HDV and Compression, editing mpeg 2 files.

1. BTS
   Member

   

    Hi All,

   I just completed my conversion from SD to HD, and I have a few questions about editing and re-editing HDV2 files.

   I run Pinnacle Studio 11, 14 and edit footage from a Sony HC5 MiniDV camcorder. In SD, I would import as AVI files and edit and then save to AVI files and author my discs in DVDit Pro. DVDit Pro would then conver the finished AVI files to mpeg, and I found that editing as mpeg files gave me quality problems with lots of bitmapping.

   Now I have DVDit Pro HD and a Blu ray burner, and with HDV, I can only capture as mpeg files (.mv2 or whatever they are called), which is a compressed format. My question is, if I edit and then save the files as mpeg HD files (1440x1080 HDV2 compatible, since that's what the camera is), will I lose quality when I then burn to Blu ray in DVDit Pro? What if I go in and re-edit my already edited and saved mpeg files? Do I lose quality because I am re-compressing the file? Does it make sense to save the files as 1080p mpeg files? Is there another format I should use? Do the file sizes vary depending on which mpeg format and size I use?

   I used to have a good hold on all of this with SD, but I'm a little behind on the HD formats, and I can't seem to find a simple, easy to understand breakdown anywhere... Any help is greatly appreciated!

   Thanks,

   -BTS

   Posted 2 years ago #

2. brainz2009r
   Member

   

   Hi,

   I'll give you a generic answer which will hopefully help with your general understanding of HDV for editing purposes.

   HDV is an mpeg format, which means it is compressed and any recompression into another format is going to involve some quality loss, unless downgrading resolution wise.

   HDV compression uses long GOP to keep file sizes down, in other words it stretches picture data a long way between frames to reduce the need for new unique picture data to be involved for every frame. Re-used data = reduced new data = lower file sizes. This is why an HDV file can be 8GB but when converted to an intermediate format for better quality editing it becomes 30GB. Intermediate file formats work by analysing the long GOP data and translating it into more choppable short GOP data. In other words you can now make an edit cut without the risk of losing important picture data some frames away.

   In summary. If you want to edit an HDV file, first convert it to an intermidiate format, edit and render it as an intermediate format and, if happy with the result, then reconvert to an HDV format for output back to camera.

   Hope that helps - any questions please ask.

   Richard

   http://www.youflash.co.uk

   Posted 2 years ago #

3. BTS
   Member

   

    Thanks Richard, that is helpful. Which intermediate format would you recommend?

   Posted 2 years ago #

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