DV Generational Loss in Avid

There has been some disagreement about the potential for generation loss in DV video via Firewire in Avid. The idea is that DV video, as data, is transferred and ‘captured’ as a simple data stream via a Firewire connection - there should be no loss, as it is simply moving data back and forth.

But is that the case?

I created an image in Photoshop of a variety of test patterns, imported it into Avid as 1:1 media, then output from Avid to a DVCAM tape. Then I proceeded to capture from the tape, put the captured footage back on the tape, and capture off again.

With these clips I then exported, from Avid, single TIFF frames from each clip and compared those frames in two ways:
In Photoshop - Placing Generation 1 (the first capture from the tape) on Layer 1, I then stacked up each of the other generations above it, set their transfer mode to ‘Difference’ and applied an Adjustment Layer with Levels set with 1-24 (to highlight any differences).
With a Checksum - Using WinMD5Free I got the MD5 checksum value of each frame.

My conclusion? There’s no difference. No generational loss is introduced with DV25 capture from a DV source via Firewire into Avid and subsequent layback via Firewire to DV.

However it is important to note, that any changes to the picture will introduce variations. In Avid, it is best to ensure that all new media (Titles, Effects, Imported graphics) is at a higher quality than DV25 (Ideally 1:1 or alternatively DV50).

I won’t post any picture, they are boring, and all the same, however the checksum details are below:

Generation 1 (first capture from Tape):
4128ef910dbe661d4238574ed3b3fbe7

Generation 2 (Gen 1, put on tape, then captured again):
4128ef910dbe661d4238574ed3b3fbe7

Generation 3 (Gen 2, put on tape, then captured again):
4128ef910dbe661d4238574ed3b3fbe7

Generation 4 (Gen 3, put on tape then captured again):
4128ef910dbe661d4238574ed3b3fbe7