Recording digitally

                        with the Zaxcom DEVA

 

                          By David Lewis Yewdall M.P.S.E.

 

Extract from Chapter 5 of  “The Practical Art of Motion Picture Sound”

          copyright 1997-&-2003  Focal Press

 

 

 

Recording Straight to Hard Disk

     The Zaxcom Deva II, a direct-to-disk digital audio recorder. The production sound mixer brings a highly durable unit into any recording scenario without the sensitivity factor of traditional computer disk recording systems.  The Deva II can record up to four dedicated channels of 48kHz information.

 

                             

 

                              Don't judge the Deva by its size. This little package carries a                                       

                         tremendous amount of direct-to-disk recording firepower.

                         Using a keyboard, (out of view) screen unit on the shelf above allows

                         the Mixer to enter all kinds of important data into the audio file                              

                         directory.    

                                                                      (Photo by David Yewdall)

 

     The high-quality 24-bit analog-to-digital converters on both the microphone and line inputs ensure a wide dynamic range. The AES interface can make transparent transfers of 24-bit material from other digital sources. The Deva can record either a Sound Designer II audio file or either mono- or polyphonic Broadcast Wave audio files. By utilizing a small keyboard, shown in Figure 5.7, the production Mixer enters pertinent data into the audio file directory.

     The Deva uses a 40-gigabyte removable internal hard drives. Zaxcom claims these hermetically sealed drives can withstand as high as 100 "Gs" -- certainly twenty times more than I intend ever to endure -- but it does bring a lot of recording time for the Mixer on the set. A separate DVD-RAM unit is easily hooked up so that the Mixer can lay back protection copies to a recordable DVD, using the hard drives as a working medium only to record and file-manage. Once the DVD is made and the material is safe in the hands of the post-production transfer facility, the Mixer can wipe the drive clean and use it again, or put in the archive for safe keeping as a back-up protection for all the dailies.

 

                                  

 

                             The Deva / Cameo array.    

                                                                      (Photo by David Yewdall)

 

     The Mixer may choose to put the Deva into an "Intermittent" mode, which allows the unit to automatically make back-up recordings to the DVD when the Deva is not in "Record" mode. As soon as the "Record" mode is off, the Deva automatically continues recording back-up audio files to the DVD-RAM over the SCSI connector. If the Mixer wants to record both to the Deva hard drive as well as to the DVD simultaneously, he or she switches the Deva to "Turbo" mode.

     The unit always maintains a ten-second "pre-roll" in the RAM buffer, so if the Mixer presses the "Record" button, the previous ten seconds is automatically laid down to the hard drive, thereby doing away with waiting for the pre-roll. This feature is extremely helpful on a busy shoot, where the Mixer must review previous recordings or where the director either does not understand pre-roll protocol or has not thought to warn sound that he or she is about to go for a "take" and roll cameras.

     Rather than being caught right in the middle of playing back a previous cue and finding yourself totally incapable of spinning down to virgin tape to start recording again, simply hit the "Record" button, which automatically starts recording to the hard disk. You will not damage or record over the material you are reviewing, as it is impossible to accidentally record over a section of the hard disk that has already been used. Remember, computers do not work in a linear fashion. You can change from single-channel recording to multiple channels for the next recording set-up by simply touching the proper buttons to tell the Deva how you want to record. In addition to industry standard XLR connectors, the Deva has a break-out cable with a multi-pin connector for line inputs.

 

                                     

 

     Note that the flat screen display for the Zaxcom Cameo mixer clearly shows the four audio channels, here running line-up tones.  Using a keyboard, (not shown) off to the side of the unit, the recording mixer quickly enters the scene, angle and take data (that show up in the "slate" icon in the upper right hand corner.  This entry along with the timecode is embedded in the directory of the audio file itself, thereby streamlining and removing possible errors by the assistant picture editor later in assimilating the material into the non-linear editing system being used.

     Several other companies are actively engaged in perfecting direct-to-hard-drive recording systems for the field. The ability to mirror duplicate back-up drives quickly to cost-effective medium as well as the ability to build in data files to the directory of each audio file as they are created greatly enhances not only speed issues but also defeats the chances of error in data assignments later at the laboratory or at picture editorial.