Date:   Mon, 8 Oct 2018 10:47:48 +0100
From:   Kieran Bingham <kieran.bingham@...asonboard.com>
To:     Hans Verkuil <hverkuil@...all.nl>,
        Keiichi Watanabe <keiichiw@...omium.org>
Cc:     Linux Media Mailing List <linux-media@...r.kernel.org>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Tomasz Figa <tfiga@...omium.org>,
        Ricky Liang <jcliang@...omium.org>,
        Shik Chen <shik@...omium.org>
Subject: Re: [PATCH] media: vivid: Support 480p for webcam capture

On 08/10/18 10:00, Hans Verkuil wrote:
> On 10/08/2018 10:35 AM, Kieran Bingham wrote:
>> On 06/10/18 11:29, Keiichi Watanabe wrote:
>>> Hi all,
>>>
>>> On Fri, Oct 5, 2018 at 6:18 PM, Hans Verkuil <hverkuil@...all.nl> wrote:
>>>> On 10/03/18 09:08, Keiichi Watanabe wrote:
>>>>> I think 480p is a common frame size and it's worth supporting in vivid.
>>>>> But, my patch might be ad-hoc. Actually, I'm not sure which values are
>>>>> suitable for the intervals.
>>>>
>>>> I can apply this ad-hoc patch as-is.
>>>>
>>>> Or do you want to postpone this and work on a more generic solution?
>>>> Although I am not sure what that would look like.
>>>
>>> I prefer providing a more flexible way rather than this ad-hoc patch.
>>> It would be helpful if there is a way of changing supported frame sizes easily.
>>> Perhaps, Kieran and me would use it, at least:)
>>>
>>
>> o/ <raising hand in agreement>
>>
>>>>
>>>> Proposals are welcome!
>>>>
>>>> The main purpose of this code is to have something that kind of acts like
>>>> a real webcam that has various resolutions, and a slower framerate for
>>>> higher resolutions (as you would expect).
>>>
>>> This sounds reasonable, so I guess we can keep this way as default and
>>> provide a way for specifying extra frame sizes as an option.
>>>
>>> For example, how about a module option like this?
>>> "webcam_sizes=640x480@15,320x240@30"
>>>
>>> If this parameter is passed to vivid, vivid works like a webcam that
>>> supports the following 7 pairs of frame size and fps:
>>> - 5 pairs of frame sizes and fps, as with the current implementation
>>> - 640x480 (15fps)
>>> - 320x240 (30fps)
>>
>> I like the concept of being able to specify as a module parameter.
>>
>> Perhaps we could have a magic marker on the string to define if the
>> existing frame sizes should be kept - or if this is just a complete
>> override ?
> 
> No, just override. It's hard otherwise since you would have to keep the
> lists sorted by resolution/fps.
> 
> If you want to set it yourself, then just do a complete override.

OK. That's reasonable for me.

 @@ -9,3 +9,0 @@ suggestion
 - magic-marker


>>  vivid.webcam=640x480@15,320x240@30  # Specify sizes explicitly
>>  vivid.webcam=+640x480@15,320x240@30  # Append to existing frames
>>               ^ Magic Marker
>>
>> We might of course want multiple rates per frame,
>>
>>  vivid.webcam=640x480@...25-30-90-120, # Separator to be defined...
> 
> Stick to @, so: vivid.webcam=640x480@15@25@30@90@120

Yes, of course that makes a lot more sense now I see it :-)

--
Kieran


> This looks like a good proposal to me.
> 
> BTW, I still would like to add 640x480 added to the default list:
> it's a common resolution and it makes sense to add it.
> 
> So I plan to accept the patch regardless.
> 
> Regards,
> 
> 	Hans
> 
>>
>>
>>>
>>> If this parameter is not passed, vivid's behavior won't change from
>>> the current one.
>>>
>>> How do you think?
>>>
>>> We might want to stop using the default framesizes, i.e. vivid only
>>> supports framesize/fps that passed as the option.
>>> But, if we do so, the parameter will become mandatory and it would be annoying.
>>
>> I think mandatory would be annoying yes.
>>
>> Thus my suggestion for a magic marker above :)
>>
>> --
>> Kieran
>>
>>
>>> So, I personally like to keep the default framesizes.
>>>
>>> Best regards,
>>> Kei
>>>
>>>>
>>>> Regards,
>>>>
>>>>         Hans
>>>>
>>>>>
>>>>> We might want to add a more flexible/extensible way to specify frame sizes.
>>>>> e.g. passing frame sizes and intervals as module parameters
>>>>>
>>>>> Kei
>>>>>
>>>>> On Wed, Oct 3, 2018 at 4:06 PM, Keiichi Watanabe <keiichiw@...omium.org> 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 },
>>>>>>         { 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 },
>>>>>>         {  1, 25 },
>>>>>>         {  1, 30 },
>>>>>>         {  1, 50 },
>>>>>> --
>>>>>> 2.19.0.605.g01d371f741-goog
>>>>>>
>>>>
>>
>>
> 

-- 
Regards
--
Kieran

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