Getting information form audio devices

[ldarrambide]

Perfect, but some question to understand, and do better by myself later.

1. Tried to findout that, but missed it, know will know

DEFINE_DEVPROPKEY(DEVPKEY_Device_FriendlyName, 0xa45c254e, 0xdf1c, 0x4efd, 0x80, 0x20, 0x67, 0xd1, 0x46, 0xa8, 0x50, 0xe0, 14);
PROPERTYKEY pk.pid=14; memcpy &pk.fmtid uuidof("{a45c254e-df1c-4efd-8020-67d146a850e0}") sizeof(GUID)

2.
IMMDeviceEnumerator pEnumerator
IMMDeviceCollection pCollection

Why use create with pEnumerator and not with pCollection????

3. in MSDN,

pEndpoint.GetId waitsq for LPWSTR *ppstrId
Here, word*, why?

4. why this?

str s1.ansi(varName.pwszVal) s2.ansi(pwszID)
CoTaskMemFree(pwszID); pwszID=0; PropVariantClear &varName; pProps=0; pEndpoint=0

from MSDN example, there are no such variable casts, is it QM handling that impose such tricky ways?