RME Audio Hammerfall Digiface, User Manual

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User's Guide HDSP System Digiface
© RME
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12. Operation and Usage
12.1 Playback
The HDSP system can play back audio data only in supported modes (channels, PCM) and
formats (sample rate, bit resolution). Otherwise an error message appears (for example at 22
kHz and 8 bit).
In the audio application being used, HDSP must be selected as output device. This can often
be found in the
Options, Preferences or Settings menus under Playback Device, Audio Devices,
Audio etc.
We strongly recommend switching off all system sounds (via >
Control Panel /Sounds <). Also
HDSP should not be the Preferred Device for playback, as this could cause loss of synchroniza-
tion and unwanted noises. If you feel you cannot do without system sounds, you should con-
sider buying a cheap Blaster clone and select this as
Preferred Device in > Control Panel
/Multimedia /Audio <.
The screenshot shows a
typical configuration dialog
of a (stereo) wave editor.
After selecting a device,
audio data is sent to either
an ADAT or SPDIF port,
depending on which has
been selected as playback
device.
Increasing the number
and/or size of audio buff-
ers may prevent the audio
signal from breaking up,
but also increases latency
i.e. output is delayed. For
synchronized playback of
audio and MIDI (or simi-
lar), be sure to activate the
checkbox ‘Get position from audio driver’.
The HDSP system’s ADAT optical interface allows sample rates of up to 96 kHz using a stan-
dard ADAT recorder. Single-channel data at this frequency requires two ADAT channels,
achieved using the
Sample Multiplexing technique. This reduces the number of available ADAT
channels from 8 to 4 per ADAT port. Under Windows MME, channels are routed to ADAT de-
vices in double-speed mode as follows:
•
Only stereo pairs (1+2) and (3+4) of the ADAT port are available
This kind of implementation allows a problem-free usage of the ADAT port in both Single and
Double Speed, as the routing doesn't change. However, the hardware spreads the data differ-
ently: Channel 1 is transmitted via channels 1 and 2, channel 2 via 3 and 4 etc.
Please refer to the diagram in chapter 18.2. Routing for record and playback is identical.