6 Replies Latest reply on Aug 8, 2011 12:01 AM by mmdeziner

    Why is 24 fps getting converted to 23.98 at export?

    mmdeziner Level 1

      I am editing a short shot on RED. My source footage is at 24 fps. My sequences settings are also 24 fps. When I am exporting to Quicktime, the output turns to 23.98 fps even though I select NTSC DV 24P. Whether I choose DPX or Quicktime, the output changes to 23.98. Why is it so?

       

      If I check the box match sequence settings then it does it at 24 fps but the format changes to MPEG Preview.

       

      How do I make sure when I select export at 24 fps for any format, it actually does export at 24 fps.

       

      Thanks.

      RV

        • 1. Re: Why is 24 fps getting converted to 23.98 at export?
          Jim_Simon Level 8

          You'll need to choose an export format that allows true 24 fps.  Not all will (such as DV).

          • 2. Re: Why is 24 fps getting converted to 23.98 at export?
            mmdeziner Level 1

            Thanks Jim. So which format would support true 24 fps export? Even DPX format is making the output to 23.98.

             

            RV

            • 3. Re: Why is 24 fps getting converted to 23.98 at export?
              Colin Brougham Level 6

              The thing to be aware of is that when selecting a preset for a given format (which is what it sounds like you're doing) is that all of the encoding parameters will be set as dictated by the preset, and not by your input source, whether it's a clip or a sequence. The presets have no knowledge of the source's parameters, so just think of them as rough "recipes" that you can vamp off of.

               

              In that case, once you've selected the format that you want to use for export (e.g. DPX), select the preset that most closely resembles the output you want, and then tweak the parameters. Looking at the DPX presets, all of those that are labeled "24p" use an actual framerate of 23.98, which is pretty common for video cameras. Digital cinema cameras, like the RED, also shoot at true 24p (that is, 24.00), but why there aren't prerolled presets for this framerate, especially in the DPX format, is a little strange. It's not a big deal: just change the framerate (and any other parameters you want) and then save your own preset so you can quickly apply it next time.

               

              Other formats, like QuickTime, are capable of using a variety of different codecs, some of which have very specific (read: limited) encoding parameters. When you select a preset for one of these formats, you're also specifying a particular codec, so you might be constrained from exporting to the exact file you're looking for. Ultimately, there is a format and a codec for every purpose, so it really depends on what your intended destination is. Except for a few options, you should almost always be able to get the output you need. The key is to not rely on the built-in presets as the end all, be all for your encoding choices. Use them as starting points, and then tweak to your heart's content. If you need advice on a specific format, feel free to ask!

              • 4. Re: Why is 24 fps getting converted to 23.98 at export?
                mmdeziner Level 1

                Thanks Colin for the detailed reply - it's very helpful. You are right, I am selecting a preset. However I am unable to tweak the fps parameter (it's grayed out) for both Quicktime and DPX export. I need to export this footage in DPX and Quicktime at 24 fps - if you can help with that, it will be great.

                 

                RV

                • 5. Re: Why is 24 fps getting converted to 23.98 at export?
                  Colin Brougham Level 6

                  DPX should not be locking you into a specific frame rate; it's an image sequence (so long as the Export as Sequence box is checked), so you've got lots of flexibility regarding the output frame rate. Can you show a screenshot of the DPX frame rate being unselectable/unchangeable?

                   

                  QuickTime is a different story, since it's just a container format. Once you select QuickTime on the Format dropdown, you'll have to go to the Video tab and pick the codec you want to use. With QuickTime, you have a couple dozen choices built-in, plus any additional QuickTime codecs you've installed, e.g. Avid DNxHD. If you've selected, say, the DV NTSC preset, that will select the DV codec--and that has very limited frame rate possibilities. That's a function of the codec. If you change the codec to something like Animation or H.264, you'll have many more frame rates and frame sizes you can pick from. QuickTime can be used for lots of different deliverables--everything from uncompressed MOVs for further editing/compositing to highly compressed versions for devices like iPhones. That's why you have to be specific about your delivery requirements, instead of just saying "I need a QuickTime." Once we know that, further recommendations can be made.

                   

                  Do look again at the DPX settings, and if it is indeed an issue where you can't change the parameters, post a screenshot of the export settings window.

                  • 6. Re: Why is 24 fps getting converted to 23.98 at export?
                    mmdeziner Level 1

                    Hi Colin,

                     

                    Checking the box "Export as Sequence" allowed me to tweak the fps rate. Quicktime is needed in a format that can be opend in ProTools - tried h264 and it worked. Thanks.

                    RV