In USB webcam AVStream minidriver, how to return extension unit information?

Question

In my USB webcam AVStream minidriver, I need to return UVC extension unit information defined in H264 UVC spec.

For control selector UVCX_VIDEO_CONFIG_PROBE, its current, default, min and max values are stored in a 46 bytes structure. So, KSPROPERTY_STEPPING_LONG cannot be used.

Please advise how to fill in KSPROPERTY_VALUES of KSPROPERTY_ITEM for UVCX_VIDEO_CONFIG_PROBE so that applications can get its informations (default, min and max). Thanks. 

Answer 1

Windows UVC driver starts to support H.264 since Windows 8.

check this:

http://msdn.microsoft.com/en-us/library/windows/hardware/ff568651(v=vs.85).aspx

UVC Version	Windows   Vista/XP	Windows 7	Windows 8   Consumer Preview
USB Video Class 1.2 (H.264 video   codec)	Not supported	Not supported	Supported
USB   Video Class 1.1	Not   supported	Supported	Supported
USB   Video Class 1.0	Supported	Supported	Supported

Answer 2

Hi Fred,

Thanks for your reply.

First of all, please forget H264 stuff in my query.

I am currently writing my own USB webcam AVStream minidriver.

As you know, for a normal property like brightness, we use KSPROPERTY_STEPPING_LONG to return step, min and max values. And they are defined as LONG or LONLONG in the MSDN.

For a property to return step, min or max values which are more than 8 bytes, there is no explanation in MSDN on how to do so.

Please help to let me know where I can find relevant information. Thanks.

Answer 3

Bigstone10 wrote:

>

>?I am currently writing my own USB webcam AVStream minidriver.

>

>As you know, for a normal property like brightness, we use

>KSPROPERTY_STEPPING_LONG to return step, min and max values.

>And they are defined as LONG or LONLONG in the MSDN.

>

>For a property to return step, min or max values which are

>more than 8 bytes, there is no explanation in MSDN on how to do so.

 

You do not use a KSPROPERTY_VALUES array for something like that.  The

stepping things are just a shortcut for small integer property values that

have distinct values.

 

For irregular properties, you set the Values item to NULL.  You set

MinProperty and MinData to the actual sizes, and you do all of the

validation in your Set handler.

--

Tim Roberts, [e-mail]

Providenza & Boekelheide, Inc.

 

---

Tim Roberts, VC++ MVP Providenza & Boekelheide, Inc.

Answer 4

Hi Tim,

Thanks for your advise.

I tried to use SupportHandler before. But I do not know how to return step, min and max values when BASICSUPPORT is received.

I tried to return as 3 consecutive values. So I copy the step, min and max values in the memory received, but it does not work.

Can you please further advise me on how to fill in KSPROPERTY_DESCRIPTION and KSPROPERTY_MEMBERSHEADER for BASICSUPPORT?

Your help is greatly appreciated.

 

Answer 5

Bigstone10 wrote:

>

>I tried to use SupportHandler before. But I do not know how to return step,

>min and max values when BASICSUPPORT is received.

>

>Can you please further advise me on how to fill in KSPROPERTY_DESCRIPTION

>and KSPROPERTY_MEMBERSHEADER for BASICSUPPORT?

 

YOU DON'T HAVE TO DO THIS.

 

When you create your KSPROPERTY_ITEM, define a GetHandler and/or a

SetHandler.  Set the MinData member to the size of your data.  Set the

Values member to NULL.  The framework will handle the BASICSUPPORT call for

you.

--

Tim Roberts, [e-mail]

Providenza & Boekelheide, Inc.

 

---

Tim Roberts, VC++ MVP Providenza & Boekelheide, Inc.

Answer 6

hii

    i also want to develop USB webcam AVStream minidriver.,,

 i m using avshws avstream sample....

how to start , how to integrate webcam in avshws sample dont know ??? pls help what i do ?

Answer 7

hii Bigstone10

 can u help me for writing usb webcam ???

pls give valuable input to me regarding webcam...

how to start using avshws sample ???