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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Technogy for Recording Digital Audio

Instructors and students have been asking for the equipment to let them record and edit audio digitally for years at Malaspina. Students need to conduct interviews, create radio ads and create audio clips for class assignments. Faculty have long wanted simple ways to record, edit and upload their lectures in digital audio format for their students. Currently we have a very simplistic system in our digital video editing suites for working on editing digital audio. In the new library we will have specialised hardware and software for creating digital audio files that is more robust but we don't have a way of recording the files digitally, especially remotely. We have digital video cameras for recording video but we only have analogue audio cassettes for field recording audio. The quality is poor and the conversion to digital for editing is near impossible with our system. To streamline the process of audio production I am hoping to buy a couple of portable digital audio recorders. My requirements are affordability, ruggedness, size, ease of use, versatility, Macintosh compatibility, quality and maturity of the technology.

Hard Drive solutions provide the most storage space but are generally physically larger than other digital audio recorders and because of the power needed for the drive they tend to have worse battery performance. At the highest quality uncompressed mono recording you will be able to fit 1800 minutes (30 hours) onto one 10 GB non-removable hard drive. In standard 128 kbps mono MP3 format you will be able to fit over 10000 minutes (170 hours) onto one 10 GB non-removable hard drive:
Sound Devices 722 (40 GB) $2800
Edirol R-4 (40 GB) $1700
Fostex FR2 (4 GB) $1500
Sony PCM-D1 (4GB) $2000

Solid State audio recorders are small (average 750 grams), have great battery lives (average 7 hours of record time) and are easy to connect to a computer (USB and removable media.) The media (cf cards) are small and extremely rugged but cost are becoming more affordable (currently 1 GB costs $50.) At the highest quality uncompressed mono recording you will be able to fit 180 minutes (2 hours) on one 1 GB CF card. In standard 128 kbps mono MP3 format you will be able to fit over 1000 minutes (17 hours) onto on 1 GB CF card:
Marantz PMD670 $800
Marantz PDM660 $500
Denon F20R$1500
M-Audio MicroTrack $400

CD Recorders have the cheapest blank media but are also the largest digital audio recorders and have shorter battery life than other formats. Most of them only record in PCM uncompressed audio but are easily played in your computer or CD plyer and therefore are very versatile. Unfortunately because they only record uncompressed audio in stereo your maximum record time is 80 minutes per $1 (700 MB) disk:
Marantz CDR300 $800

Minidisk is a proven technology with a small form factor, good battery life and cheap and rugged media but their reliance on Sony's proprietary ATRAC audio CODEC and their Windows only connection software makes them less versitiale than other options. A standard $4 minidisk holds 80 minutes in stereo and 160 minutes in mono, the $5 Hi-MD (1GB) minidisk holds 475 minutes in ATRAC3plus and 94 minutes uncrompressed PCM:
HHB MDP500 $1500
Marantz PMD650 $1000
Sony MZ-RH1 $400 (Hi-MD now with USB 2.0 and Mac OS support)

DAT: is a favourite of the audio professional but it's linear nature and the fact that it still uses magnetic tape lessens it's appeal. Most models are discontinued with short battery lives (average 2 hours) and the tapes are difficult to find. The average $10 DAT tape records 120 minutes of uncompressed stereo digital audio:
Tascam DA-P1 $2800

If our department had unlimited resources I would recommend buying the Sound Devices 722 40 GB Hard Drive audio recorder. Although the device is very large it provides amazing quality, quick uploads, rugged construction and an unparalleled amount of recording space (over 120 hours at the highest quality!) But the cost is just too high. The much smaller and affordable Marantz PMD670 ($800) seems to best suit our needs. It is well constructed, provides flexible recording settings, small rugged media, fast convenient connection to computers and high quality sound. Hopefully the cost of CF cards will continue to drop making larger disks with longer record times available to students and employees. I will continue to research and would be happy to hear your thoughts and suggestions.

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Rack Mounting Video Editing Equipment

We are planning on rack mounting all of our video editing equipment in our 3 or 4 new video editing suites this Spring. I like the security, cooling and professional look of rack mounted equipment. Most of the equipment we are going to be using is rack-mountable but the actual computer is the biggest issue.

I could buy a rack-mountable Apple Xserve but it doesn't come with a graphics card or a SuperDrive or Digital Audio Toslink ports. You can add a PCI graphics card as a built-to-order option but not AGP and you need a AGP graphics card for Final Cut Pro. Apple's recently introduced Mac Mini has a small form factor and an enticing price that make it a possibility for using with in new video editing suites. They could be rack mounted but they lack gigabit ethernet and expandabillity. If we go with an Apple PowerMac G5 it has everything we need for a video editing station but it is not rack-mountable.

I have found Marathon Computer's interesting solution to rack mounting the G5 horizontally that may work. This solution fixes the problem of the PowerMac's height of 20.1 inches (rack width is only 19 inches) by chopping off it's handles with a hacksaw! I have some unanswered questions about the G5 and horizontal mounting. Will the SuperDrive (DVD Burner) work on it's side and is cooling effected by the orientation of the computers chassis? Another solution is to mount the PowerMac vertically with the Marathon G5 Rackmount and use the extra space with the with a G5 Sidekick or I could use Redco Audio's solution.

I liked the idea of rack mounting all the components including the NTSC monitor but have found that having it rack mounted makes it difficult to view while seated. Therefore in the new suites we will get furniture that accommodates both a computer and NTSC monitor.

September 2004

September 2005?

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