		formatFamily_ = YUV;
> -		y_pos_ = 0;
> -		cb_pos_ = 3;
> +		params_.yuv.y_pos = 0;
> +		params_.yuv.cb_pos = 3;
>  		break;
>  	case libcamera::formats::UYVY:
>  		formatFamily_ = YUV;
> -		y_pos_ = 1;
> -		cb_pos_ = 0;
> +		params_.yuv.y_pos = 1;
> +		params_.yuv.cb_pos = 0;
>  		break;
>  	case libcamera::formats::YUYV:
>  		formatFamily_ = YUV;
> -		y_pos_ = 0;
> -		cb_pos_ = 1;
> +		params_.yuv.y_pos = 0;
> +		params_.yuv.cb_pos = 1;
>  		break;
>  
>  	case libcamera::formats::MJPEG:
> @@ -178,18 +178,20 @@ static void yuv_to_rgb(int y, int u, int v, int *r, int *g, int *b)
>  
>  void FormatConverter::convertNV(const unsigned char *src, unsigned char *dst)
>  {
> -	unsigned int c_stride = width_ * (2 / horzSubSample_);
> -	unsigned int c_inc = horzSubSample_ == 1 ? 2 : 0;
> -	unsigned int cb_pos = nvSwap_ ? 1 : 0;
> -	unsigned int cr_pos = nvSwap_ ? 0 : 1;
> +	unsigned int c_stride = width_ * (2 / params_.nv.horzSubSample);
> +	unsigned int c_inc = params_.nv.horzSubSample == 1 ? 2 : 0;
> +	unsigned int cb_pos = params_.nv.nvSwap ? 1 : 0;
> +	unsigned int cr_pos = params_.nv.nvSwap ? 0 : 1;
>  	const unsigned char *src_c = src + width_ * height_;
>  	int r, g, b;
>  
>  	for (unsigned int y = 0; y < height_; y++) {
>  		const unsigned char *src_y = src + y * width_;
> -		const unsigned char *src_cb = src_c + (y / vertSubSample_) *
> +		const unsigned char *src_cb = src_c +
> +					      (y / params_.nv.vertSubSample) *
>  					      c_stride + cb_pos;
> -		const unsigned char *src_cr = src_c + (y / vertSubSample_) *
> +		const unsigned char *src_cr = src_c +
> +					      (y / params_.nv.vertSubSample) *
>  					      c_stride + cr_pos;
>  
>  		for (unsigned int x = 0; x < width_; x += 2) {
> @@ -223,9 +225,9 @@ void FormatConverter::convertRGB(const unsigned char *src, unsigned char *dst)
>  
>  	for (y = 0; y < height_; y++) {
>  		for (x = 0; x < width_; x++) {
> -			r = src[bpp_ * x + r_pos_];
> -			g = src[bpp_ * x + g_pos_];
> -			b = src[bpp_ * x + b_pos_];
> +			r = src[params_.rgb.bpp * x + params_.rgb.r_pos];
> +			g = src[params_.rgb.bpp * x + params_.rgb.g_pos];
> +			b = src[params_.rgb.bpp * x + params_.rgb.b_pos];
>  
>  			dst[4 * x + 0] = b;
>  			dst[4 * x + 1] = g;
> @@ -233,7 +235,7 @@ void FormatConverter::convertRGB(const unsigned char *src, unsigned char *dst)
>  			dst[4 * x + 3] = 0xff;
>  		}
>  
> -		src += width_ * bpp_;
> +		src += width_ * params_.rgb.bpp;
>  		dst += width_ * 4;
>  	}
>  }
> @@ -246,16 +248,18 @@ void FormatConverter::convertYUV(const unsigned char *src, unsigned char *dst)
>  	unsigned int cr_pos;
>  	int r, g, b, y, cr, cb;
>  
> -	cr_pos = (cb_pos_ + 2) % 4;
> +	cr_pos = (params_.yuv.cb_pos + 2) % 4;
>  	src_stride = width_ * 2;
>  	dst_stride = width_ * 4;
>  
>  	for (src_y = 0, dst_y = 0; dst_y < height_; src_y++, dst_y++) {
>  		for (src_x = 0, dst_x = 0; dst_x < width_; ) {
> -			cb = src[src_y * src_stride + src_x * 4 + cb_pos_];
