[libcamera-devel] [PATCH] libcamera: add support for planar YUV422 and YUV420 formats

[Laurent Pinchart]

Hi David,

On Wed, Jun 17, 2020 at 05:44:42PM +0100, David Plowman wrote:
> These formats can be helpful when downstream applications or libraries
> support them natively (avoiding a costly conversion).
> 
> Signed-off-by: David Plowman <david.plowman at raspberrypi.com>
> ---
>  src/libcamera/formats.cpp          | 14 ++++++++++++++
>  src/libcamera/v4l2_pixelformat.cpp |  2 ++
>  src/v4l2/v4l2_camera_proxy.cpp     |  2 ++
>  3 files changed, 18 insertions(+)
> 
> diff --git a/src/libcamera/formats.cpp b/src/libcamera/formats.cpp
> index 2ac3b41..dcd1dcf 100644
> --- a/src/libcamera/formats.cpp
> +++ b/src/libcamera/formats.cpp
> @@ -268,6 +268,20 @@ const std::map<PixelFormat, PixelFormatInfo> pixelFormatInfo{
>  		.colourEncoding = PixelFormatInfo::ColourEncodingYUV,
>  		.packed = false,
>  	} },
> +	{ PixelFormat(DRM_FORMAT_YUV422), {
> +		.format = PixelFormat(DRM_FORMAT_YUV422),
> +		.v4l2Format = V4L2PixelFormat(V4L2_PIX_FMT_YUV422P),
> +		.bitsPerPixel = 16,
> +		.colourEncoding = PixelFormatInfo::ColourEncodingYUV,
> +		.packed = false,
> +	} },
> +	{ PixelFormat(DRM_FORMAT_YUV420), {
> +		.format = PixelFormat(DRM_FORMAT_YUV420),
> +		.v4l2Format = V4L2PixelFormat(V4L2_PIX_FMT_YUV420),
> +		.bitsPerPixel = 12,
> +		.colourEncoding = PixelFormatInfo::ColourEncodingYUV,
> +		.packed = false,
> +	} },
>  
>  	/* Greyscale formats. */
>  	{ PixelFormat(DRM_FORMAT_R8), {
> diff --git a/src/libcamera/v4l2_pixelformat.cpp b/src/libcamera/v4l2_pixelformat.cpp
> index 94fae47..01778c0 100644
> --- a/src/libcamera/v4l2_pixelformat.cpp
> +++ b/src/libcamera/v4l2_pixelformat.cpp
> @@ -64,6 +64,8 @@ const std::map<V4L2PixelFormat, PixelFormat> vpf2pf{
>  	{ V4L2PixelFormat(V4L2_PIX_FMT_NV61), PixelFormat(DRM_FORMAT_NV61) },
>  	{ V4L2PixelFormat(V4L2_PIX_FMT_NV12), PixelFormat(DRM_FORMAT_NV12) },
>  	{ V4L2PixelFormat(V4L2_PIX_FMT_NV21), PixelFormat(DRM_FORMAT_NV21) },
> +	{ V4L2PixelFormat(V4L2_PIX_FMT_YUV422P), PixelFormat(DRM_FORMAT_YUV422) },
> +	{ V4L2PixelFormat(V4L2_PIX_FMT_YUV420), PixelFormat(DRM_FORMAT_YUV420) },
>  
>  	/* Greyscale formats. */
>  	{ V4L2PixelFormat(V4L2_PIX_FMT_GREY), PixelFormat(DRM_FORMAT_R8) },
> diff --git a/src/v4l2/v4l2_camera_proxy.cpp b/src/v4l2/v4l2_camera_proxy.cpp
> index d7f14e6..a54d47e 100644
> --- a/src/v4l2/v4l2_camera_proxy.cpp
> +++ b/src/v4l2/v4l2_camera_proxy.cpp
> @@ -576,6 +576,8 @@ static const std::array<PixelFormatInfo, 14> pixelFormatInfo = {{
>  	{ PixelFormat(DRM_FORMAT_NV61),		V4L2_PIX_FMT_NV61,	2, {{ {  8, 1, 1 }, { 16, 2, 1 }, {  0, 0, 0 } }} },
>  	{ PixelFormat(DRM_FORMAT_NV24),		V4L2_PIX_FMT_NV24,	2, {{ {  8, 1, 1 }, { 16, 1, 1 }, {  0, 0, 0 } }} },
>  	{ PixelFormat(DRM_FORMAT_NV42),		V4L2_PIX_FMT_NV42,	2, {{ {  8, 1, 1 }, { 16, 1, 1 }, {  0, 0, 0 } }} },
> +	{ PixelFormat(DRM_FORMAT_YUV422),	V4L2_PIX_FMT_YUV422P,	2, {{ {  8, 1, 1 }, { 8, 2, 1 }, {  8, 2, 1 } }} },
> +	{ PixelFormat(DRM_FORMAT_YUV420),	V4L2_PIX_FMT_YUV420,	2, {{ {  8, 1, 1 }, { 8, 2, 2 }, {  8, 2, 2 } }} },

This causes a compilation error, as the array is defined with a fixed
number of elements. Could you make sure to enable compilation of the
V4L2 compatibility layer to develop patches that touches it ? It's
disabled by default, and you can enable it by running

	meson configure -Dv4l2=true

in the build directory. Same for the Android compatibility layer, with
-Dandroid=true if you author patches that impact it. I enable both in
all my builds, just in case.

>  	/* Compressed formats. */
>  	/*
>  	 * \todo Get a better image size estimate for MJPEG, via

-- 
Regards,

Laurent Pinchart