[libcamera-devel] [PATCH v2 1/6] libcamera: bayer_format: Add a toPixelFormat() helpers to the BayerFormat class

[Naushir Patuck]

Hi Laurent,

On Tue, 26 Oct 2021 at 08:48, Naushir Patuck <naush at raspberrypi.com> wrote:

> Hi Laurent,
>
> Thank you for your feedback.
>
> On Mon, 25 Oct 2021 at 14:58, Laurent Pinchart <
> laurent.pinchart at ideasonboard.com> wrote:
>
>> Hi Naush,
>>
>> Thank you for the patch.
>>
>> On Fri, Oct 22, 2021 at 03:39:02PM +0100, Naushir Patuck wrote:
>> > Add a BayerFormat::toPixelFormat() member function to convert a
>> BayerFormat to a
>> > PixelFormat type. This conversion uses the existing bayerToV4l2
>> conversion
>> > table.
>> >
>> > Signed-off-by: Naushir Patuck <naush at raspberrypi.com>
>> > Reviewed-by: David Plowman <david.plowman at raspberrypi.com>
>> > ---
>> >  include/libcamera/internal/bayer_format.h |  3 +++
>> >  src/libcamera/bayer_format.cpp            | 13 +++++++++++++
>> >  2 files changed, 16 insertions(+)
>> >
>> > diff --git a/include/libcamera/internal/bayer_format.h
>> b/include/libcamera/internal/bayer_format.h
>> > index 723382d4168d..247a60cf0e36 100644
>> > --- a/include/libcamera/internal/bayer_format.h
>> > +++ b/include/libcamera/internal/bayer_format.h
>> > @@ -10,6 +10,8 @@
>> >  #include <stdint.h>
>> >  #include <string>
>> >
>> > +#include <libcamera/pixel_format.h>
>> > +
>> >  #include "libcamera/internal/v4l2_pixelformat.h"
>> >
>> >  namespace libcamera {
>> > @@ -50,6 +52,7 @@ public:
>> >
>> >       V4L2PixelFormat toV4L2PixelFormat() const;
>> >       static BayerFormat fromV4L2PixelFormat(V4L2PixelFormat
>> v4l2Format);
>> > +     PixelFormat toPixelFormat() const;
>> >       BayerFormat transform(Transform t) const;
>> >
>> >       Order order;
>> > diff --git a/src/libcamera/bayer_format.cpp
>> b/src/libcamera/bayer_format.cpp
>> > index 11355f144f66..c662ba36604c 100644
>> > --- a/src/libcamera/bayer_format.cpp
>> > +++ b/src/libcamera/bayer_format.cpp
>> > @@ -269,6 +269,19 @@ BayerFormat
>> BayerFormat::fromV4L2PixelFormat(V4L2PixelFormat v4l2Format)
>> >       return BayerFormat();
>> >  }
>> >
>> > +/**
>> > + * \brief Convert a BayerFormat into the corresponding PixelFormat
>> > + * \return The PixelFormat corresponding to this BayerFormat
>> > + */
>> > +PixelFormat BayerFormat::toPixelFormat() const
>> > +{
>> > +     const auto it = bayerToV4l2.find(*this);
>> > +     if (it != bayerToV4l2.end())
>> > +             return PixelFormat(it->second);
>>
>> Should we store the PixelFormat in the bayerToV4l2 map to avoid a double
>> looking (one here, one in the PixelFormat constructor) ? The map should
>> be renamed to bayerToFormat, and be stored as either
>>
>> std::map<BayerFormat, std::pair<PixelFormat, V4L2PixelFormat>,
>> BayerFormatComparator>
>>
>> or
>>
>> struct Formats {
>>         PixelFormat pixelFormat;
>>         V4L2PixelFormat v4l2Format;
>> };
>>
>> std::map<BayerFormat, Formats, BayerFormatComparator>
>>
>
> This seems reasonable.  I will update the table with a std::pair for 2-way
> conversion.
>

Unfortunately this has hit an unexpected complication.  DRM formats, and
subsequently
PixelFormat types do not define Mono Bayer formats.  The corresponding mbus
codes
are MEDIA_BUS_FMT_Y8_1X8 and MEDIA_BUS_FMT_Y10_1X10.

Would it be acceptable if the conversion regards these mono BayerFormat
types as invalid
PixelFormat types with a todo to add appropriate support in the future?
Mono sensor support
is still usable as we go from mbus code -> V4L2 4CC correctly, but the
application can never
request a mono output - which it can't do today anyway!

Naush
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