7 Replies Latest reply on May 13, 2011 4:55 PM by Shadreck Rukweza

    AVCHD PIXELATION

    Shadreck Rukweza Level 2

      Following my recent thread on Sequence Presets I decided to edit my footage using the Matrox 1920 x 1080i 25 fps preset. My footage was capture in two formats, AVCHD (Panasonic HMC151) & HDV (Canon XH A1).  All the footage is 1080 50i.

       

      Using my Matrox RT X2 I created a Matrox sequence which is 1920 x 1080i 25fps. However my surprise is that I see huge blocks of pixelation on the AVCHD files, could be a frame or two of these by they are truly visible and I cannot proceed with such motion artefacts. Do you know how I can edit this staff without the pixelation.

       

      The project is now overdue and I need to get cracking as soon as possible.

       

      PS

      The image from the Canon XH A1 is far superior than the HMC 151. I borrowed this camera from the Uni, but the advantage is just workflow with Premiere Pro CS5 but with Final Cut Pro, th log and transfer takes more than real time, because FCP does not edit the AVCHD files. I wouldn't recommend the HMC 151 at the moment until the tapes have ceased exist.

        • 1. Re: AVCHD PIXELATION
          Shadreck Rukweza Level 2

          Hello again!

           

          I forgot to say that this is a multicam window showing this, a non multicam windo does not show any pixelation at all. What could be the problem here? Did anyone experienced this before?

           

          Thank you.

          • 2. Re: AVCHD PIXELATION
            Colin Brougham Level 6

            The Multicamera Monitor plays at fractional resolution by default; there is no way to set it to full resolution. With AVCHD and similar media, it can look pretty chunky. Since realtime playback is more important than full resolution playback in this instance, that's a necessary concession. Playing back the sequence in the Program Monitor will look correct (at full resolution) as will export.

            • 3. Re: AVCHD PIXELATION
              Shadreck Rukweza Level 2

              I immediately thought so, but its all on my Matrox preview monitor (26") which can display all four camera. Do you know if there is a trick to match the cameras in post, at least close. I have tried with Matrox Colour Correction but still, the AVCHD is just not that colouful here.

               

              Thanks Colin

              • 4. Re: AVCHD PIXELATION
                ectobuilder50

                I am assuming that "multicam window" means that you are outputting the image to an external field monitor?

                 

                If so, most older or underpowered camcorders that output to an external field monitor will downgrade the quality.

                 

                For instance, the Canon T2i, T3i, T3, 60D and 5D Mark II will downgrade the resolution to a field monitor when you press record (720 x 480) with color sampling of 4:2:0 which isn't bad but they might further compress the color down such that the bandwidth is less than 10Mbps (keep in mind that AVCHD is spec'd at 24Mbps max).

                 

                A higher-end camcorder such as the Sony NEX-FS100 for instance will output at full resolution and at 4:2:2 color sampling via HDMI.  To maintain full quality I would recommend a camcorder that supports the newer HD-SDI 3G output which provides dual-link (twice the bandwidth) to proper telecine 24p (23.97fps) signals.  Other camcorders such as the Sony PMW-F3 will output 4:4:4 uncompressed color sampling via HD-SDI 3G!

                 

                Therefore check your camera/camcorder's specifications to see how it is outputing the image/video to a field monitor.

                 

                Also, field monitors are inherently lower in resolution, most of them are 800 x 480, that could also amplify the situation.

                 

                Another thing to consider is how you are taking the picture/video.  Make sure you have the correct exposure.  Adjust gain (ISO sensitivity) last.  Try to adjust aperture first while keeping the shutter at 1/60.  Then adjust shutter and finally adjust gain.  I'm assuming you are using manual exposure here.

                 


                Some cameras/camcorders lack the processing abilities of higher-end ones.  The Canon DSLR's for instance adds lots and lots of moire to fine patterned objects.  In this case there is nothing you can do other than to avoid filming such objects.  The Sony PMW-F3 on the other hand does not since it has a highly capable Optical Low Pass Filter and overall processing.

                 

                If you find that your camcorder is indeed underpowered, but can output the correct resolution, then you may want to try to add an external recording device as this can increase the quality such as the Atomos Ninja or AJA Ki Pro nanoflash.  This will bypass the camcorder's internal encoding and go straight to these higher quality recording devices.  Just be sure you can work with ProRes files as this seems to be the trend with external recorders.  ProRes offers up to 4:2:2 uncompressed quality while staying light on the processing load of your workstation.

                • 5. Re: AVCHD PIXELATION
                  Shadreck Rukweza Level 2

                  Thanks for your post mate.

                   

                  I might say that your comments are far beyond the scope of this editing process I am undertaking. I am just wandering if you have used Multicamera editing in Adobe CS5, and above all talking about 35mm cameras in this thread is just not right, because we cannot compare a cat and a Bengal Tiger here.

                   

                  Will be very happy to be pumped with more technical staff here as you demonstrated.

                   

                  Thanks my mate.

                  • 6. Re: AVCHD PIXELATION
                    ectobuilder50 Level 1

                    Oh I see, do you mean editing a sequence such that you get a picture-in-picture format?

                     

                    If that is the case then having the most uncompressed video format is desirable because when you go to resize that video to a non-native resolution and scale then you are by definition adding artifacts.  The software has to then throw away/add information in order to accomodate the rescaled video.  Hence, if your video is being recorded at say 4:2:0 as opposed to 4:2:2 (i.e. with less information to begin with) then this would add to your problems).

                     

                    So for instance if I had a Canon EOS 60D and I took a 30 second clip of an exterior fence, there is a good chance that the 60D is going to produce moire in that fence.  And that moire in a resized scale in Premiere Pro will look even worse!  If however I took the NEX-VG10 that doesn't produce moire then the rescaled video will look better than in the first scenario.

                     

                    So personally I find that the initial quality of the capture can further enhance the final editing quality in Premiere Pro.

                    • 7. Re: AVCHD PIXELATION
                      Shadreck Rukweza Level 2

                      ectobuilder50 wrote:

                       

                      Oh I see, do you mean editing a sequence such that you get a picture-in-picture format?

                      Thanks for your response. In this case I am talking about multicamera editing. Multicamera editing is not PIP and therefore cannot be related to your findings using the colour profiles you providing. If you read the whole thread, then I would like to say that the question has been answered. We are more than happy to hear your experience with DSLRs and Premiere Pro CS5 etc, but the original question has been solved and it does not require anyone complicating their findings, as you cannot replicate the first issue, due to the hoard of cameras you have given explanation about.

                       

                      I would like to believe that you still got a learning curve to climb inorder to understand Premiere Pro CS5 and multicam editing. Quote me wrong there if I am.

                       

                      Thank you.