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8.5 Recording Digital
Unlike analog soundcards which produce empty wave files (or noise) when no input signal is
present, digital I/O cards always need a valid input signal to start recording.
To take this into account, RME has included three unique features in the Hammerfall DSP
system: a comprehensive I/O signal status display (showing sample frequency, lock and sync
status) in the Settings dialog, status LEDs for each input, and the protective Check Input
function.
If a 48 kHz signal is fed to the input and the application is set to 44.1 kHz, Check Input stops
the system from recording. This prevents faulty takes, which often go unnoticed until later on in
the production. Such tracks appear to have the wrong playback rate - the audio quality as such
is not affected.
The sample frequency shown in the Settings dialog (see chapter 9, screenshot Settings) is
useful as a quick display of the current configuration (the board itself and all connected external
equipment). If no sample frequency is recognized, it will read 'No Lock'.
With this configuring any suitable audio application for digital recording is simple. After
selecting the required input, Hammerfall DSP displays the current sample frequency. This
parameter can then be changed in the application's audio attributes (or similar) dialogue.
The screenshot to the right shows a typical dialog
used for changing basic parameters such as
sample frequency and resolution in an audio
application.
Any bit resolution can be selected, providing it is
supported by both the audio hardware and the
software. Even if the input signal is 24 bit, the
application can still be set to record at 16-bit
resolution. The lower 8 bits (and therefore any
signals about 96dB below maximum level) are
lost entirely. On the other hand, there is nothing
to gain from recording a 16-bit signal at 24-bit
resolution - this would only waste precious space
on the hard disk.
It often makes sense to monitor the input signal or send it directly to the output. This can be
done at zero latency using TotalMix (see chapter 15).
TotalMix also includes a useful automatic real-time monitor function, see chapter 15.8 for
details. Activating record in the application causes the input signal to be routed according to the
current mixer settings.
Currently two solutions exist which enable an automated control of real-time monitoring. ZLM
(Zero Latency Monitoring) allows monitoring in Punch I/O mode - with this the system behaves
like a tape machine. This method has been implemented in all versions of Samplitude (by
SEK'D), and can be activated using the global track option 'Hardware monitoring during Punch'.
The other solution is Steinberg's ASIO protocol with our ASIO 2.0 drivers and all ASIO 2.0
compatible programs. When 'ASIO Direct Monitoring' has been switched on the input signal is
routed in real-time to the output whenever Record is started.
User's Guide HDSP System Multiface © RME
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