Sidebar 5 to 'Apple QuickTime 3.0 and the Avid/Microsoft Advanced Authoring Format ' Article
Why Motion-JPEG Is History

If you are shooting DV (or DVCPRO or DVCAM), do not redigitize from your S-video output (which returns you to analog) in Motion-JPEG. To get the same quality as DV, you need a much higher data rate, which will cost you more in hard drives. You will hear the argument that you should batch digitize at high compression (low data) rates, then 'batch redigitize' later. But with hard drive prices plummeting this extra step is increasingly more time and trouble than it is worth, and it degrades your picture.

Don't even consider a new range of products that says they will take in your DV as digital, and then transcode to M-JPEG for editing. While better than redigitizing, transcoding also will degrade your picture even at maximum data rates. Once it's in your computer as DV, edit it as DV.

The nonlinear editing companies are only telling you that Motion-JPEG works because they still have significant numbers of systems in their pipeline. When their stock is exhausted (sold to those of you who don't follow this advice) they will then advertise the advantages of DV or MPEG to get their customers to buy new and better systems.

The Defense Department has declared M-JPEG a legacy format, and has moved all critical media to I-frame MPEG2. The EBU/SMPTE taskforce has announced it will not support standardization of M-JPEG alongside DV and MPEG2. Standardization would require interoperability, and considering the very large number of proprietary M-JPEG codecs, the task force thought it unlikely that they could be made interoperable in the next few years (this despite QuickTime^Rs limited interoperability of M-JPEG). Even DV and MPEG streams have quirks designed in by some companies to prevent interoperability for marketing reasons. Sony's DVCAM, with its 'locked' audio, will not play correctly in their consumer DV players with 'unlocked' audio. Fortunately, nonlinear editing applications like Radius EditDV can ignore the metadata bits that are preventing interchange, so you can mix DV and DVCAM in a single project. And Panasonic has designed a non-standard and physically incompatible 'medium-size' DVCPRO cassette that will not play in Sony DV equipment. Once captured over FireWire into a nonlinear editor, you should be able to intercut DVCPRO and DVCAM.

Whichever DV version you use, make sure that your next editing system keeps your DV in its original form from end to end. Transfer your master back out to DV tape, make a safe copy clone, then make your Betacam SP or VHS copies from the master.

The following message should be required on all M-JPEG editing product advertisements - Warning. This Digital Video Guru (fill in favorite authority here) has found that Motion-JPEG degrades the image quality of your DV originals. It is a legacy format, destined to be obsoleted soon by DV and MPEG2.

Posted: May 1998
Bob Lamm, SMPTE/New England Newsletter/Web Page Editor
blamm@cync.com