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Activity Forums Adobe Premiere Pro Multiple Frame Rates causing entire project to lag (PP v23.6)

  • Multiple Frame Rates causing entire project to lag (PP v23.6)

    Posted by Paul Boshoff on September 5, 2023 at 8:24 am

    Hi everyone

    I am in need of help. I’m editing a project containing multiple frame rates, most notably 25fps and 50fps. For editing all the media is assuming it’s native (25 and 50fps) so as to playback and normal speed. What is strange to me is that it is only specific scene in the project that is causing a problem. When I scroll and work through the rest of the sequence things go smooth a gain, but as soon as I reach the scenes in question, everything starts to lag. Even the basic operating of Premiere Pro itself. The media in these scenes don’t seem any different from that in the other. All media was shot on a Fuji and is in the following format:

    The 25fps:

    Type: MPEG Movie
    File Size: 4,94 GB
    Image Size: 1920 x 1080
    Frame Rate: 25,00
    Source Audio Format: 48000 Hz – 24-bit – Stereo
    Project Audio Format: 48000 Hz – 32 bit floating point – Stereo
    Total Duration: 00:16:40:00
    Pixel Aspect Ratio: 1,0
    Alpha: None
    Color Space: Rec. 601 (NTSC)
    Color Space Override: Off
    Input LUT: None
    Video Codec Type: MP4/MOV H.264 4:2:0 (Full Range)

    And the 50fps:

    Type: MPEG Movie
    File Size: 275,79 MB
    Image Size: 1920 x 1080
    Frame Rate: 50,00
    Source Audio Format: 48000 Hz – Compressed – Stereo
    Project Audio Format: 48000 Hz – 32 bit floating point – Stereo
    Total Duration: 00:00:23:00
    Pixel Aspect Ratio: 1,0
    Alpha: None
    Color Space: Rec. 709
    Color Space Override: Off
    Input LUT: None
    Video Codec Type: MP4/MOV H.264 4:2:0

    I’ve tried editing in a 25fps sequence as well as a 50fps sequence and the problem persists.
    I’ve made proxies of all the footage and this also doesn’t help.
    I’ve created a new project and imported the sequences into it and this hasn’t helped.

    I’ve made low resolution 25fps renders of the 50fps media and still, nothing.

    If anyone knows anything that might help, please reach out.



    Paul Boshoff replied 10 months, 2 weeks ago 2 Members · 5 Replies
  • 5 Replies
  • Paul Boshoff

    September 5, 2023 at 11:18 am

    An additional thing I’ve noticed is that some of the clips don’t show through edits while others do. Sometimes it is a 50fps clip, other times a 25fps clip so if there is a pattern here, I can’t see it.

  • Mads Nybo jørgensen

    September 6, 2023 at 12:18 am

    Hey Paul,

    Loads of info, great.
    Thank you for sharing.
    Only thing that additional info that might be helpful is as to where the footage is originating from?
    (Camera, Zoom, or other source)
    Also, was the 50 fps shot for slow-motion?

    A few observations:

    One thing that stands out on the 25 fps footage is:
    Color Space: Rec. 601 (NTSC)
    Maybe match that to the 50 fps footage:
    Color Space: Rec. 709
    Also check as to why the 25 fps thinks that it is operating in a NTSC color space?
    (Not sure that it matters whether it is NTSC or PAL – but it could do)

    You could as a test on the 50 fps footage try “modify it” to 25 fps?
    So both sources are the same frame-rate – again, should not make a difference, but…
    Basic instructions here for changing frame-rate (just in case):

    The duration on the 50 fps file does not look right:
    Total Duration: 00:00:23:00
    As in from your description, it suggests that this clip should be much longer than 23 seconds?
    If so, it may be that the MP4 file is corrupt.
    Might be worth putting the 50 fps clip through media-encoder, and at the same time change it to a 25 fps clip.

    Hope that this helps.
    There are smarter people hanging out in the barn, who may have additional suggestions.


  • Paul Boshoff

    September 6, 2023 at 8:05 am

    Hi Mads

    Thanks for taking the time to help out.

    The footage came from camera. Specifically three Fuji Cameras (Xh2, Xh1 and a xt4).

Excuse me if my response comes across as too detailed, but I’d rather give too much information than too little.

I don’t believe the 50fps footage was shot in slow motion no. They all have sound with them, however, when I interpret the 50fps footage to assume a 25fps frame rate it does play back in slow motion, I then speed the clips up to 200% to compensate, but doesn’t seem to help the problem.

I have modified all the clips to match that of the sequence (Rec.706 not Rec.709 (NTSC)) but sadly this has also not yielded any results.

    The clip duration you bring up was my mistake. I posted the properties of the 50fps clip from the timeline instead of the source code so it was the duration of the clip used, not the entire clip. I’ve checked though, and that is the only difference between the properties from the clip in the timeline and the project media bin.

