8 Replies Latest reply on Jan 22, 2012 6:46 PM by Jim_Simon

    Quality issue with ProRes

    Alex Bundy

      Hi there,

       

      I have an issue with premiere, and despite all I read, I can't understand why.

      Hoping you can help me

       

      So, I have a ProRes file that I'm importing in premiere CS5 (7 x64).

      I drag it on the timeline icon to create one with same settings, and I export it to a lossless codec.

       

      The export file should be similar as the file source, but it's not.

      It's really bad.

       

      So I did the same in Edius, Procoder, and tgcmpeng.

      And it's not similar neither to the source, but it's really better than premiere export.

      Actually, these three software give same resuts.

       

      I understood that my ProRes file is 10bit, and the lossles codec 8bit, so it's normal to get something lightly different.

      But what I don't understand, is why Premiere export is not as good as the others.

       

      I made some grabs for an exemple, and I just levelled up the gamma in photoshop to perfectly see differences.

       

      Here's the original ProRes

      Pro-res-original.png

       

      Here's the Edius export

      Export-Pro-res-from-Edius.png

       

      And here's the premiere export

      Export-Pro-res-from-premiere.png

       

       

      As you can see, this last one has a lot of banding.

       

      If you're interested in making test, here's a link of two secs from the original ProRes :

      https://rapidshare.com/files/668653597/Loki.mov

       

       

       

      Thanks for your help.

        • 1. Re: Quality issue with ProRes
          shooternz Level 6

          and I export it to a lossless codec.

           

          What would that codec be?

          • 2. Re: Quality issue with ProRes
            Alex Bundy Level 1

            I tried with Lagarith, huffyuv, and canopuss lossless.

            Always same reults with premiere.

            • 3. Re: Quality issue with ProRes
              joe bloe premiere Level 5

              No problem here...

              Loki.png

              I imported your clip to Pr, exported the first frame as a .tif then converted to a .png in Photoshop.

               

              I have also encoded a Lagarith .avi with no banding at all:

              lagarith.png

              • 4. Re: Quality issue with ProRes
                Alex Bundy Level 1

                Thanks for you test Joe

                 

                Funny thing, your exported frame five the same resuls as your lagarith.

                It's not the case for me.

                 

                Then, I levelled up your grab as I did for the edius one, and this is what I get :

                Joe's-grab-levelled-up..png

                It's far better than mine from premiere.

                But still as not as good than the one from edius.

                 

                Anyway, you have different results than me, and that's what matters.

                 

                Could you tell me  which windows are you using, and your quicttime version ?

                 

                Thanks again

                • 5. Re: Quality issue with ProRes
                  joe bloe premiere Level 5

                  Win7 64

                  Quicktime v7.6.9 (1690.9)

                   

                  The image you downloaded was compressed to .png from the original .tif export.

                  The .tif was too big to post.

                  • 6. Re: Quality issue with ProRes
                    Alex Bundy Level 1

                    Ok thanks,

                     

                    I will try to install this quicktime version tomorrow.

                    Maybe its the reason of this issue.

                     

                    Thing is, I still get better results from Edius and procoder.

                    So I don't get it.

                    • 7. Re: Quality issue with ProRes
                      Alex Bundy Level 1

                      So I made some test with your quicktime version, and it doesn't change anything.

                       

                      But I think I've figured it out.

                       

                      It's simple :

                      Premiere import the yuv file in 10 bit is in RGB color space.

                      Between import and export to lossless codec, it makes two things :

                       

                      - Convert the input YUV to RGB.

                      - Convert the 10 bit to 8 bit.

                       

                      Result is a video file RGB 8 bit.

                       

                      You can of course chose a YUV codec to force export in YUV 8 bit.

                      And you'll get better results, but the conversion YUV=>RGB=>YUV will slightly change colors.

                       

                      That's why it's not as good.

                       

                      To prove it I made a different test :

                       

                      - I export the 10 bit YUV ProRes file to uncompressd 10 bit YUV.

                      and result was perfect, but with slight change of colors (YUV=>RGB=>YUV)

                       

                      I think the CS5 new feature of working YUV files in RGB space is the reason of all.

                      And it has mportant drawback.

                       

                      I hope CS6 will allow you to chose your space color workspace.

                      • 8. Re: Quality issue with ProRes
                        Jim_Simon Level 8

                        To the best of my knowledge, Premiere Pro will only force an RGB conversion if it needs to.  For example, if you have applied an effect that requires it.

                         

                        If you start with a YUV clip (as most everyone does these days), use only YUV effects, and export to a YUV format, PP should keep it in YUV space the entire trip.

                         

                        I would also not expect any significant alteration going from YUV to RGB.  The formula isn't perfect, but the errors are generally below the level of human vision.