RE: [RFC v4] Multi-plane buffer support for V4L2 API

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



Hi Mauro,

thanks for taking the time to look at this.

>Mauro Carvalho Chehab <mchehab@xxxxxxxxxx> wrote:
>
>With Hans proposed changes that you've already acked, I think the proposal is
>ok,
>except for one detail:
>
>> 4. Format enumeration
>> ----------------------------------
>> struct v4l2_fmtdesc, used for format enumeration, does include the
>v4l2_buf_type
>> enum as well, so the new types can be handled properly here as well.
>> For drivers supporting both versions of the API, 1-plane formats should be
>> returned for multiplanar buffer types as well, for consistency. In other
>words,
>> for multiplanar buffer types, the formats returned are a superset of those
>> returned when enumerating with the old buffer types.
>>
>
>We shouldn't mix types here. If the userspace is asking for multi-planar
>types,
>the driver should return just the multi-planar formats.
>
>If the userspace wants to know about both, it will just call for both types
>of
>formats.

Yes. Although the idea here is that we wanted to be able to use single-planar
formats with either the old API or the new multiplane API. In the new API, you
could just set num_planes=1.

So multiplanar API != multiplanar format. When you enum_fmt for mutliplanar
types, you get "all formats you can use with the multiplanar API" and not
"all formats that have num_planes > 1".

This can simplify applications - they don't have to switch between APIs when
switching between formats. They may even choose not to use the old API at all
(if a driver allows it).

Do we want to lose the ability to use multiplanar API for single-plane
formats?

Best regards
--
Pawel Osciak
Linux Platform Group
Samsung Poland R&D Center





--
To unsubscribe from this list: send the line "unsubscribe linux-media" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html


[Index of Archives]     [Linux Input]     [Video for Linux]     [Gstreamer Embedded]     [Mplayer Users]     [Linux USB Devel]     [Linux Audio Users]     [Linux Kernel]     [Linux SCSI]     [Yosemite Backpacking]
  Powered by Linux