Skip to main content
csgaraglino
csgaraglino
Known Participant
August 9, 2011
Question

Down-Converting 1080p to 720p

  • August 9, 2011
  • 2 replies
  • 33406 views

I shoot AVCHD 1080p form a verity of different cameras - but 99% of all my final projects are for the Web or DVD - no big screen and no blue-ray. I want to shoot what I can in 1080p for future use or projects.  My question is what is the best solution (free or nominal fee) for down-converting my footage to 720p for storage and editing?

    This topic has been closed for replies.

    2 replies

    B
    billmatthiesen
    Participant
    August 10, 2011

    Can I ask a related question here? (maybe in the "dumb question department) ...

    I'm also shooting with a brand new NX5U -- which lets me shoot 1080 and 720 simultaneously (one to chip, the other to a flash drive). My projects also end up on the web and non-blueray DVDs.

    So is the quality going to be better if I work in 1080 timelines and then import the final into a 720 timeline? Or is it going to look the same if I work in 720 right from the start?

    I haven't run any tests to judge rendering time, etc. I'm assuming higher rez means longer processing time. But maybe it's worth it for better quality.

    Anyone have any advice about this?

    Thanks in advance!

    D
    Dave Merchant
    Legend
    August 12, 2011

    It really depends on what you're doing to the footage, and what hardware it comes from. 1080>720 isn't an integer step so there will be pixel-blending on the resize, and with most prosumer kit having chroma subsampling you're not reading complete per-pixel data in the first place.

    Even rendering to AVI I doubt anyone could look at an unedited 720p clip on a TV or Web video and tell if it came from a 720p capture or a scaled 1080p capture - in the former you'll have lens blur and chroma SS across pixels, in the latter you'll have fractional resampling giving near-enough the same feel, but if you apply effects that work on a per-pixel basis (such as unsharp masks or keying) to the footage before scaling they can look different. Not necessarily better or worse, just different; and your audience will only see one version so what you notice doesn't really matter!

    It certainly makes sense to grab the biggest frames you can on location, as aside from any future use in full-HD projects you get the option to place it at larger than "fit" size, so you have leeway to crop stuff out or stabilise motion.

    Prior to Mercury and solid-state drives, working in 1080 over 720 was a really noticeable drag - but now it's more about the codec than the frame size. A "tricky" codec at 480 can be more laggy to scrub than a "simple" codec at 1080, it depends on how much work your CPU has to do extracting the frame data before the MPE can scamper off with it.

      I
      Ironbird Studios
      Participant
      September 18, 2011

      Brilliant response David Merchant.

      Can anyone offer advice on this related situation in Premiere Pro 5,5:

      I have footage from a 3 camera shoot.  One of the cameras was a locked off wide shot that I now prefer it be more zoomed in.  I don't mind having the project in 720 - it's primary destination would be You Tube / Vimeo & DVD.   All which would work well in 720 as far as I am concerned.

      The footage was shot at 1080/24. 

      Could I simply edit the project in a 720 timeline, and scale up the camera track that I prefer more zoomed in?  Does anyone know what the exact scale would be for 1080 to 720?  For some reason, when I use the source file in a 720 Premiere sequence, the clips automatically scale to the sequence size.  I'd want to scale it as best I could to retain a pixel to pixel relationship to avoid blur etc.  But David, you say that it wont scale pixel to pixel with effects.  The only effect I'd use on a scaled track would be color grading (with Red Giant Looks or Colorista II).  What is the best way to do this - if there is one? 

      Can I at least assume this method will look better than scaling up the particular camera in a 1080 sequence? 

      Thanks,

      Angelo

      Colin Brougham
      Colin Brougham
      Participating Frequently
      August 9, 2011

      Why downconvert? You can use 1080p footage in a 720p sequence, simply by scaling it down or using the Scale to Frame Size preference or command. It'll save tons of time and space.

      csgaraglino
      csgaraglinoAuthor
      Known Participant
      August 9, 2011

      Hmm... It is my impression that if I edit with actual 720p files, it will be less strain on the system both in editing and rendering as well has hard drive space? The hard drive is a given - I store the originals and only edit with copies - these copies being 720p would be roughly half that of the 1080p.

      E
      excited_Genie16B8
      Legend
      August 10, 2011

      The size of the copies depends on the bitrate used, frame size has little to no bearing on the matter.  In order to get half the size, you'd need half the bitrate.

      I'd agree with Colin on this one.  Don't worry about copies, use the originals.

      Terms & ConditionsAccessibility statement
      Using the community Terms of use Privacy Cookie preferences Do not sell or share my personal information ad choicesAdChoices