Em 28-06-2011 11:23, Michael Jones escreveu:
> There is an assumption that the format coming from the device
> needs 2 bytes per pixel, which is not the case when the device
> delivers e.g. V4L2_PIX_FMT_GREY. This doesn't manifest itself with
> IO_METHOD_MMAP because init_mmap() (the default) doesn't take
> sizeimage as an argument.
>
> Signed-off-by: Michael Jones <[email protected]>
> ---
>
> This same issue would apply to other formats which have 1 byte per pixel,
> this patch only fixes it for GREY. Is this OK for now, or does somebody
> have a better suggestion for supporting other formats as well?
Well, just rely on the bytesperline provided by the driver should be enough.
Devices should be returning it on a consistent way.
Regards,
Mauro
>
> contrib/test/capture-example.c | 4 +++-
> 1 files changed, 3 insertions(+), 1 deletions(-)
>
> diff --git a/contrib/test/capture-example.c b/contrib/test/capture-example.c
> index 3852c58..0eb5235 100644
> --- a/contrib/test/capture-example.c
> +++ b/contrib/test/capture-example.c
> @@ -416,6 +416,7 @@ static void init_device(void)
> struct v4l2_crop crop;
> struct v4l2_format fmt;
> unsigned int min;
> + unsigned int bytes_per_pixel;
>
> if (-1 == xioctl(fd, VIDIOC_QUERYCAP, &cap)) {
> if (EINVAL == errno) {
> @@ -519,7 +520,8 @@ static void init_device(void)
> }
>
> /* Buggy driver paranoia. */
> - min = fmt.fmt.pix.width * 2;
> + bytes_per_pixel = fmt.fmt.pix.pixelformat == V4L2_PIX_FMT_GREY ? 1 : 2;
> + min = fmt.fmt.pix.width * bytes_per_pixel;
> if (fmt.fmt.pix.bytesperline < min)
> fmt.fmt.pix.bytesperline = min;
> min = fmt.fmt.pix.bytesperline * fmt.fmt.pix.height;
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