Latest post Fri, Oct 20 2017 4:43 PM by Decorados Cinematográficos Moya. 8 replies.
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  • Fri, Jun 16 2017 7:39 AM

    freme rate conversion 50p to 24p

    anyone knows how to do a proper frame rate conversion from 50p to 24p for dcp?

    i have the avid media composer 8.8.4 symphony option.

    thanks.

  • Fri, Jun 16 2017 11:50 AM In reply to

    Re: freme rate conversion 50p to 24p

    Depends what you mean by proper.

    You can't make 50 fit into 24 it just doesn't go.

    In MC you have 2 tools. One is effectively frame blending. This mixes groups of frames to reduce or increase the output framecount as needed. If the content has little movement this can often look fine. If the image has a lot of smooth movement then you will see ghosting (blending) on some frames.

    Avid fluid motion is a different method or working out how to output the correct framerate by looking at objects in each frame and how and where they are moving and then rebuild each frame. This is very slow even on a pwoerful system and can easily be upset by large content changes.

    Other conversion systems will oftne drop frames to make the numbers work and you will see  a stutter or jump in the content.

    The most established method is to use something like an Alchemist convertor. Which is a dedicated unit designed to do what Avid fluid motion does but in real time and more accuratley.

    If you have to do it in MC then you could use normal motion adapters for the content. tweak each shots settings to get the best result and resort to fluid motion on clips that still have issues.

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  • Sat, Jun 17 2017 6:21 AM In reply to

    Re: freme rate conversion 50p to 24p

    thanks by proper i mean no artifact since i'm preping for cinema release. but the budget is limited.

    like you said. if i load the 50p sequence into a 24p projects and go through all the shots one by one to check if they are ok and tweak the motion adaptor settings. will the result be good enough?

    will the symphony option help in anyway since it has unversal mastering? it's all file based. thanks

  • Sat, Jun 17 2017 4:38 PM In reply to

    • mjolnarn
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    Re: freme rate conversion 50p to 24p

    kingpeng0318:

    like you said. if i load the 50p sequence into a 24p projects and go through all the shots one by one to check if they are ok and tweak the motion adaptor settings. will the result be good enough?

    I would play it out through a DNxIQ letting it do the conversions, capturing , SDI or HDMI , could be done to an external recorder or, if you need a ready encoded publishing file , to a Matrox Monarch , letting that one do the finishing H 264 encode

    kingpeng0318:

    will the symphony option help in anyway since it has unversal mastering? it's all file based. thanks

    You´ll also need the DNxIQ for that from what I´m aware of

    add .. link .. DNxIQ

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  • Thu, Jun 22 2017 5:32 AM In reply to

    Re: freme rate conversion 50p to 24p

    Pat Horridge:

    Depends what you mean by proper.

    You can't make 50 fit into 24 it just doesn't go.

    In MC you have 2 tools. One is effectively frame blending. This mixes groups of frames to reduce or increase the output framecount as needed. If the content has little movement this can often look fine. If the image has a lot of smooth movement then you will see ghosting (blending) on some frames.

    Avid fluid motion is a different method or working out how to output the correct framerate by looking at objects in each frame and how and where they are moving and then rebuild each frame. This is very slow even on a pwoerful system and can easily be upset by large content changes.

    Other conversion systems will oftne drop frames to make the numbers work and you will see  a stutter or jump in the content.

    The most established method is to use something like an Alchemist convertor. Which is a dedicated unit designed to do what Avid fluid motion does but in real time and more accuratley.

    If you have to do it in MC then you could use normal motion adapters for the content. tweak each shots settings to get the best result and resort to fluid motion on clips that still have issues.

    if i convert 50p to 25p first? will that yeld better result?

  • Thu, Jun 22 2017 7:41 AM In reply to

    Re: freme rate conversion 50p to 24p

    kingpeng0318:

    if i convert 50p to 25p first? will that yeld better result?

    Probably not.

    50 to 24 or 25 to 24 just aren't good fits. few frame conversions are.

    So if you need to get 24 frames in a second from a selection of 25 (or 50) the maths just don;t work.

    With blending many famres will be used as they are and a small group will be rrmade to end up one frame short.

    That group of frames will be made up of a mixture of frmaes so will have blending (ghosting) on moving parts.

    Also the timing of flow of movement will have subtle shifts as one part of the second is slightly compressed in time.

    Fluid motion or motion compensation is different as all the output frames are recreated based on the movement of the objects over time.

    I would suspect that 50P would give more information and produce a beter output at 24P But I've not tested it.

    Even going from 50P to 25P isn't easy. If you drop every other frame (the simple way) you will create a shutter effect and see a slight strobing of the image. A 50P clip converted to 25P isn't the same as an original 25P clip.

    So to make 25P from 50P you need to blend 2 frames together to make one new frame.

    ACI Moderator. I'm not employed by Avid or work for them. I just do this in my spare time. Symphony V8.6 / 8.3.1 HP Z400 system [view my complete system specs]

     

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  • Sat, Oct 14 2017 12:35 PM In reply to

    • Mercer
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    Re: freme rate conversion 50p to 24p

    There is no need to 'convert' 50fps to 24fps in Avid for a DCP. You can make DCP in one of two ways from a 50fps source:

    1) Although still outside the official spec for DCI DCPs, 25 and 50fps DCPs can be projected on almost all current systems, just a few that haven't had their firmware update will be unable to. I use DCP-O-Matic (which is free) and it allows for producing a DCP for the newer SMPTE standard (as opposed to Interop) at these frame rates.

    2) Or you can treat your source in the classic 35/16mm film shot at 25fps way: i.e. produce a compliant 24fps DCP with your audio pitch shifted by 4%. Again DCP-O-Matic takes 25/50 fps and creates 24/48fps DCPs frame for frame.

    Here is some more info: http://www.jamesmilnersmyth.com/making-a-24fps-dcp-from-50p-or-25fps-video/

    It is much more important these days to follow DCI compliance in terms of picture raster: better to stick to Flat or Scope 2K/4K, even if that means letterbox/pillarbox.

    As always you need to test output with a compliant DCP player or better still have access to real theatre projection facilities.

  • Sat, Oct 14 2017 1:02 PM In reply to

    Re: freme rate conversion 50p to 24p

    kingpeng0318:
    if i convert 50p to 25p first? will that yeld better result?

    If you drop every other frame (convert to 25p by skipping frames), then slow the 25 down to 24, yes, that should yield proper results.

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  • Fri, Oct 20 2017 4:43 PM In reply to

    Re: freme rate conversion 50p to 24p

    It's is posible, my teacher always says that it's better not to do it.

     

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