12 Replies Latest reply on Sep 26, 2011 1:17 PM by Bucketheadd

    Conform, or Transcode Mixed Frame Rates?

    OstiaAlex Level 1

      Hi,

       

      I've done a quick search through the archives, but still can't quite get my head around this:

       

      I recently shot a personal project on a Greek Island. I have a lot of beautiful 5D MKII footage of the island at 1080/25p, some underwater footage that the dive instructors took at 1080/30p and a ton of GoPro HD helmet cam stuff that I shot from my motorcycle at 720/60p. I guess I didn't think too much about the mixed frame rates while shooting, as I was having too much fun. I wanted to shoot the helmet cam stuff at 60p so I could slow it down and have some nice ride-by shots to mix with my GVs. Now that I'm in front of the edit suite, what is the best way to utilize all of this footage? I will use 1080/25p as my time base because the majority of the good stuff was from the 5D. I've heard that using Twixtor to conform footage works really well, but I'm even confused as to what the 60p stuff will look like on the 25p timeline. Will it play slow? Very confused.

        • 1. Re: Conform, or Transcode Mixed Frame Rates?
          Colin Brougham Level 6

          In general, it's "better" to drop lower frame rate materials into sequences with higher frame rates. The reason is that Premiere Pro will automatically insert pulldown in the form of duplicated frames to maintain the same frame cadence. Let's look at some examples using the footage you mentioned...

           

          You've got 1080/25p, 1080/30p, and 720/60p. Let's ignore the frame sizes, and since you're all progressive, let's ignore the field order (since there is no field order). In short, you got 25fps, 30fps, and 60fps. The first thing to do is decide what you're going to do with the 60fps material. If you want to slow it down, simply interpret it as 25fps or 30fps; right-click a clip or multiple clips, and select Modify > Interpret Footage. There, you can change the frame rate. This will cause the footage to playback at at least 50% of the speed; you'd then use it in a sequence with a timebase matching whatever you interpreted the footage as (25p or 30p). If you want to keep the footage at 60p, so that you could use some full-motion clips and then have the option to slow some down, you'd use a 60p sequence; you then can use the Speed/Duration dialog to change the speed of the clip. If you want 50% speed, punch that into the dialog without any worry of interpolated frames; Premiere Pro will simply double each frame, giving you nice, smooth slow motion.

           

          Now to decide on the 25fps and 30fps material, and how to use that. If you use a 60fps sequence, you can just drop these clips in as-is; Premiere Pro will duplicate frames as necessary, maintaining the same cadence as if you used the clips in a sequence with a matching frame rate. It's pretty simple, really: it doesn't matter whether you shoot at 25fps or 60fps, because one second is always one second. All that's different is the duration for which a frame is visible. If you have 25 frames to fit into 60 frame "slots" in your sequence, Premiere Pro will space out the frames roughly evenly, and duplicate each frame as necessary to approximate the duration of a single frame in a sequence that matched the clip's frame rate. Visually, there is no difference--that's why it's better to go to a higher frame rate than lower. If you go lower, Premiere Pro will actually skip frames because you have more frames to fit into those "slots" in the destination sequence. This will result in a perceived "jump" where a frame is skipped. You can mitigate this, somewhat, by right-clicking a clip in a sequence and turning on Frame Blending; this forces Premiere Pro to interpolate between skipped frames. It may work OK for you, or it might appear to blurry--testing is the best way to determine.

           

          Personally, I think I'd go with a 720/30p sequence, assuming that all of the motorcycle 60p footage will be slowed down. The 1080/30p footage will simply have to be scaled down; the 1080/25p footage also only needs to be scaled, since every fifth frame will be duplicated to match the 30p sequence frame rate; and if the 720/60p is interpreted as 30p, you'll get some nice 50% slow-motion in your sequence, with no scaling required.

           

          Still confused?

          • 2. Re: Conform, or Transcode Mixed Frame Rates?
            OstiaAlex Level 1

            Great! Thanks again Colin.

             

            I think I'll go with a 720/60p timebase as I will definitely want to use parts of the GoPro stuff in full motion. Got lots of nice 1st person footage of twisty mountain highways etc... I'll drop the 30p and 25p stuff onto that timeline as you suggest and see how it goes. Just out of curiosity; what happens to the sound in all of this?

            • 3. Re: Conform, or Transcode Mixed Frame Rates?
              Colin Brougham Level 6

              I'll drop the 30p and 25p stuff onto that timeline as you suggest and see how it goes.

               

              Sounds good. You're probably going the simplest route, as you don't have to do anything with the footage, beyond changing the size--and you can even set the Default Scale to Frame Size preference to account for that, if you like, to make it even easier. Here's some more information on that topic: Scale assets automatically (automatic) or Scale assets to frame size (manual).

               

              Just out of curiosity; what happens to the sound in all of this?

               

              You shouldn't have to worry about that. I'm guess that most of your footage's audio is at 48kHz, and that's the default sample rate for most sequence in PPro anyway, so it'll be just fine. There won't be any speed or pitch shifts, if that's the concern.

               

              Kinda nice when you get to just edit without thinking about this stuff, eh?

              1 person found this helpful
              • 4. Re: Conform, or Transcode Mixed Frame Rates?
                OstiaAlex Level 1

                Perfect. I'll give this a try and will now start a brand new project with all files transcoded to their native size/frame rates in ProRes.

