Hi Ming,
On 12/14/2011 04:57 PM, Ming Lei wrote:
> Hi,
>
> On Wed, Dec 14, 2011 at 11:34 PM, Sakari Ailus <sakari.ailus@xxxxxx> wrote:
>
>>> + case VIDIOC_G_FD_RESULT:
>>> + {
>>> + struct v4l2_fd_result *fr = arg;
>>> +
>>> + if (!ops->vidioc_g_fd_result)
>>> + break;
>>> +
>>> + ret = ops->vidioc_g_fd_result(file, fh, fr);
>>> +
>>> + dbgarg(cmd, "index=%d", fr->buf_index);
>>> + break;
>>> + }
>>> + case VIDIOC_G_FD_COUNT:
>>> + {
>>> + struct v4l2_fd_count *fc = arg;
>>> +
>>> + if (!ops->vidioc_g_fd_count)
>>> + break;
>>> +
>>> + ret = ops->vidioc_g_fd_count(file, fh, fc);
>>> +
>>> + dbgarg(cmd, "index=%d", fc->buf_index);
>>> + break;
>>> + }
>>
>> The patch description tells these ioctls may be called between... what? I'd
>
> In fact, these ioctls should be called after return from poll.
>
>> think such information could be better provided as events.
>
> Yes, I still think so, but the length of returned data is variant, also
> event has the 64 byte length's limitation.
Right, I'm afraid it's not even enough for single object description.
I have been thinking about adding variable payload support to v4l2 event API.
>> How is face detection enabled or disabled?
>
> Currently, streaming on will trigger detection enabling, and streaming off
> will trigger detection disabling.
We would need to develop a boolean control for this I think, this seems one of
the basic features for the configuration interface.
>> Could you detect other objects than faces?
>
> The -v2 has been extended to detect objects, not limited to faces.
>
>> Would events be large enough to deliver you the necessary data? We could
>
> Looks like event(64 bytes) is not large enough to deliver the data.
>
>> also consider delivering the information as a data structure on a separate
>> plane.
>
> Could you let me know how to do it?
You would have to use multi-planar interface for that, which would introduce
additional complexity at user interface. Moreover variable plane count is not
supported in vb2. Relatively significant effort is required to add this IMHO.
--
Regards,
Sylwester
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