6 Replies Latest reply on Aug 18, 2014 6:42 PM by Rick Gerard

    Weird render output, when rendering 4K footage to 1080p

    alvius_88

      Hi,

       

      I have a 4K footage (prores 422 with .mov format) and would like to convert it to 1080p ( with .mov format with photoJPG codec).

       

      So I import the 4K footage onto adobe after effect and render it to 1080p. The output file has weird effect as shown in below picture.

      Please note that I render using best possible setting as well.

       

       

      Weird effect of rendered 1080p: "wave of lines" seen at the area of sky and mountain. The lines are constantly moving like "water ripples" effect.

      8-19-2014 2-48-51 AM.jpg

       

       

      Original 4K footage: no "wave of lines" seen.

      8-19-2014 2-50-48 AM.jpg

       

      Could you guys kindly tell me how to solve this problem? It is really appreciated.

        • 1. Re: Weird render output, when rendering 4K footage to 1080p
          Szalam Adobe Community Professional & MVP

          What happens if you use the PNG codec instead of the Photo-JPEG codec?

          • 2. Re: Weird render output, when rendering 4K footage to 1080p
            alvius_88 Level 1

            Hi Szalam,

             

            I think the lines are gone but I'm not too sure, because the video really lags and it plays only every 5 seconds. The frame is constantly stucked in between.

             

            Please help me out, thanks a lot in advance.

            • 3. Re: Weird render output, when rendering 4K footage to 1080p
              Szalam Adobe Community Professional & MVP

              The reason it is lagging like that is the data rate of the video is too high for your hard drive to handle.

               

              The reason those lines show up in the Photo-JPEG file is that the Photo-JPEG codec is a lossy codec. It compresses things so you will see some quality loss in certain areas. The subtle gradation of the sky is, unfortunately, an area where you will see compression artifacts.

               

              I would suggest the lagarith codec, DNxHD codec (free from Avid), or the Cineform codec (free from GoPro) as your intermediate codec. The data rate will be lower than the PNG codec and it will hopefully be less compressed than the Photo-JPEG codec.

              • 4. Re: Weird render output, when rendering 4K footage to 1080p
                Rick Gerard Adobe Community Professional & MVP

                A couple of questions for you. First are you resizing the output in the output module? If so, don't do that, the scaling algorithm the output module uses is IMHO horrible.


                Second, what are the quality settings on your photo JPEG? If they are not 95% or better you're probably just seeing compression artifacts.


                For best results with the minimum noise I would create a new 1080 P composition, drag the 4K footage into that comp, resize to fit horizontally, then apply unsharp mask and/or filters to reduce the amount of noise and add some detail to the footage. The project would be set the 32-bit and I would render not to photo JPEG but to JPEG 2000 or PNG QuickTime. In both cases quality would be set to 90% or better.


                A faster option would be to use the Adobe Media Encoder. Bring your 4K footage into the AME use a 1080 P preset and render to JPEG 2000. Manually scale down the footage so that it fills the frame and does not distort. I have found that the Adobe Media Encoder has better scaling algorithms than the output module when scaling down footage.

                • 5. Re: Weird render output, when rendering 4K footage to 1080p
                  alvius_88 Level 1

                  Hi,

                   

                  I need the photo-JPEG codec because it is a requirement from istockphoto website when submitting footage. I don't think they accept JPEG 2000 as shown on this page: Stock Photography: Search Royalty Free Images & Photos - iStock

                   

                  I've also tried the 1080p composition and dragging 4k footage in and scale it down, then apply and render everything at best setting, still the same problem, even when using the Adobe Media encoder as well.

                   

                  -____-"

                  • 6. Re: Weird render output, when rendering 4K footage to 1080p
                    Rick Gerard Adobe Community Professional & MVP

                    There must be some noise in your 4K footage. If you can post about 60 frames of a clip in native 4K I'll give it a try.

                     

                    By the way, you resized your screenshots so we can't see any problem with them. Scaled down screenshots are basically useless. The forum will accept full frame images, they are just scaled when embedded by html codes.