5 Replies Latest reply on Feb 9, 2012 7:32 AM by Dave LaRonde

    Interlaced Video and AE - Artifact Issue

    EckleySP Level 1

      I am on CS5.5 running on a Win7 64 machine. 

       

      Here's my workflow:

       

      I have content from two cameras - all clips are AVCHD 1080i30.   I import them into Premiere Pro and create a multi camera sequence where I edit the two clips into 'one'. 

       

      I found you cannot simply run this sequence into AE because AE can't handle the multi-cam sequence - not sure why, but OK, it can't.  So, I take the multi-cam sequence and render it out into a WMV file which I then bring into AE.  As an alternative, I have also nested the multi cam sequence into another sequence (interlaced) and used dynamic link to take into AE. 

       

      In any case, in AE I apply several effects:  Levels, Curves, mostly, and then render it back out as another AVI file for inport into PP. . .  (or if dynamically linked, it's updated in PP). 

       

      The AVI file, when viewed on a PC monitor, has a lot of horizonal artifacts which would seem to indicate an issue with it being interlaced.   If I take the same AVI file and create a DVD with Encore, the same artifacts appear when viewed on a TV. 

       

      Its worth noting that if I take the clip from PP and dymaically link it to Encore and create the DVD, it looks fine. 

       

      So, it leads me to think that the Levels and Curves effects are added the artifacts.  I am crushing blacks to give it more contrast - that alone seems to create noise in the black areas of the composition (which is not there when you view the video that has not gone through AE).  I can only assume about the horizonal lines that are predominate in the video. 

       

       

      I have no idea what I'm doing to cause the artifacts from AE - if it's the effects, the imported file or if I should make adjustments to the exported file.   I have tried to keep the interlaced format consistant throughout. 

       

      If anyone knows of rules I'm breaking that might cause this, please let me know,

       

       

      Scott

        • 1. Re: Interlaced Video and AE - Artifact Issue
          Mylenium Most Valuable Participant

          I have no idea what I'm doing to cause the artifacts from AE

           

          Erm....

           

          So, I take the multi-cam sequence and render it out into a WMV file which I then bring into AE. 

           

          You are rendering to a compressed format. All forms of WMV are compressed, even the so-called Uncompressed. You're ruining your color information and introducing block artifacts. Use a different intermediate format like good old Quicktime Animation or image sequences. Of course there may also be other things going on like you screwing up your fields with wrong footage interpretation and agressive settings for effects in 8bpc causing banding and quantization...

           

          Mylenium

          • 2. Re: Interlaced Video and AE - Artifact Issue
            EckleySP Level 1

            Seemed to have fixed the issue. . .   I still have to make a DVD, but I can tell playing the AVI file out of AE that the artifacts are drastically reduced.  

             

            I do have a further question (somewhat unrelated).   I render out using AE standard 'lossless' setting (which is an AVI file).   The short test clip I use renders to a file that is about 466,000 KB.  I changed the bit rate from 8 to 16 and re-rendered and then changed it to 32 and rendered again and the file sizes of all three are the same.  I've never used anything but 8, but I was under the impression that the higher bit rates produced larger files and better quality.  

             

            Any lesson in this area would be appreciated. . . .

             

            Scott

            • 3. Re: Interlaced Video and AE - Artifact Issue
              Dave LaRonde Level 6

              EckleySP wrote:

              I render out using AE standard 'lossless' setting (which is an AVI file)....   I changed the bit rate from 8 to 16 and re-rendered and then changed it to 32 and rendered again and the file sizes of all three are the same.

               

              When you say 8, 16 and 32 bits you're talking about changing the AE project settings, right?  They don't affect the number of color bits in any given codec. 

               

              I've been told that one of the virtues of working in a high bit depth in AE is that it tends to smooth out the look of gradients, glows, etc. even if you're rendering to an 8-bit codec.  I've never tested this personally.

              • 4. Re: Interlaced Video and AE - Artifact Issue
                EckleySP Level 1

                Well, it remains somewhat of a mystery then.  One more question - somewhat related. . . 

                 

                I was experiencing the same artifacts regardless of whether I was importing the WMV file or using dynamic link.  Apparently with dynamic link, there is similar compression being applied in the 'transfer' to AE from PP.  Do you, or anyone, know what's going on internally with dynamic link in terms of 'what format' is being imported into AE? 

                • 5. Re: Interlaced Video and AE - Artifact Issue
                  Dave LaRonde Level 6

                  It might not be the compression alone, but interlacing.  In Ae, you may have to separate fields.  I'm an FCP guy, so I'm unsure how Premiere projects come in.  If footage appears in the project window -- perhaps in a folder, try interpreting the footage as upper field first.