[wdmaudiodev] Re: KSPROPERTY_JACK_DESCRIPTION
- From: "Daniel E. Germann" <deg@xxxxxxxx>
- To: <wdmaudiodev@xxxxxxxxxxxxx>
- Date: Mon, 19 Mar 2007 20:01:00 -0500
Hi, Mitch.
Thanks for this example. It helped a lot!
I have two follow-up questions I hope you can answer.
1. The docs for KSMULTIPLE_ITEM say:
Size
Specifies the size in bytes of this header and the property data
that follows.
Count
Specifies the number of buffers that follow this header.
In your example, ->Size appears to be the size of each item being returned
(sizeof(KSJACK_DESCRIPTION)). The "videocap\usbintel" sample (prpget.c),
which also uses KSMULTIPLE_ITEM, sets ->Size to the total size of all items
being returned, excluding the KSMULTIPLE_ITEM header (Count * sizeof(item)).
I'm doing what your example did, and it works. But I thought I'd better
double-check to make sure I don't get a surprise in the future, since the
examples and docs don't seem to match. Is what you did in your example the
correct usage when returning KSJACK_DESCRIPTION information?
2. The docs for KSJACK_DESCRIPTION indicate that the ChannelMapping field is
one of the enumeration values from EChannelMapping. But it sure seems to
act more like a straight channel bitmap (bit 0 = left, bit 1 = right, bit 2
= center, etc.; similar to other audio APIs (e.g., SPEAKER_FRONT_LEFT,
SPEAKER_FRONT_RIGHT, etc.)) and 0 means "undefined / unknown"
(KSAUDIO_SPEAKER_DIRECTOUT). That kind of makes sense, since ChannelMapping
is defined as a DWORD, and all the other fields that are enumeration values
are defined as the enum's typedef.
For example, when I set ChannelMapping to 5 (ePcxChanMap_Unknown), my jack
info shows up as "L C". That doesn't match "unknown", but it does make
sense for a location bitmap of 5 (Left + Center). And when I set it to 0
(ePcxChanMap_FL_FR), my jack info is blank. Again, that doesn't match the
"FL/FR" location specified by the enum, but it is what I'd expect for a
location bitmap of 0 (undefined or unknown location).
Is what I'm seeing correct? Or is it supposed to really be an
EChannelMapping enumeration value?
Thanks very much!
-Dan
-----Original Message-----
From: Mitchell Rundle
Date: Mon, 12 Mar 2007 12:09:59 -0700
Subject: [wdmaudiodev] Re: Fwd: Re: KSPROPERTY_JACK_DESCRIPTION
Nikolay, sorry for the delay.
Starting with the MSVAD "simple" sample in the WDK, here's what it takes to
add support for KSPROPERTY_JACK_DESCRIPTION.
<portion of original email deleted for clarity>
3) In MinTopo.cpp, implement the property handler:
NTSTATUS
CMiniportTopology::PropertyHandlerJackDescription
(
IN PPCPROPERTY_REQUEST PropertyRequest
)
{
PAGED_CODE();
ASSERT(PropertyRequest);
DPF_ENTER(("[PropertyHandlerJackDescription]"));
NTSTATUS ntStatus = STATUS_INVALID_DEVICE_REQUEST;
ULONG nPinId = (ULONG)-1;
if (PropertyRequest->InstanceSize >= sizeof(ULONG))
{
nPinId = *(PULONG(PropertyRequest->Instance));
if ((nPinId < ARRAYSIZE(JackDescriptions)) &&
(JackDescriptions[nPinId] != NULL))
{
if (PropertyRequest->Verb & KSPROPERTY_TYPE_BASICSUPPORT)
{
ntStatus =
PropertyHandler_BasicSupport
(
PropertyRequest,
KSPROPERTY_TYPE_BASICSUPPORT | KSPROPERTY_TYPE_GET,
VT_ILLEGAL
);
}
else
{
ULONG cJacks = <number of jacks associated with this pin
(nPinId) >
ULONG cbNeeded = sizeof(KSMULTIPLE_ITEM) +
sizeof(KSJACK_DESCRIPTION) * cJacks;
if (PropertyRequest->ValueSize == 0)
{
PropertyRequest->ValueSize = cbNeeded;
ntStatus = STATUS_BUFFER_OVERFLOW;
}
else if (PropertyRequest->ValueSize < cbNeeded)
{
ntStatus = STATUS_BUFFER_TOO_SMALL;
}
else
{
if (PropertyRequest->Verb & KSPROPERTY_TYPE_GET)
{
PKSMULTIPLE_ITEM pMI =
(PKSMULTIPLE_ITEM)PropertyRequest->Value;
PKSJACK_DESCRIPTION pDesc =
(PKSJACK_DESCRIPTION)(pMI+1);
pMI->Size = sizeof(KSJACK_DESCRIPTION);
pMI->Count = cJacks;
// TODO: copy jack info struct(s) into pDesc...
ntStatus = STATUS_SUCCESS;
}
}
}
}
}
return ntStatus;
}
<portion of original email deleted for clarity>
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