Hi Sylwester,
On Fri, Jun 14, 2013 at 3:23 PM, Sylwester Nawrocki
<s.nawrocki@xxxxxxxxxxx> wrote:
> Hi Arun,
>
> On 06/14/2013 11:26 AM, Arun Kumar K wrote:
>> Hi Sylwester,
>>
>>>> + static const char * const vpx_num_partitions[] = {
>>>> + "1 partition",
>>>> + "2 partitions",
>>>> + "4 partitions",
>>>> + "8 partitions",
>>>> + NULL,
>>>> + };
>>>> + static const char * const vpx_num_ref_frames[] = {
>>>> + "1 reference frame",
>>>> + "2 reference frame",
>>>> + NULL,
>>>> + };
>>>
>>> Have you considered using V4L2_CTRL_TYPE_INTEGER_MENU control type for this ?
>>> One example is V4L2_CID_ISO_SENSITIVITY control.
>>>
>>
>> If I understand correctly, V4L2_CTRL_TYPE_INTEGER_MENU is used for
>> controls where
>> the driver / IP can support different values depending on its capabilities.
>
> No, not really, it just happens there is no INTEGER_MENU control with standard
> values yet. I think there are some (minor) changes needed in the v4l2-ctrls
> code to support INTEGER_MENU control with standard menu items.
>
>> But here VP8 standard supports only 4 options for no. of partitions
>> that is 1, 2, 4 and 8.
>
> I think such a standard menu list should be defined in v4l2-ctrls.c then.
One more concern here is these integer values 1, 2, 4 and 8 may not hold
much significance while setting to the registers. Some IPs may need these
values to be set as 0, 1, 2 and 3. So unlike other settings like ISO, the
values that are given by the user may not be directly applicable to the
register setting.
>
>> Also for number of ref frames, the standard allows only the options 1,
>> 2 and 3 which
>> cannot be extended more. So is it correct to use INTEGER_MENU control here and
>> let the driver define the values?
>
> If this is standard then the core should define available menu items. But
> it seems more appropriate for me to use INTEGER_MENU. I'd like to hear other
> opinions though.
Here even though 1,2 and 3 are standard, the interpretation is
1 - 1 reference frame (previous frame)
2 - previous frame + golden frame
3 - previous frame + golden frame + altref frame.
Again the driver may need to set different registers based on these and the
integer values as such may not be used.
Regards
Arun
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