4 Replies Latest reply: Apr 19, 2014 12:27 AM by Fuzzy Barsik RSS

    Avid DNxHD codec artifacts

    WShawn Community Member

      Hello:

       

      I been sent some Quicktime clips that have been compressed with the Avid DNxHD codec for use in an After Effects project .  The clips are exhibiting magenta artifacts in bright white areas of the video when my project is set to 16 bit color depth.  These artifacts go away when the bit depth is set to 8 bpc.  It doesn't matter whether the Quicktimes are tagged as being in the HDTV Rec 709 profile or sRGB.  It doesn't matter whether my working space is set to HDTV Rec 709 or sRGB.  The artifacting always appears in 16 or 32 bpc and disappears when set to 8 bpc.

       

      The codec is installed on my system (Mac OS 10.7.5), and I haven't had problems with it in the past.  It looks like the Avid Codecs are 2.3.7.  Maybe they're out of date?

       

      The artifacting appears in both AE CS6 and AE CC.

       

      Any thoughts?

       

      Thanks.

       

      Shawn Marshall

      Marshall Arts Motion Graphics

       

      Avid_DNxHD_Codec_Color_Problems.jpg

        • 1. Re: Avid DNxHD codec artifacts
          Mylenium ACP/MVPs

          This usually only happens when the person encoding the clips has allowed super-whites, which messes with the internal compression, meaning thge error must not necessarily be on your end. Either way, without having the exact setting or even a test clip to check, nobody can say much beyond that.

           

          Mylenium

          • 2. Re: Avid DNxHD codec artifacts
            WShawn Community Member

            Thanks for the reply.

             

            I believe I told the Avid editor to export the clips "Same as source."  I don't know how the original clips were brought into his Avid.

             

            As far as I can tell, 2.3.7 is the latest version of the DNxHD codecs.

             

            When I bring these clips into Premiere Pro the video appears pure red.  If I run the clip through After Effects (8-bit color space) and output with various DNxHD codecs the clips look fine in Premiere Pro.

             

            Here are the specs of the problematic clip in Premiere Pro:

             

            Type: QuickTime Movie

            File Size: 121.9 MB

            Image Size: 1920 x 1080

            Frame Rate: 29.97

            Total Duration: 00:00:04:20

            Pixel Aspect Ratio: 1.0

             

            QuickTime Details:

            Movie contains 1 video track(s), 0 audio track(s), 0 closed caption track(s), and 1 timecode track(s).

             

            Video:

            There are 140 frames with a duration of 25/749ths.

             

            Video track 1:

            Duration is 0:00:04:20

            Average frame rate is 29.98 fps

             

            Video track 1 contains 2 type(s) of video data:

             

            Video data block #1:

            Frame Size = 1920 x 1080

            Compressor = 1080p/29.97 DNxHD 145 8-bit

            Quality = Most (5.00)

             

            Video data block #2:

            Frame Size = 1920 x 1080

            Compressor = 1080p/29.97 DNxHD 145 8-bit

            Quality = Most (5.00)

             

            Timecode:

            Timecode track 1 contains 1 type(s) of data:

             

            Timecode data block #1:

            Start Time = 01:00:28:10

            Reel name =

             

             

            Here's a link to a zipped file (18MB) containing 20 frames of the offending clip.  Note that there's a frame of white at the beginning of the clip.  This frame appears white in Premiere Pro, but the video content of the product displays as pure red in PP.

             

            http://marshall-arts.net/Support/DNxHD_Excerpt.mov.zip

             

            Cheers.

             

            Shawn Marshall

            Marshall Arts Motion Graphics

            • 3. Re: Avid DNxHD codec artifacts
              WShawn Community Member

              Another aspect:  If I run the Avid DNxHD clip through Adobe Media Encoder, exporting it to another DNxHD codec or ProRes 422 the resulting clips display the magenta artifacting in After Effects, regardless of whether the project is set to 16-bit or 8-bit.  It seems to be passing through whatever is causing the artifacts.

               

              If I convert the clip through Quicktime player the magneta artifacts go away in AE, both 8 and 16-bit project.

               

              Shawn

              • 4. Re: Avid DNxHD codec artifacts
                Fuzzy Barsik Community Member

                As Mylenium said, the issue is related to encoding footage, which contains superwhites. When you set your project bit depth to 8-bit, all superwhites are automatically clipped to 1.0.

                 

                See this thread on encoding to DNxHD in MOV container via Adobe products. Probably the same or similar rules are correct for encoding to DNxHD in other applications.