                 

                Your last question/statement ended with 'eh?' which means that either you're Canadian, or it proves that Canadians aren't the only one's to use eh.

                 

                eh.

                • 5. Re: Conform, or Transcode Mixed Frame Rates?
                  Colin Brougham Level 6
                  Perfect. I'll give this a try and will now start a brand new project with all files transcoded to their native size/frame rates in ProRes.

                   

                  One thing of note is that you don't need to transcode any of these files; I use Canon DSLR clips and GoPro clips frequently, straight from the camera. Plop them into your project and go to town. ProRes is fine if you're finding the native clips too much for your computer to handle, but strictly speaking, you can eliminate the transcoding step completely.

                   

                  either you're Canadian, or it proves that Canadians aren't the only one's to use eh.

                   

                  eh.

                   

                  Ha! Close, but not quite. Just a Michigander... or Michiganian... depending on who you talk to

                  • 6. Re: Conform, or Transcode Mixed Frame Rates?
                    OstiaAlex Level 1

                    Hey Colin,

                     

                    You've been very helpful since I've joined this forum. Maybe you can offer some suggestions for this 'little' problem I've been having with PPro 5.5

                     

                    Since I've been running this software I've had about 4 major crashes. The first three were when I was trying to sync sound with native h.264 files. Maybe I was taxing my CPU too much, but after the crash the software displayed a message that basically said the backup project files may be corrupt. When I opened backups of my project they were prone to crash right away. More recently I started a project with mixed framerates as we've been discussing in this thread. I worked for about 2.5hrs on it and used native GoPro footage at 720/60p as my timebase with ProRes 422 25p footage to compliment the GoPro stuff. I had a lot of it layed down on top of a .wav file and was having fun until its started crashing again. I'm going to attach a screen shot of what the crash looked like. I had to force quit PPro and re-load several times. I decided to transcode all my files to make it easier on the system and less prone to crashing. When I went to open that project titled Naxos this morning it had completely dissapeard. No trace of it in 'recently opened', or anywhere else. I did make sure to save it often throughout the project in case it crashed again. Now its in the ether.

                     

                    So.... I've paid lots of money (and I'm past 30 days) for PPro which I really want to love and embrace as my new NLE, but what if I was working on a major project, not just a test one and it vanished into the ether as my others have done? At this point I can't imagine trusting this software with anything that i'm actually going to need.

                     

                    Help!!

                    • 7. Re: Conform, or Transcode Mixed Frame Rates?
                      Colin Brougham Level 6

                      So, are you saying that your project file is nowhere to be found? Or just that the Recent Projects dialog doesn't show it?

                       

                      As far as the crash goes, if it's something very repeatable, it's definitely worthy of a bug report: Adobe Feature Request/Bug Report Form. If it's something specific to the Mac version, I might not be much help since I'm using a PC. It may be helpful to start a fresh thread with those specific issues and crash reports, so that others will be more likely to look at the thread. We'll try to get to the bottom of it, though!

                      • 8. Re: Conform, or Transcode Mixed Frame Rates?
                        OstiaAlex Level 1

                        Hi Colin,

                         

                        That's right, the project is nowhere to be found. I've searched all my hard drives for any PPro project file and its not turned up any versions of this project.

                         

                        Thanks for pointing me in the right direction, but I'm afraid my need to get to work and make up lost time will cause me to go back to what I know in FCP which has never crashed on me. Time is money and so far PPro is costing me both. Might take a break from it and try and come back later to get help.

                         

                        Many thanks for your ultra-quick and helpful responses.

                         

                        -Alex

                        • 9. Re: Conform, or Transcode Mixed Frame Rates?
                          Colin Brougham Level 6

                          I can't fault you for using what works and/or doesn't crash, but without details, no one here can help. Obviously, you've found a bug of one sort or another, since it's a safe assumption that ANY crash is bad. And I totally sympathize with the loss of time, etc.

                           

                          PPro itself should never make a project disappear--I can't even imagine how that would happen--and in the 5+ years I've used PPro (which I've crashed frequently, myself), I've never lost a project. I'm at a loss as to what the cause may be, unless PPro crashing triggered some widespread, catastrophic, OS level event. I'm not saying that PPro isn't at fault for that, but I've just never experienced anything like that, so I can't explain it.

                          • 10. Re: Conform, or Transcode Mixed Frame Rates?
                            OstiaAlex Level 1

                            Thanks again for taking the time. I've just started a new project and it's crashed again. Its hard to say why its happening, as it will just crash (this time after playing on the timeline and attempting to press pause on the spacebar, the .wav kept playing the music and everything else froze) and the spinning beachball will just stay on forever unless I force quit the application at which point there's no dialogue for auto-crash report.

                             

                            Anyway, I'll post any other crash related stuff to a new thread where I we might narrow it down to OS related issues. Who knows.

                             

                            Sincerely thanking you for all your help so far.

                            • 11. Re: Conform, or Transcode Mixed Frame Rates?
                              Colin Brougham Level 6

                              Your preferences might have gotten borked; try holding (I think) Cmd+Opt+Shift while you launch the application. That will force the preferences to be reset, meaning you'll need to recustomize the interface, but may get you back to a point of relative stability.

                              • 12. Re: Conform, or Transcode Mixed Frame Rates?
                                Bucketheadd Level 1

                                Excellent stuff to know! Thanks for all the info here guys! Party on