[libcamera-devel] [PATCH v2 1/5] define Span size as shape vector

[Laurent Pinchart]

Hi Christian,

Thank you for the patch.

The subject line should be

libcamera: controls: Define size of array controls as a shape vector

(for the right prefix, and because you're modifying controls, not the
Span class)

On Tue, Apr 05, 2022 at 01:42:11AM +0100, Christian Rauch via libcamera-devel wrote:
> This follows the convention in other Tensor APIs. Since all tensors are
> represented as a Span with a single dimension, values provided in 'size'
> are interpreted as fixed-size Spans, while an empty array ("[]") will be
> interpreted as variable-sized Span.

In tensorflow notation (and I suppose other tensor APIs), the [] shape
describes a scalar. Should we keep "n" to denote a variable number of
elements, but still apply the change that uses the comma as a separator
instead of the 'x' ? Otherwise a variable-length array of objects that
have three components would have "[3,]" as a shape, which looks quite
weird.

There may be alternatives, such as using "*" instead of "n" for
instance. I don't know if there's any standard(ish) notation.

> Signed-off-by: Christian Rauch <Rauch.Christian at gmx.de>
> ---
>  src/libcamera/control_ids.yaml  | 2 +-
>  src/libcamera/property_ids.yaml | 4 ++--
>  2 files changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/src/libcamera/control_ids.yaml b/src/libcamera/control_ids.yaml
> index 9d4638ae..c3f593a1 100644
> --- a/src/libcamera/control_ids.yaml
> +++ b/src/libcamera/control_ids.yaml
> @@ -291,7 +291,7 @@ controls:
>          transformation. The 3x3 matrix is stored in conventional reading
>          order in an array of 9 floating point values.
> 
> -      size: [3x3]
> +      size: [3,3]
> 
>    - ScalerCrop:
>        type: Rectangle
> diff --git a/src/libcamera/property_ids.yaml b/src/libcamera/property_ids.yaml
> index 12ecbce5..47c350ed 100644
> --- a/src/libcamera/property_ids.yaml
> +++ b/src/libcamera/property_ids.yaml
> @@ -497,7 +497,7 @@ controls:
> 
>    - PixelArrayOpticalBlackRectangles:
>        type: Rectangle
> -      size: [n]
> +      size: []
>        description: |
>          The pixel array region(s) which contain optical black pixels
>          considered valid for calibration purposes.
> @@ -592,7 +592,7 @@ controls:
> 
>    - PixelArrayActiveAreas:
>        type: Rectangle
> -      size: [n]
> +      size: []
>        description: |
>          The PixelArrayActiveAreas property defines the (possibly multiple and
>          overlapping) portions of the camera sensor readable pixel matrix

-- 
Regards,

Laurent Pinchart