14 Replies Latest reply on Sep 18, 2011 3:35 PM by Ironbird Studios

    Down-Converting 1080p to 720p

    csgaraglino Newcomer

      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?

        • 1. Re: Down-Converting 1080p to 720p
          Colin Brougham Ninja

          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.

          • 2. Re: Down-Converting 1080p to 720p
            csgaraglino Newcomer

            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.

            • 3. Re: Down-Converting 1080p to 720p
              Jim_Simon Legend

              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.

              • 4. Re: Down-Converting 1080p to 720p
                billmatthiesen Newcomer

                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!

                • 5. Re: Down-Converting 1080p to 720p
                  John T Smith Legend

                  >worth it for better quality


                  In general, I will say always use the best quality possible for editing


                  I used to use a Sony 8mm analog camcorder, with a Pinnacle Dv500 card to digitize, finally going to a DVD... with "about" the same quality as a VHS


                  I now use a Canon Vixia AVCHD... still going to a DVD... the picture quality of the DVD is MUCH better than anything I created before, since I am starting with a higher bit depth and letting CS5 take care of the downsizing and downrezzing at the end of the process

                  • 6. Re: Down-Converting 1080p to 720p
                    Jim_Simon Legend
                    Or is it going to look the same if I work in 720 right from the start?


                    That'd be my guess.

                    • 7. Re: Down-Converting 1080p to 720p
                      dukeorock Newcomer

                      I've been shooting 1080 AVCHD on a Panasonic HMC 40...recently started loading the footage into 720 sequences with really great results.

                      • 8. Re: Down-Converting 1080p to 720p
                        Dave Merchant Mythic

                        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.

                        • 9. Re: Down-Converting 1080p to 720p
                          DoctorBongo Newcomer

                          When practical shoot at the native camera resolution. Edit native. Do any scaling at the end of the process.

                          • 10. Re: Down-Converting 1080p to 720p
                            Bill Gehrke Rockstar

                            I have a related but slightly different question.  I will be videoing my grandson's high school football games with my Sony NX5U.  Is there any advantage using 720p over 1080i for action events.  Last year I did not experiment and try 720p,  I used 1080i and produced primarily DVD's and an occasional BD-R

                            • 11. Re: Down-Converting 1080p to 720p
                              John T Smith Legend

                              Canon Vixia HFS100 AVCHD MPEG4-AVC / H.264

                              http://forums.adobe.com/message/2765679 Jeff Bellune sez...
                              -Use 60i for high-motion, action and sports scenes.
                              -24p is good for low-motion, film-like storytelling scenes.
                              -30p is virtually worthless
                              • 12. Re: Down-Converting 1080p to 720p
                                Jim_Simon Legend
                                any advantage using 720p over 1080i for action events.


                                Yes.  Much better temporal resolution.  1080 is 30 interlaced frames, 720 is 60 progressive frames.

                                • 13. Re: Down-Converting 1080p to 720p
                                  Bill Gehrke Rockstar

                                  Thanks Jim, I thought that should be the case.

                                  • 14. Re: Down-Converting 1080p to 720p
                                    Ironbird Studios

                                    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?