8 Replies Latest reply on Feb 16, 2011 4:42 PM by Colin Brougham

    Battling Hardware MPE, Episode 1: Cropping on Export

    Colin Brougham Level 6

      This is likely going to be a series of posts about some of the--shall we say--quirks I've encounted when trying to work with hardware acceleration/MPE with CS5. I should preface this by saying that I am, at this time, using a GTX 480 which is obviously unsupported, so I'm willing to accept that any of what I've come across is due to this fact; however, I'm pretty sure that these issues are endemic to hardware accelerated MPE, in general.

       

      The first quirk I've found is that when exporting from Premiere with GPU acceleration activated, using the Export button, while cropping the source using the export crop function, the resulting encoded file is not properly rendered. Specifically, this set of variables results in black bars in the encoded video, seemingly the result of the "Scale to Fit" parameter being ignored. The source sequence type and material as well as the destination format do not seem to matter; originally, I thought this was an issue with the H.264 encoder, which I use for exporting small emailable spot reviews, but I've confirmed it with other formats like Flash and AVI as well.

       

      Since a picture is worth 1000 words, what follows are four screenshots illustrating the two variables I'm testing--namely, GPU acceleration and direct export vs. AME queue. For reference, the source sequence is a standard DV NTSC sequence, with a mish-mash of graphics and footage, and I'm exporting to a Lagarith AVI, 320x240, progressive, cropping 12L,4T,12R,4B, Scale to Fit. No, I wouldn't ordinarily export to such a file, but it's the same regardless of format, scaling, or cropping values.

       

      GPU Acceleration off, sent to AME queue:

       

      gpu-off-crop-queue.png

       

      GPU Acceleration off, direct export:

       

      gpu-off-crop-export.png

       

      GPU Acceleration on, sent to AME queue:

       

      gpu-on-crop-queue.png

       

      GPU Acceleration on, direct export:

       

      gpu-on-crop-export.png

       

      In the last one, you can clearly see the issue. Since the aspect ratio of the rendered file isn't changing, it would appear that the Scale to Fit option is not necessarily being overriden, but it's almost as if the crop values are being reapplied and creating the black bars.

       

      So, if this is due to hardware MPE, why isn't it appearing when sending the export to the AME queue? Well, here's my theory: hardware acceleration/rendering isn't being used when the export is sent to the queue! Check out the first three images: they are exactly the same. I would expect this of the two "GPU off" screenshots, but not of the "GPU on" screenshot.

       

      Now compare the two "GPU on" images; the one showing the cropping bug is noticeably sharper, and it shows the telltale signs of the linear light processing that hardware MPE is supposed to enable (which is another issue I'll cover later). You can see the blue light rays coming off the sparks much more clearly in the last image (again, not that I like this, or that it should be that way, but it's an indicator that MPE is working).

       

      So what the heck is going on here? Is this a bug, a quirk due to me using an unsupported card, or is this a "feature" in much the same way that linear light processing of GPU accelerated MPE is a feature? This would be a pretty simple thing for anyone to test: just create a DV sequence, throw anything in it (color bars would work), crop 8 pixels off the sides in the export window, and use the Export button to render to any particular format at 320x240 (I've confirmed this with other frame sizes, by the way).

       

      Hoping to get to the bottom of this... thanks for any discussion this may spark.

        • 1. Re: Battling Hardware MPE, Episode 1: Cropping on Export
          Andy Urtu Level 1

          Yep, Huston we have a problem.  I can reproduce your example. I have a GTX285.  Everything works great on my setup.  I have MPE enabled.

           

          I also tried a variation of your example.  I exported a 1280x720 image to a DV 720x480 Wide format.  I cropped 8pix from the TOP and Bottom so no black bars should be seen..

          If exported via Queue, fine.  If exported directly the resultant image is cropped to 4x3.

           

          Exported via Queue

          16x9.JPG

           

          Exported directly

           

          4x3.JPG

          • 2. Re: Battling Hardware MPE, Episode 1: Cropping on Export
            Colin Brougham Level 6

            Andy,

             

            Thank you for taking the time to test and report. Your post would seem to indicate some other bizarre behavior with MPE on export; I'm starting to wonder if it always defaults to a 4x3 export, regardless of source or settings!

             

            More testing, I must do...

             

            Again, thank you!

            • 3. Re: Battling Hardware MPE, Episode 1: Cropping on Export
              Colin Brougham Level 6

              Thanks again, Andy--I did some more testing based on your findings. Here's what I've discovered, with hardware MPE enabled:

               

              1. If I export to a DV Widescreen AVI from a DVCPROHD 720p sequence, cropping 8 pixels from the top and bottom to eliminate black bars, the rendered file is correct when using either the Export function or the Queue function.
              2. If I export to a DV Widescreen AVI from an AVCHD 720p (1280x720) with DVCPROHD 720p footage in it, cropping 8 pixels from the top and bottom, the Queue version is correct, but the Export version has black pillar bars. It maintains the correct aspect ratio (16:9) in the final file; it's like the export does a center crop, however, and pads black on the sides.
              3. A 1280x720 clip or graphic exported from the Source Window to a DV Widescreen AVI, cropped 8 pixels from the top and bottom, shows the pillar bars in direct export.
              4. A DVCPROHD 720p clip exported from the Source window to a DV Widescreen AVI, cropped 8 pixels, exports correctly
              5. A 1920x1080 clip or graphic exported from the Source Window to a DV Widescreen AVI, cropped 12 pixels from the top and bottom, shows the pillar bars in the direct export.
              6. A 720x480/.9091 clip or graphic exported from the Source Window to a 320x240 H.264 MP4, cropped 8 pixels from the left and right, shows pillar bars in the direct export.

               

              Obviously, there are virtually endless permutations that could be tested, but I think the one thing that is clear is that when hardware MPE is enabled, cropping is not being performed correctly when exporting directly from Premiere. Since Andy has found this on his officially-supported card, I think that indicates an issue with MPE itself; I will file a bug report to this effect.

               

              If anyone else has discovered bizarre cropping issues in their exports, please post here; in the bug report I'll link to this thread to hopefully offer as much evidence as possible to where the bug lies.

              • 4. Re: Battling Hardware MPE, Episode 1: Cropping on Export
                Andy Urtu Level 1

                One minor update.  I was exporting from 35mbit JVC MPG2 footage (This is just like Sony EX1 footage)

                 

                Thanks for filing the bug report.

                • 5. Re: Battling Hardware MPE, Episode 1: Cropping on Export
                  Colin Brougham Level 6

                  Got it. I'm assuming that is square pixel footage, not anamorphic?

                  • 6. Re: Battling Hardware MPE, Episode 1: Cropping on Export
                    Andy Urtu Level 1

                    Yes 1280x720 square pixels.

                    • 7. Re: Battling Hardware MPE, Episode 1: Cropping on Export
                      Ratphink131

                      I just found this thread and would like to find out if the problem has been resolved as we are experiencing the exact same issues. We have 3 stations running CS5 with the recommended Quadro FX4800 cards, two of the cards are up to date on drivers and another is using the last version of drivers, so both drivers experience this. We've also found that this only appears when we are outputting 4:3 video and not 16:9.

                       

                      There is an older thread from June 2010 that mentions it but not answered, this is a more recent one and don't know what the final answer was other than a bug report being sent in.

                       

                      Thanks

                      • 8. Re: Battling Hardware MPE, Episode 1: Cropping on Export
                        Colin Brougham Level 6

                        I haven't had any issue with this since the 5.0.3 update. Are your installs fully updated?