5 Replies Latest reply: Apr 15, 2013 5:02 AM by andy-mario RSS

    h264 compression generate blocks?

    andy-mario Community Member
    andy-mario Apr 2, 2013 10:47 PM

      I am converting a prores 4444 master to h264. The movie was edited in premiere, then graded in speedgrade and rendered in prores 4444.
      In the original movie there is some noise, it was shoot at high iso because it's slow motion. However, it looks very good, with an acceptable quantity of noise in the dark background.

       

      The resulting h264 is full of really noticeable block artifacts, and vignettes suffering heavy banding, and blocky pixels make the problem more visible.

      I also noticed a color shift from green-ish to blue-ish.

       

      I tried every setting, even 20mbps 5.1 with keyframes every 1 frame.

       

      Please see attached screen capture for an example, notice the blocky content on the right.

      I'm afraid that uploading this on youtube will make it even worse.

       

      Do you have any suggestion on a better way to encode the file?

      ame.jpg

      ame2.jpg

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        • 1. Re: h264 compression generate blocks?
          SAFEHARBOR11 Community Member
          SAFEHARBOR11 Apr 5, 2013 8:26 AM (in response to andy-mario)

          I didn't reply yesterday, hoping someone else would have a better answer. Here goes. What are the Export settings - can you post a screen grab?

           

          Anytime you have a background that is almost a solid color, such as sky or your background, banding can be an issue when working with highly-compressed export codecs. There are just so few steps between the colors that it is difficult to achieve a smooth gradient with the compression being used.

           

          Thanks

           

          Jeff Pulera

          • 2. Re: h264 compression generate blocks?
            Rallymax-forum Community Member
            Rallymax-forum Apr 8, 2013 2:46 PM (in response to SAFEHARBOR11)

            SAFEHARBOR11 wrote:

             

            I didn't reply yesterday, hoping someone else would have a better answer. Here goes. What are the Export settings - can you post a screen grab?

             

            Anytime you have a background that is almost a solid color, such as sky or your background, banding can be an issue when working with highly-compressed export codecs. There are just so few steps between the colors that it is difficult to achieve a smooth gradient with the compression being used.

             

            Thanks

             

            Jeff Pulera

            That's simply not true.

            The bundled h.264 encoder just makes very poor decisions when it comes to the bit budget.

            It's not appropriate for me to mention my 3rd party h.264 encoder but look around this forum and you'll find it talked about.

            • 3. Re: h264 compression generate blocks?
              Matt Dubuque Community Member
              Matt Dubuque Apr 8, 2013 4:18 PM (in response to Rallymax-forum)

              rallymax, does your critique extend to the standalone AME as well?

               

              Matt

              • 4. Re: h264 compression generate blocks?
                Rallymax-forum Community Member
                Rallymax-forum Apr 8, 2013 4:33 PM (in response to Matt Dubuque)

                Premiere Pro and AMEpull from a common set of decoders and encoders, so yes, the h.264 encoder is the same.

                 

                best regards,

                 

                Rallymax

                • 5. Re: h264 compression generate blocks?
                  andy-mario Community Member
                  andy-mario Apr 15, 2013 5:02 AM (in response to andy-mario)

                  End of story, it was problem of source movie. It has a lot of grain (rallenty at high iso with a low bitrate mxf codec) and I put strong vignettes in grading, that added to the source noise, created a lot of artifacts and blocks, specially over the vignettes. The dark and flat background made it worse.

                   

                  As a solution I did again the entire color correction keeping it more subtle and with less vignetting, until I got a decent result. AME this time did a good job, but with a third party sofware I did an x264 and looked better. Usually I don't need 3rd party, ame do a good job.

                   

                  Thanks for all your suggestions, I learned that in these situations (flat background, not perfect lighting) it takes a lot of trial and error to get a good h264!