>
> Hi,
>
> In two nodes case, application cannot know the feature via
> VIDIOC_QUERYCAP.
> Because decoder and encoder return the same CAPABILITY. OUTPUT and CAPTURE
> So application should call VIDIOC_G_FMT to recognize the feature.
The current V4L API is not good enough to determine what each video node
can do. The upcoming media controller API should help in that. For the
time being you should just assume that applications know what they are
doing.
Anyway, I think having two device nodes is a perfectly valid solution.
Particularly for more complex scenarios.
Regards,
Hans
>
> BRs,
>
>> -----Original Message-----
>> From: linux-media-owner@xxxxxxxxxxxxxxx [mailto:linux-media-
>> owner@xxxxxxxxxxxxxxx] On Behalf Of Jonghun Han
>> Sent: Monday, November 29, 2010 8:49 PM
>> To: 'Laurent Pinchart'; 'Hans Verkuil'
>> Cc: jaeryul.oh@xxxxxxxxxxx; linux-media@xxxxxxxxxxxxxxx
>> Subject: RE: RFC: Problem of using v4l2 spec with codec function
>>
>>
>> Laurent Pinchart wrote:
>>
>> > -----Original Message-----
>> > From: linux-media-owner@xxxxxxxxxxxxxxx [mailto:linux-media-
>> > owner@xxxxxxxxxxxxxxx] On Behalf Of Laurent Pinchart
>> > Sent: Monday, November 29, 2010 6:20 PM
>> > To: Hans Verkuil
>> > Cc: jaeryul.oh@xxxxxxxxxxx; linux-media@xxxxxxxxxxxxxxx
>> > Subject: Re: RFC: Problem of using v4l2 spec with codec function
>> >
>> > Hi,
>> >
>> <snip>
>>
>> > > If so, then I think creating a so-called 'private' control for your
>> > > hardware would be the best way to go. As an example of private
>> controls
>> > > search for the V4L2_CID_MPEG_CX2341X_BASE define in videodev2.h.
>> >
>> > I would rely on formats. If the input format is YUV and the output
>> format is
>> > MPEG, it's pretty obvious that the hardware should be encoding. If the
>> formats
>> > are the other way around, then the hardware should be decoding.
>>
>> Right. But..
>> If VIDIOC_S_CTRL is called before VIDIOC_S_FMT, how to distinguish them
>> ?
>> In my opinion decoder and encoder can have own control Ids.
>> For example,
>> After VIDIOC_S_CTRL related in decoder, if VIDIOC_S_FMT for encoder is
>> called
>> how to return it ?
>> VIDIOC_S_CTRL has been succeeded because driver cannot know whether
>> decoder or encoder.
>> And then is it right that VIDIOC_S_FMT for encoder is failed due to
>> VIDIOC_S_CTRL for decoder ?
>>
>> Can two nodes(encoder, decoder) be the solution ?
>>
>> BRs,
>>
>> > --
>> > Regards,
>> >
>> > Laurent Pinchart
>> > --
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>>
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>
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--
Hans Verkuil - video4linux developer - sponsored by Cisco
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