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

[Laurent Pinchart]

Hi David,

On Thu, Jun 18, 2020 at 01:18:21AM +0300, Laurent Pinchart wrote:
> 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).
> 
> But only if cameras can provide them :-)
> 
> Does the Raspberry Pi ISP support both V4L2_PIX_FMT_YUV420 and
> V4L2_PIX_FMT_YUV422P ? I see mentions of the former in the driver, but
> not of the latter.
> 
> > 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,
> > +	} },

I may merge in the morning a patch series that rework format handling
and would conflict with this patch. If that's the case, I'll rebase this
patch and send the rebased version to the list.

> >  
> >  	/* 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 } }} },

Additionally, don't those formats have 3 planes, not two ?

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

-- 
Regards,

Laurent Pinchart