9 Replies Latest reply on Jul 4, 2009 8:05 PM by Jeff Bellune

    Mixing different size HD clips - what size to chose?

    mickkeay

      Hi All - This is not ideal, I know, but I have a project (for eventual bluray output)  and my hd footage is roughly a 50/50 mix of  1280 x 720 mjpeg  and 1440 x 1080i AVCDD.  CS4.1  is happy with all footage. I want to mix and hop from one to other for the final output.

       

      I dont know if I should use a 1280 x 720 sequence and scale down the 1440x1080  or start with 1440x1080 and  scale up the 1280x720 on timeline.

       

      Or should I be making a shed load of extra work with lots of individual sequences and nesting - and if so what size the 'master' sequence.  I am hoping for some pointers before I go and experiement

       

      Thanks

        • 1. Re: Mixing different size HD clips - what size to chose?
          Harm Millaard Level 7

          Blu ray is 1440x1080 (PAR 1.33) or 1920x1080 with square pixels. Your 1280x720 needs to be uprezzed anyway and will lose significant quality. To add this quality hit to your 1440x1080 footage by first downrezzing and then uprezzing seems undesirable. Better limit the quality hit to only your 1280x720 footage.

           

          So use a 1440x1080 preset.

          • 2. Re: Mixing different size HD clips - what size to chose?
            Jeff Bellune Adobe Community Professional

            1280x720 is also a Blu-ray legal frame size.  It depends on the frame rate.  1280x720 is supported at 24 fps progressive, 50 fps progressive, and 59.94 fps progressive.

             

            It is always better to scale down than scale up, so a 1280x720 sequence is a better choice for final output.  But since all 1280x720 BD-supported frame rates are progressive, your 1080i footage will need to be deinterlaced.  My recommendation is to create a 1440x1080i sequence that matches your source footage, then nest that sequence inside of the 1280x720 sequence and scale it down.

             

            Set both of the sequences to Maximum Render Quality, which will automatically set the AME to MRQ when you export.  When you scale and/or deinterlace in Pr, you must choose MRQ or you will get genuinely poor output.  Be aware that MRQ takes a loooong time to render.

             

            -Jeff

            • 3. Re: Mixing different size HD clips - what size to chose?
              mickkeay Level 1

              Thank you guys -much appreciated  so just to check for understanding...  (the 1280 is 24 frame btw - from a D90 dslr and quite filmy, dreamy and pleasing actually - really narrow DoF. but I digress)  So.. 

               

              Harm reckons to set 1440 x1080i preset to match that footage, upsize the 1280 where used on the timeline and then output from that with MRQ

               

              Jeff reckons to (essentially)  do same, deinterlacing the 1440x1080i  (assuming from a right click.. deinterlace of each instance on the timeline?)  but then to then have a new 1280 x 720 (final) sequence and nest the above 1440 in it, scaled down and make that the final output before over to encore and out to bluray via encore - or whatever.

               

              Have I understood correctly?  Will give both a go and report back if so

              Thanks again

              Mick

              • 4. Re: Mixing different size HD clips - what size to chose?
                Harm Millaard Level 7

                You understood correctly. Be aware however that deinterlacing in PR does not give very good results. Secondly, with Jeff's approach you end up with 1280x720 footage, which when shown on a full HD screen is uprezzed to 1920x1080 and then you suffer again a quality hit with the 1440 footage. Try both ways and see what you like best.

                • 5. Re: Mixing different size HD clips - what size to chose?
                  Jeff Bellune Adobe Community Professional

                  You should also test a short segment where you don't deinterlace via the field options on each clip.  Rather, you leave the nested sequence interlaced and choose No Fields (Progressive) in the Video tab of the AME export settings.  That lets the AME and Max Render Quality handle the deinterlacing, which may be better than having the Field Options for a clip handle it.

                   

                  I haven't tested that workflow yet, having spent a lot of time instead on scaling from HD to SD, so you will be providing good info for everyone if you do the test and report back.

                   

                  -Jeff

                  • 6. Re: Mixing different size HD clips - what size to chose?
                    mickkeay Level 1

                    Ok many thanks guys - all understood and I will give the options a go over next few days with a few small sequences and some BD-REs

                     

                    On Harm's last point regarding me ending up with a 1280x720 to go to bluray with  (and another slight digression) ....  is it not true that most broadcast HD is actually 1280 x720  (I am in UK so eg BBC HD for example?)    So all the Big Screen TV advertising puff .... 1920 full HD  ... 1080p  blah blah  is all pretty irrelevant  unless your source can match that (only from a bluray disc presumably)  Reason I mention is because the sat or cable HD stuff still looks pretty good to me. Thanks again - Mick

                    • 7. Re: Mixing different size HD clips - what size to chose?
                      mickkeay Level 1

                      this correct answer business... can I not give a correct answer to both Jeff and Harm? You have both been really helpful

                      • 8. Re: Mixing different size HD clips - what size to chose?
                        Harm Millaard Level 7

                        Technically, no. And since only you can decide what the best results will be with your source material and a form of suggested ancoding on your BR player on your full HD panel, only you can decide if there was even a correct answer. If you feel there was no correct answer, you can give points for helpful answers. Or you can 1 correct answer and 2 helpful answers to another.

                         

                        Apart from this points business, I would be interested to know if you can see a quality difference between broadcast material from your SAT receiver and your own full HD material (my suggestion) on your panel. I'm not familiar with the UK practice of broadcasting HD material, but my understanding is that Discovery and some others broadcast at 1920x1080. That should be the signal from the SAT receiver. Over cable things may be completely different because of bandwidth.

                        • 9. Re: Mixing different size HD clips - what size to chose?
                          Jeff Bellune Adobe Community Professional

                          Give the points to Harm.  I already have a Community Expert badge and a Moderator hat.

                           

                          My cable HD is all 720p here in the southeast USA.

                           

                          -Jeff