Updated: I’ve done a little research on image evaluation, and decided that SSIM presents the best option to evaluate the the perceptual quality. SSIM results are now included below.

In a recent thread on the Avid Community Forums there was some discussion of the quality of Avid’s downconversion from HD to SD. I have used various downconvert methods from within Media Composer in the past and have never had any serious problems with any of the results, but I figured I might be able to conduct some vaguely reasonable tests. Read the rest of this entry »

NOTE: Since this article was written Avid has introduced AMA into Media Composer (from version 3.5) which greatly simplifies the workflow with EX material. From Media Composer 3.5 onward working with XDCAM (SD, HD and EX) and P2 in Avid is incredibly simple and immediate.

I’m a fan of XDCAM EX. I like the format and think it offers great quality given it’s bitrate and cost. The cameras are good the SxS media is pretty decent. I have my general reservations and concerns about Solid-State recording, but assuming you have a reasonable process for managing backups you should be fine.

When EX first came out there was no EX support. It was added in Media Composer 3.0.5 I believe. Shortly after that happened Sony released version 2 of their Clip Browser software which had a ‘Avid AAF’ export function that made it a lot easier to get EX footage into Media Composer. Avid even posted a tutorial about the process.

Essentially this feature unwraps the MP4 XDCAM EX files and re-wraps them as MXF Op-Atom (Avid’s mediafile container) and places those files directly into one of Avid’s media directories (such as F:\Avid MediaFiles\MXF\2) and then creates an AAF file that contains a clip describing that shot (basically the easiest way to get the shots into a bin). This process is simple and reasonably quick and works fine… Or so I thought.

What is lacking in this process in Metadata control. When Clip Browser generates the MXF files it’s creating files that lack some of the metadata that Avid would normally use to relink a clip to media. Most obviously there is no Source or Disc Label associated with any of these clips. What this means is that Avid cannot relink this media. So if the Avid MXF file you create from Clip Browser is lost at all it cannot be relinked. Even going back to Clip Browser and re-exporting the same clip or clips to the same media directory will not create media that Avid will reassociate with existing clips or sequences.

Basically if you import clips this way you are absolutely locked in to those specific media files. No backup short of storing the actual files as they are created in the Avid MediaFiles directory will allow a recovery or relink.

The easiest way to avoid this problem is actually to use the older process. Using Clip Browsers ‘MXF for NLE’ export setting. This will create OP-1A MXF files that you can then import into Media Composer (the Avid will rewrap them as OP-Atom and relocate them to it’s media directory). It is a slower process, but as it’s a standard import process all the necessary Metadata will be stored with the clips to allow a Batch Import later.

Ideally this will soon not be necessary if Avid incorporates EX import directly into Media Composer, cutting out the Clip Browser middle-man.