Is there generation loss in HDV format??

[392]

Group, if I render out a scene, then plug that file back into my project to use it again, in the Sony HDV format will there be any generation loss? I cant seem to notice but then again my eyes don't work so well any more.

I have a very long project and am considering rendering all of the scenes, re-assembling the completed scenes and rendering out the final product. i had heard with the HDV mpeg2 format there was generation loss for multiple renders. Any comments are appreciated, especially from the pros!

Thanks all, 392

[johns0]

There's generation loss in any type of video re-rendering(re-encoding)and the more times you do it on the same video will start to introduce artifacts and grain etc...

[poisondeathray]

You don't mention the software but you say "Sony HDV" - I'll assume you mean Vegas Pro

Vegas Pro can smart render HDV - so on cuts only projects it will allow pass through of segments = no generation loss. It has to be setup properly, and vegas will tell you if it's smart rendering and say "no recompression required"

If you do transitions, effects, overlays etc. those sections have to be rendered (generation loss) , but the other sections can be passed through (no generation loss). Filters like Color correction and levels will affect everything so the entire thing will need to be re-rendered

[aedipuss]

depends on the editor you are using. sony vegas pro 9 can smart render HDV, which will not incur any loss except for the gops that contain cuts, edits, effects, transitions, etc. of course. the latest edius editor can also. not sure about pp cs5...

[edit] getting slow on the post button... pdr wins!

[edDV]

Like all MPeg video, if you decode it there is generation loss. Some editors only recode on changed GOPs, most recode the whole timeline.

DV editors work with frames, not GOPs. Only changed frames are recoded.

The amount of recode loss depends on bit rate. 25 Mb/s DV has low recode loss but is 720x480 SD. XDCAM-EX at 1440x1080 35 Mb/s has relatively low generation loss. HDV at 25Mb/s suffers more generation loss.

To put into perspective, HDCAM-SR RGB used for 2k film transfers uses 880 Mb/s at acquisition and is fully uncompressed to 3Gb/s for editing.

[392]

OK, all of this helps.... I am using sony vegas and pinnacle 14 (because of the magic bullet plugin), depends on the scene.. Cameras are Z5 and Z7 sonys. I cant seem to notice any significant loss with only one re-render but I wont take it beyond that.

On these movies that are shot in HD, are the pros making one giant timeline for the entire length or do they edit out each individual scene and re-build with the finished scenes?

Thanks for the responses!!

[edDV]

On these movies that are shot in HD, are the pros making one giant timeline for the entire length or do they edit out each individual scene and re-build with the finished scenes?

In Vegas Pro HDV project template you can render all at once, render nested timelines, or work in timeline segments then losslessly append the segments when done.

[392]

Thanks Ed, do you know where one can purchase some good instructional material on Vegas Pro. I am still learning the basics as it is a lot different from adobe, where my base is. What you just said is exactly what I need to learn how to do!

[edDV]

This is a good master Vegas link site.
http://www.blue7media.com/vegas/

YouTube has many mini-tutorials.