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Message-ID: <4EDD428B.9010800@gmail.com>
Date: Mon, 05 Dec 2011 23:15:39 +0100
From: Sylwester Nawrocki <snjw23@...il.com>
To: Ming Lei <ming.lei@...onical.com>
CC: linux-omap@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
linux-kernel@...r.kernel.org, linux-media@...r.kernel.org
Subject: Re: [RFC PATCH v1 5/7] media: v4l2: introduce two IOCTLs for face
detection
On 12/02/2011 04:02 PM, Ming Lei wrote:
> This patch introduces two new IOCTLs and related data
> structure defination which will be used by the coming
> face detection video device.
>
> The two IOCTLs and related data structure are used by
> user space application to retrieve the results of face
> detection. They can be called after one v4l2_buffer
> has been ioctl(VIDIOC_DQBUF) and before it will be
> ioctl(VIDIOC_QBUF).
>
> The utility fdif[1] is useing the two IOCTLs to find
> faces deteced in raw images or video streams.
>
> [1],http://kernel.ubuntu.com/git?p=ming/fdif.git;a=shortlog;h=refs/heads/v4l2-fdif
>
> Signed-off-by: Ming Lei <ming.lei@...onical.com>
> ---
> drivers/media/video/v4l2-ioctl.c | 38 ++++++++++++++++++++
> include/linux/videodev2.h | 70 ++++++++++++++++++++++++++++++++++++++
> include/media/v4l2-ioctl.h | 6 +++
> 3 files changed, 114 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/media/video/v4l2-ioctl.c b/drivers/media/video/v4l2-ioctl.c
> index e1da8fc..fc6266f 100644
> --- a/drivers/media/video/v4l2-ioctl.c
> +++ b/drivers/media/video/v4l2-ioctl.c
> @@ -2140,6 +2140,30 @@ static long __video_do_ioctl(struct file *file,
> dbgarg(cmd, "index=%d", b->index);
> break;
> }
> + case VIDIOC_G_FD_RESULT:
> + {
> + struct v4l2_fd_result *fr = arg;
> +
> + if (!ops->vidioc_g_fd_result)
> + break;
> +
> + ret = ops->vidioc_g_fd_result(file, fh, fr);
> +
> + dbgarg(cmd, "index=%d", fr->buf_index);
> + break;
> + }
> + case VIDIOC_G_FD_COUNT:
> + {
> + struct v4l2_fd_count *fc = arg;
> +
> + if (!ops->vidioc_g_fd_count)
> + break;
> +
> + ret = ops->vidioc_g_fd_count(file, fh, fc);
> +
> + dbgarg(cmd, "index=%d", fc->buf_index);
> + break;
> + }
> default:
> if (!ops->vidioc_default)
> break;
> @@ -2234,6 +2258,20 @@ static int check_array_args(unsigned int cmd, void *parg, size_t *array_size,
> }
> break;
> }
> +
> + case VIDIOC_G_FD_RESULT: {
> + struct v4l2_fd_result *fr = parg;
> +
> + if (fr->face_cnt != 0) {
> + *user_ptr = (void __user *)fr->fd;
> + *kernel_ptr = (void *)&fr->fd;
> + *array_size = sizeof(struct v4l2_fd_detection)
> + * fr->face_cnt;
> + ret = 1;
> + }
> + break;
> +
> + }
> }
>
> return ret;
> diff --git a/include/linux/videodev2.h b/include/linux/videodev2.h
> index 4b752d5..073eb4d 100644
> --- a/include/linux/videodev2.h
> +++ b/include/linux/videodev2.h
> @@ -2160,6 +2160,74 @@ struct v4l2_create_buffers {
> __u32 reserved[8];
> };
>
> +/**
> + * struct v4l2_obj_detection
> + * @buf_index: entry, index of v4l2_buffer for face detection
> + * @centerx: return, position in x direction of detected object
> + * @centery: return, position in y direction of detected object
> + * @angle: return, angle of detected object
> + * 0 deg ~ 359 deg, vertical is 0 deg, clockwise
> + * @sizex: return, size in x direction of detected object
> + * @sizey: return, size in y direction of detected object
> + * @confidence: return, confidence level of detection result
> + * 0: the heighest level, 9: the lowest level
Hmm, not a good idea to align a public interface to the capabilities
of a single hardware implementation. min/max confidence could be queried with
relevant controls and here we could remove the line implying range.
> + * @reserved: future extensions
> + */
> +struct v4l2_obj_detection {
> + __u16 centerx;
> + __u16 centery;
> + __u16 angle;
> + __u16 sizex;
> + __u16 sizey;
How about using struct v4l2_rect in place of centerx/centery, sizex/sizey ?
After all it describes a rectangle. We could also use struct v4l2_frmsize_discrete
for size but there seems to be missing en equivalent for position, e.g.
struct v4l2_position {
__s32 x;
__s32 y;
};
> + __u16 confidence;
> + __u32 reserved[4];
> +};
> +
> +#define V4L2_FD_HAS_LEFT_EYE 0x1
> +#define V4L2_FD_HAS_RIGHT_EYE 0x2
> +#define V4L2_FD_HAS_MOUTH 0x4
> +#define V4L2_FD_HAS_FACE 0x8
> +
> +/**
> + * struct v4l2_fd_detection - VIDIOC_G_FD_RESULT argument
> + * @flag: return, describe which objects are detected
> + * @left_eye: return, left_eye position if detected
> + * @right_eye: return, right_eye position if detected
> + * @mouth_eye: return, mouth_eye position if detected
mouth_eye ? ;)
> + * @face: return, face position if detected
> + */
> +struct v4l2_fd_detection {
> + __u32 flag;
> + struct v4l2_obj_detection left_eye;
> + struct v4l2_obj_detection right_eye;
> + struct v4l2_obj_detection mouth;
> + struct v4l2_obj_detection face;
I would do this differently, i.e. put "flag" inside struct v4l2_obj_detection
and then struct v4l2_fd_detection would be simply an array of
struct v4l2_obj_detection, i.e.
struct v4l2_fd_detection {
unsigned int count;
struct v4l2_obj_detection [V4L2_MAX_FD_OBJECT_NUM];
};
This might be more flexible, e.g. if in the future some hardware supports
detecting wrinkles, we could easily add that by just defining a new flag:
V4L2_FD_HAS_WRINKLES, etc.
--
Regards,
Sylwester
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