linux-kernel - Re: [PATCH] media: vivid: Support 480p for webcam capture

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Date:   Wed, 3 Oct 2018 12:14:22 +0100
From:   Kieran Bingham <kieran.bingham@...asonboard.com>
To:     Keiichi Watanabe <keiichiw@...omium.org>,
        linux-media@...r.kernel.org
Cc:     Hans Verkuil <hverkuil@...all.nl>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        linux-kernel@...r.kernel.org, tfiga@...omium.org,
        jcliang@...omium.org, shik@...omium.org
Subject: Re: [PATCH] media: vivid: Support 480p for webcam capture

Hi Keiichi,

On 03/10/18 08:06, Keiichi Watanabe wrote:
> Support 640x480 as a frame size for video input devices of vivid.
> 
> Signed-off-by: Keiichi Watanabe <keiichiw@...omium.org>
> ---
>  drivers/media/platform/vivid/vivid-vid-cap.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/media/platform/vivid/vivid-vid-cap.c b/drivers/media/platform/vivid/vivid-vid-cap.c
> index 58e14dd1dcd3..da80bf4bc365 100644
> --- a/drivers/media/platform/vivid/vivid-vid-cap.c
> +++ b/drivers/media/platform/vivid/vivid-vid-cap.c
> @@ -51,7 +51,7 @@ static const struct vivid_fmt formats_ovl[] = {
>  };
>  
>  /* The number of discrete webcam framesizes */
> -#define VIVID_WEBCAM_SIZES 5
> +#define VIVID_WEBCAM_SIZES 6
>  /* The number of discrete webcam frameintervals */
>  #define VIVID_WEBCAM_IVALS (VIVID_WEBCAM_SIZES * 2)
>  
> @@ -59,6 +59,7 @@ static const struct vivid_fmt formats_ovl[] = {
>  static const struct v4l2_frmsize_discrete webcam_sizes[VIVID_WEBCAM_SIZES] = {
>  	{  320, 180 },
>  	{  640, 360 },
> +	{  640, 480 },

I agree this is a useful frame size to add...
(having got local patches which also update these tables)

>  	{ 1280, 720 },
>  	{ 1920, 1080 },
>  	{ 3840, 2160 },
> @@ -75,6 +76,8 @@ static const struct v4l2_fract webcam_intervals[VIVID_WEBCAM_IVALS] = {
>  	{  1, 5 },
>  	{  1, 10 },
>  	{  1, 15 },
> +	{  1, 15 },
> +	{  1, 25 },

But won't this add duplicates of 25 and 15 FPS to all the frame sizes
smaller than 1280,720 ? Or are they filtered out?


Now the difficulty is adding smaller frame rates (like 1,1, 1,2) would
effect/reduce the output rates of the larger frame sizes, so how about
adding some high rate support (any two from 1/{60,75,90,100,120}) instead?


Regards

Kieran Bingham

>  	{  1, 25 },
>  	{  1, 30 },
>  	{  1, 50 },
>