DV compression

[Bester]

Could someone please tell me what compression algorithms dv uses?

For I would like to know if quality of image improves if I letterbox with my camera or later with software.
Does the pic with the camera letterbox give better quality?

thx

[bb]

DV uses the DV compression algorithm :)

It is very similar to MJPEG, but there are some differences, too. Read the comparison between MJPEG and DV at Adam Wilt's site (to be found through the "Links" sticky thread).

What kind of camera do you have? There are different types of letterboxing, thus without further information I can't tell you whether there will be a quality improvement or not.

bb

[Bester]

Good link!

Sadly my cam is a cheap one with fake 16/9 mode, it simply letterboxes the image.
My thought was that the video is letterboxed first and then compressed inside the camera.
The black bars compress very good so there is more quality "left" for the real image.
If I would letterbox later in post, the whole pic is compressed first in the camera.

[theReal]

The black bars compress very good so there is more quality "left" for the real image. From my experience with black bars and MPEG compression, it's always best not to have black bars. The hard black edges, (if not exactly at the edge of an mpeg block) compress very badly so that you will lose compressibility most of the time!

However, DV is not MPEG - but DV uses DCT as well, so I guess it's similar