Microsoft has made extensive changes in the Vista/Windows Server 2008
audio interface in an effort to improve performance and to impose strict
Digital Rights Management (DRM). Unfortunately, the changes have proven
to be a catastrophe for users and vendors of audio converting hardware.
Windows XP/Server 2003 audio drivers do not work with Vista and the
implementation of Vista compatible drivers can be a complicated and time
consuming process. Even worse, depending on a specific implementation, a
driver may or not support the features that are required by individual
application programs.
A case in point is the capability of recording streaming data in real
time. Most Vista audio application programs require a digital Play Back
Device interface that comes under a variety of names including "Stereo
Mix", "What U Hear" and "Digital Audio Interface".
The application program will not be able to capture the audio unless one
of this interfaces is present. Its existence apparently depends on the
specific sound card device and the implementation of its driver. A
considerable amount has been written on this subject in various Internet
forums and Web sites. The user is unfortunately of out luck if his sound
card/driver combination doesn't support the required interface.
There are several ways to capture streaming audio data. The easiest is
to use a sound card/Vista driver combination that has a digital playback
interface as is described above.
Secondly, some cards have a software controllable audio loopback that
can provide similar capability. Examples are the LynxStudio L22 and the
RME HDSP 9632.
Finally, the analog output can be cable patched back to the analog input
of either the same sound card or a second card.
We have Audacity 1.3.3 beta running on Windows Server 2008 which shares
much code in common with Vista. Our RME HDSP 9632 sound card and its
driver do not support the "Playback Digital Interface" described above.
There is, however, a software controlled loopback function that works
perfectly with the Audacity beta. Audacity also works well with the L22
sound card which has similar loopback capability. We use the loopback
approach to capture streaming audio. The technical details are described
in more detail in the RME HDSP 9632 manual which is available on-line
at:
http://www.rme-audio.com/english/download/hdsp9632_e.pdf