Audio Swicher and Volume Control

One issue that I ran into in the new video editing suites is that I had no way to switch audio sources for the powered speakers that we purchased. If I connected them to the computer the video sound would be out of sync with the NTSC monitor and if I connected them to the VHS output you would not be able to hear audio from computer applications such as iTunes or the sound effects from iMovie. Also If I connected the speakers directly to the VHS there is no volume control and the line level out to the speakers is very loud.


My solution was to get a passive pre-amp (really a limiter) with 2 sets of stereo inputs, one set of stereo outputs a switch to be able to toggle between the 2 sources and a volume dial. Unfortunately all I could find was very expensive and complicated passive pre-amps (they are popular with audiophiles because the add no extra noise or distortion to the audio.)


Luckily for me I found this schematic online and I have a very handy coworker named Neal who was able to create one for me using the exact connections I needed (RCA stereo and TSR 3.5mm mini inputs and stereo XLR outputs)


The sound quality is excellent, it is easy to use and it looks great.

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Completed Video Editing Suites

After years of planning and months of work we have finished building 3 digital video editing suites. I say finished but there will always be room for improvement.




Not all the equipment is rack mounted yet (the G5 for instance, because the DVI cable is too short) and it could use some more signs and labels but I think it is way better than the system we had before.

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New Audio Editing Suite

Now that I've researched the necessary hardware for recording digital audio I can turn to studio hardware and software. Not having much experience with audio I turned to my good friend Kam Abbott (audio engineer for CIB Radio), he gave me advice for building the following system.

I started with software, which had to be easy to use and Mac compatible. My colleague Scott Watts (Media Specialist at BCIT) suggested the free cross platform audio editing software Audacity from sourceforge.net. Apple has two audio editing software packages GarageBand and Logic but both applications centre around music production instead of simple audio editing. For those that are a bit more flush there is the high-end DigiDesign ProTools LE Software and Digi 002 Rack. This solution is more powerful than the others and is rack-mountable but is very complex and costly. In the end we went with the open source choice, it seems relatively simple and is free.

The G5 PowerMac that we purchased for the suite has a line in, line out, headphone, optical (toslink) in and out ports but doesn't have any balance audio XLR microphone inputs. We are going to use two studio microphones with XLR connections so we needed to come up with a solution. The various external audio hardware products (using either Firewire or USB) would give us more inputs and outputs. But I like the idea of using a simple mixing board such as the Behringer Eurorack UB1202 which allows us to connect our various audio devices and control them before they go into the computer via a stereo TSR 3.5mm mini style cable.

We purchased two sets of microphones; one set for field recording (the robust dynamic mic: Shure sm58) and one set for the studio (the very good quality but remarkably affordable ribbon mic Studio Projects C1.) I was told a good microphone isn't enough for good voice recordings so we purchased two microphone voice processors (Symetrix 528E.)

For monitoring the sound we have 2 pairs Beyerdynamic DT 231 studio headphones (very affordable, nice sound quality and very robust) and a pair of Tannoy Reveal passive studio speakers powered by a Tascam PA-30 stereo amplifier.

The audio editing room is not totally sound proof so it limits it's capabilities as a recording studio but it should suffice for voice-overs and mock radio ads.

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Controlling Editing Stations remotely with Apple Remote Desktop

Sometimes I can't go to the video editing stations to troubleshoot problems that students are having. Often the students will come to me asking for assistance and I have trouble understanding the problem or I can't help them without going to the editing suite. I would like some software that allows me to view and control an OS X workstation.

One solution that I'm looking at is a 10 client copy of Apple Remote Desktop. This program is a more advanced version of VNC for Mac OS X. It allows an administrator to take control of a workstation remotely. I could use the software from my office or the Information Commons desk (were I spend every morning helping with general multi media problems) and control any one of the 3 video suites that would have the client software installed.

Features such as screen sharing, remote instalation and comprehensive reporting makes this software very usefull in instruction, especially in ellemtary schools.

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Playing DivX Movies in OS X

Poroject Omega, a great French OSX developers site, has a easy to follow how to PDF for playing and fixing compressed DivX video files on your Mac OS X computer.

For Creating DivX movies on Mac OS X you can use the $19.99 DivX Pro™ 5.2.1

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Video Editing Furniture

When furnishing something as complicated as a video editing suite functionality, ergonomics and room for growth are essential elements that must be considered.

Standard computer desks and workstations, available at most department stores, are based on typical computer components: monitor, keyboard, printer, mouse and perhaps a scanner. You will not likely need a printer or scanner with your editing setup, but it is likely you'll need room for two or three monitors, a set of speakers and a microphone. You will need room to hold scripts, videotapes and CDs. You may also have one or more VCRs and an audio mixer. Whatever your setup, you want to be able to reach all the controls comfortably.

