[libcamera-devel] [PATCH] v4l2: v4l2_camera_proxy: Fix timestamp calculation

[Laurent Pinchart]

Hi Kieran,

Thank you for the patch.

On Mon, Feb 14, 2022 at 12:39:51PM +0000, Kieran Bingham wrote:
> The V4L2 Compatibility layer is returning timestamps for buffers which
> are incorrectly calculated from the frame metadata.
> 
> The sec component of the timestamp is correct, but the nsec component is

Did you mean usec ?

> out, leaving frame captures reporting non-monotonically increasing
> timestamps, and incorrect frame rate calculations.
> 
> Fix the usecs calculation reported by the V4L2 adaptation layer.
> 
> Bug: https://bugs.libcamera.org/show_bug.cgi?id=118
> Fixes: 0ce8f2390b52 ("v4l2: v4l2_compat: Add V4L2 compatibility layer")
> Signed-off-by: Kieran Bingham <kieran.bingham at ideasonboard.com>
> ---
>  src/v4l2/v4l2_camera_proxy.cpp | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/src/v4l2/v4l2_camera_proxy.cpp b/src/v4l2/v4l2_camera_proxy.cpp
> index 45822feff317..67b2c50c0f7e 100644
> --- a/src/v4l2/v4l2_camera_proxy.cpp
> +++ b/src/v4l2/v4l2_camera_proxy.cpp
> @@ -234,7 +234,7 @@ void V4L2CameraProxy::updateBuffers()
>  							});
>  			buf.field = V4L2_FIELD_NONE;
>  			buf.timestamp.tv_sec = fmd.timestamp / 1000000000;
> -			buf.timestamp.tv_usec = fmd.timestamp % 1000000;
> +			buf.timestamp.tv_usec = fmd.timestamp / 1000 % 1000000;

I'd have written

			buf.timestamp.tv_usec = (fmd.timestamp / 1000) % 1000000;

Reviewed-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>

either way.

>  			buf.sequence = fmd.sequence;
>  
>  			buf.flags |= V4L2_BUF_FLAG_DONE;

-- 
Regards,

Laurent Pinchart