> +			cb = src[src_y * src_stride + src_x * 4 +
> +				 params_.yuv.cb_pos];
>  			cr = src[src_y * src_stride + src_x * 4 + cr_pos];
>  
> -			y = src[src_y * src_stride + src_x * 4 + y_pos_];
> +			y = src[src_y * src_stride + src_x * 4 +
> +				params_.yuv.y_pos];
>  			yuv_to_rgb(y, cb, cr, &r, &g, &b);
>  			dst[dst_y * dst_stride + 4 * dst_x + 0] = b;
>  			dst[dst_y * dst_stride + 4 * dst_x + 1] = g;
> @@ -263,7 +267,8 @@ void FormatConverter::convertYUV(const unsigned char *src, unsigned char *dst)
>  			dst[dst_y * dst_stride + 4 * dst_x + 3] = 0xff;
>  			dst_x++;
>  
> -			y = src[src_y * src_stride + src_x * 4 + y_pos_ + 2];
> +			y = src[src_y * src_stride + src_x * 4 +
> +				params_.yuv.y_pos + 2];
>  			yuv_to_rgb(y, cb, cr, &r, &g, &b);
>  			dst[dst_y * dst_stride + 4 * dst_x + 0] = b;
>  			dst[dst_y * dst_stride + 4 * dst_x + 1] = g;
> diff --git a/src/qcam/format_converter.h b/src/qcam/format_converter.h
> index e389b24..c53fa28 100644
> --- a/src/qcam/format_converter.h
> +++ b/src/qcam/format_converter.h
> @@ -40,20 +40,29 @@ private:
>  
>  	enum FormatFamily formatFamily_;
>  
> -	/* NV parameters */
> -	unsigned int horzSubSample_;
> -	unsigned int vertSubSample_;
> -	bool nvSwap_;
> -
> -	/* RGB parameters */
> -	unsigned int bpp_;
> -	unsigned int r_pos_;
> -	unsigned int g_pos_;
> -	unsigned int b_pos_;
> -
> -	/* YUV parameters */
> -	unsigned int y_pos_;
> -	unsigned int cb_pos_;
> +	union {
> +		/* NV parameters */
> +		struct nv_params {
> +			unsigned int horzSubSample;
> +			unsigned int vertSubSample;
> +			bool nvSwap;
> +		} nv;
> +
> +		/* RGB parameters */
> +		struct rgb_params {
> +			unsigned int bpp;
> +			unsigned int r_pos;
> +			unsigned int g_pos;
> +			unsigned int b_pos;
> +		} rgb;
> +
> +		/* YUV parameters */
> +		struct yuv_params {
> +			unsigned int y_pos;
> +			unsigned int cb_pos;
> +		} yuv;

The NV* formats are YUV too, we should try to find a better name. It's a
pre-existing issue though.

> +	} params_;

I wonder if it wouldn't make more sense to move all of these to a
separate structure, stored in a map indexed by the pixel format. That
would greatly simplify FormatConverter::configure(). We actually have
such a structure already, PixelFormatInfo, but it's an internal API.
Exposing it as a public API runs into the issue that not all the fields
it contains should be exposed. The V4L2 4CC, for instance, should stay
internal. There's probably a way to handle that, but I'm also no really
keen at this point to committing to a stable API for PixelFormatInfo. I
thus think it would be better to duplicate the data we need here.

To avoid blocking Bayer support in qcam on this, how about moving
forward with patch 2/2 for now without 1/2 ? The small space increase is
negligible.

> +

Extra blank line.

>  };
>  
>  #endif /* __QCAM_FORMAT_CONVERTER_H__ */

-- 
Regards,

Laurent Pinchart


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