Video editing equipment is often 19" rack-mountable and your furnishings should accommodate this. Rack mounted equipment is accessible, secure and uses space efficiently. You may decide to purchase a stand-alone rack enclosure to accommodate your equipment or rack bays build into your workstation desk may be sufficient.

An important requirement of our digital video editing suites is room for teamwork. Most video projects at Malaspina are worked on by a team of 2 or more students. The following is our current plan for the 3 video editing suites in the new library.

As you can see we're maximizing space by placing the desks in the corner of the rooms, this allows for a wide desk (250 cm wide) and for 3 people to sit comfortably. The rack-mounted equipment will be housed in a separate rack enclosure on casters that will be locked and attached to the wall. If service is needed the racks can be detached from the wall and swung out. The cables coming from the rack to the monitors and peripherals at the desk (and power and network connecting to the wall) will have to be long enough so that the rack can be swung away from the wall with out damage or disconnection.

Here are some companies that specialize in A/V furniture:
http://www.martinandziegler.com/
http://www.omnirax.com/site/
http://www.anthro.com/
http://www.winsted.com/multi.htm
http://www.biomorphdesk.com/

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Video Editing over Gigabit EthernetCentralized Digital Video Storage

Currently at Malaspina video projects are stored on the hard drives locally, if students or employees want to work at a different editing station they can't access their projects unless we move them manually using an external Firewire drive. Often the suite a project was started on will not be available when the group is. I hope to create a system of storing projects in a central location where it can be accessed from any of our suites.

To accomplish this we are planning on using an Apple Xserve running Mac OS X Server connected to the workstations running Mac OS X with 1 Gbps Gigabit Ethernet using a dedicated Gigabit switch. We could use 2 Gbps Fiber Channel for increased network speed but the cost of host bus adapters, cables, switches and specialized SAN software (such as Xsan and ImageSAN) is prohibitive compared to cost of Gigabit Ethernet (which comes standard in Apple Xserves, PowerMac G4s and G5s.) Accounts could be located on the Xserve and projects stored in the user's Movies directory.

This sort of setup should accommodate up to four SD video editing suites simultaneously or perhaps two HD video editing suites (which we have no current plans for but I will provide data for interest sake.) Gigabit Ethernet is rated at a maximum of 125 MBps, although in reality users may achieve only 60 MBps to 70 MBps due to network overhead. Standard Definition video compressed for DV is roughly 3.5 MBps. DV compressed HD video (DVCPRO HD) requires roughly 12.5 MBps of bandwidth for realtime playback. To provide enough bandwidth for editing you should multiply its bandwidth requirement by a minimum of 2 (7 MBps is the highest amount of bandwidth that one iMovie station could generate in my single workstation tests). Using that math SD video editors will require 28 MBps (3.5 * 2 * 4 workstations) and one HD video editor will require 25 MBps (12.5*2) which fits into our 60 MBps to 70 MBps achievable bandwidth with Gigabit Ethernet.

I believe the real issue will be internal bandwidth (sustained disk read/write) on the server. The G5 Xserve with a single SATA hard drive for video will only give us about 25 MBps sustainable read/write, way too slow for four simultaneous editing suites but should be able to handle two effectively. If we add a PCI Hardware RAID card and 2 more SATA hard drives it should increase performance to roughly 50 MBps sustainable read/write allowing up to five clients to edit video simultaneously.

Another issue is the Xserves currently have a maximum storage capacity of 750 GB, this sounds like tons of storrage but you never know how your needs will grow. Especially since there would be no redundancy to the data. That means if one of the 3 drives used in the 750 GB RAID were to have a problem all students in all the suites would loose all there projects. This is unexceptable. Capacity, performance and redundancy could be increased with the addition of one or more Apple Xserve Raids (up to 200 MBps read/write with a maximum storage capacity of 3500 GB per unit.) Steve Mullen has a great article on the Xserve Raid and it's real world performance at Video Systems Magazine.

I have connected the 4 workstations to the Gigabit switch which is connected to the Xserve's second Ethernet adapter. The Primary ethernet adapter is connected to the College's 10/100 mb LAN. I then set up Mac OS X Server to share it's network from the primary Ethernet to the secondary port. Later I will tackle the daunting task of setting up workstation authentication through the Xserve

I've had some experience setting up Mac OS X servers before but if I run into problems I know were I can find Help. Now if I can incorporate this system of server storage of projects with template accounts and Windows account login I will be a very happy video tech.

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