    Would it be possible for the project to have gotten slower and slower over time as a result of copying and editing footage from and between different fps sequences into the main sequence?
    And if so, would there be any issues if I edited the whole thing in 50fps sequences only but did a final export as 25fps? I ask as the original project file I received from the client containing all the raw footage sorted into sequences for each scene were all 50fps sequences (even though containing 25 and 50fps footage) and seemed to run smoothly. But the deeper I got into the editing process, the slower the scene in question made the project.

    Final thought is that I’ve looked at all the sequences settings and the one with the problem had a different “Fields” selected. The ones without issues are set to “No Fields (Progressive Scan)” while the problematic one was set to “Upper Field First”. This didn’t make much of a difference either. A question on this (seems silly but need to make sure), if I edit in a “Progressive Scan” sequence and export as “Upper First”, could it cause any problems with the final export? The channel I’m delivering to insists on “Upper First”.

    Thanks again for your time and advice, but it seems the search continues.



  • Mads Nybo jørgensen

    September 6, 2023 at 10:25 am

    Hey Paul,

    Don’t worry, detail, although slightly time consuming 😉 is very good.
    The joys of taking over a 3-camera project shot on 3 different camera models…

    It sound like the key to your solution is to have the end in mind.
    As in if you have delivery specs from client, then that is where you should start.
    For now I would assume that you are going to deliver 1920 x 1080 HD.
    But is it for Broadcast (terrestrial), streaming (YouTube?) or screen projection playback, or similar?

    Based on the size of the file, your 50 fps second file at at 275,79 MB (v 4,94 GB for the 25 fps) suggests that there is a lot of compression going on, whilst 50 fps would add even more uncertainty as to where the full frames “land” in playback. (This is again depending on length of the clip – if a shorter 50 fps clip, then the compression could be the same)

    “Would it be possible for the project to have gotten slower and slower
    over time as a result of copying and editing footage from and between
    different fps sequences into the main sequence?”

    In theory yes – but this where it comes down to the specs of your system and drives (HDD / SSD – on USB / Thunderbolt / Raid and so forth)
    One way of dealing with it, could be to edit each part (section) in different projects, and stitch them together in the end.

    “the one with the problem had a different “Fields” selected”

    Could be the problem, but that is assuming that all three cameras are recording in the same codec, in which case it is worth matching them up.

    “The ones without issues are set to “No Fields (Progressive Scan)””

    The whole “Fields” discussion is a red herring, as if you are shooting progressive, there are NO fields (although some codecs, potentially like a 50 fps recorded file, might “stuff” 2 full frames into one and call it fields – other smarter people here can elaborate on this).

    Don’t know how far you are in the editing process, but I would consider re-encoding the 50 fps footage to a 25 fps file, like ProRes or similar – then that problem might be erased with very little, if any, degradation to the source footage.

    “The channel I’m delivering to insists on “Upper First”.”

    As your client has already shot in progressive, then that footage will always apppear as progressive in playback regardless of how the final master is exported.

    If channel says “Upper First” I would check if they are more specific about the codec that they want you to deliver in.
    There is nothing wrong in editing your camera source footage in progressive, and add vfx, title sequence, graphics, end roll and so forth in “interlaced” and export is it as interlaced master – your video footage will always remain progressive regardless of the final output.

    You could edit the video, export the edit as a flat ProRes file, and then add all of the graphics etc on top of that in a PPro Sequence set to interlaced (1080i instead of 1080p), before doing a final pass for the end-client master.

    I should add that some of my suggestions above, again depending on where the film is to be used, is possibly not a good idea to suggest in public…
    (In a distant past I have worked on DV-Cam PAL footage mixed into a HD project, that was transferred to 35mm, and projected in ta large audience in a big cinema – difficult decisions had to be made to make that happen…)

    Hope this helps.


  • Paul Boshoff

    September 7, 2023 at 7:33 am

    Hi Mads

    You Assume correct yes. My final delivery to the client is for broadcast and the specs need to be:

    1920×1080 HD
    Codec: XDCAM 50 4:2:2
    Bit Rate: 50
    Wrapper: MXF
    Frame Rate: 25

    Which I have been exporting a range of other projects to them over the years so at least I know that part of the workflow works fine.

    Your note on my system specs was my first fear too, but I’m working on a few other projects with heavier RAW footage which indicates that shouldn’t be the problem. Not to mention that the problem only starts when I have the two troublesome scenes open in the timeline view. So that is somewhat of a relief (no expensive upgrades needed just yet.)

    I like your suggestion of editing these scenes in separate timelines to at least allow me to edit the rest without the problem.

    Thank you for clarifying the whole “fields” situation. I’m not going to bend my head about it as it was shot as Progressive and like you suggest, there are workarounds that will do just fine come final export.

    One more thing I learned recently (never too late to learn) is to change “Preview File Format” in the Sequence Settings from Quicktime to I-Frame Only MPEG to help ease the load of playing back a variety of different file types.

    I’ve wrestled through the first episode and all its troubles for now and am starting with the second today. I’ve set up the project afresh with all of your insights and the rest I’ve mentioned and will see how it goes. There are four episodes in total, so though I hope everything goes fine from E02, I’m sure by E04 I will have it figured out. If not, I will come back here and knock on your door again.

    Thanks again for all your help.

    Warm regards

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