Recording | Alesis Hammerfall DSP System instruction

12.5 Recording

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 two unique features in the HDSP MADI: a compre- hensive I/O signal status display (showing sample frequency, lock and sync status) in the Set- tings dialog, and the protective Safe Mode / Frequency function.

If a 48 kHz signal is fed to the input and the application is set to 44.1 kHz, Safe Mode / Fre- quency 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 11, screenshot Settings) is useful as a quick display of the current configuration (the box itself and all connected external equipment). If no sample frequency is recognized, it will read ‘No Lock’.

This way, configuring any suitable audio application for digital recording is simple. After select- ing the required input, HDSP MADI displays the current sample frequency. This parameter can then be changed in the application’s audio attributes (or similar) dialog.

The screenshot to the right shows a typical dialog used for changing basic parameters such as sample frequency and resolution in an audio ap- plication.

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 reso- lution. The lower 8 bits (and therefore any signals about 96dB below maximum level) are lost en- tirely. 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 24).

Currently two solutions exist which enable an automated control of real-time monitoring. ZLM 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 Magix), and can be activated using the global track option 'Hardware monitoring during Punch'. As ZLM is limited to MME, this mode is no longer supported since TotalMix version 2.3.

The second solution is Steinberg’s ASIO protocol with our ASIO 2.0 drivers and all ASIO 2.0 compatible programs (even Samplitude…). When 'ASIO Direct Monitoring' has been switched on, the input signal is routed in real-time to the output whenever a recording is started.