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mindopera

23.98 frame rates and playback in WO

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I'm trying to understand the reasoning behind framerate choices, mostly because I receive so many different ones such as 30, 29.97, 25 and the one that is the most perplexing, 23.98.  I know WO can play this different frame rates and filmmakers like the idea that they are matching the frame rate and stutter of old-school film (celluloid) and they will get the same look if played back at 23.98

 

  1. Is it better to film at 23.98 and output playback files (HAP-Q) for WO at 30fps?  
  2. Is there any real advantage to achieving a film look or is this a myth handed around?
  3. Will there be any sync issues if 23.98 fps is changed to 30 fps and played back with a separated audio file and looped over a long time in WO?
  4. What has been your experience, thoughts, and solutions for the framerate question?

Thanks

 

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I don't know that i can answer about "real advantage", although I know our editors want to work in 23.98 (since that is what they shoot the original footage at).  My experience is that using native 23.98 in WO can result in stutters during playback as WO needs to do a real time conversion to 30fps.  The best results I have achieved are to do a render of the final file to 30fps before bringing it in to WO.  Since I need to do a render for the HAP file anyway, it doesn't add an extra step to the process.

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No, the upsampling will be to the framerate actually used by WATCHOUT, which is often 60 fps (not 30). If the source is 24, there will always be a discrepancy when upsampling to something that isn't an even multiple. Frame blending, and similar techniques, can be used to improve this (whether done in WATCHOUT or ahead-of-time in, e.g., After Effects). But upsampling to 30 or 60 from 24 is also going to give you larger/heavier files - especially whe using codecs such as HAP, which may negate some of the advantage of upsample ahead of time.

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On 2/26/2018 at 4:30 AM, mindopera said:

I'm trying to understand the reasoning behind framerate choices, mostly because I receive so many different ones such as 30, 29.97, 25 and the one that is the most perplexing, 23.98.  I know WO can play this different frame rates and filmmakers like the idea that they are matching the frame rate and stutter of old-school film (celluloid) and they will get the same look if played back at 23.98

 

  1. Is it better to film at 23.98 and output playback files (HAP-Q) for WO at 30fps?  
  2. Is there any real advantage to achieving a film look or is this a myth handed around?
  3. Will there be any sync issues if 23.98 fps is changed to 30 fps and played back with a separated audio file and looped over a long time in WO?
  4. What has been your experience, thoughts, and solutions for the framerate question?

Thanks

 

Hello,

This thread might be old but I am exactly on the same boat.  With most of my shows being conferences, clients and speakers would pass me last minute video files which are most of the time 25 fps and 29.97fps.  5 years ago i've done heavy testing and comparison of different file format/containers and frame rates.  at that time, mpeg @60fps rendered 16mbps Constant bitrate was my optimum setting.  No stutters or lags on a span of 10 projector setup.  Now with HAP-Q introduced and H264 mp4 playback being stable.  Is this still an important pre-requisite?  At the moment, I always ask my clients to provide files in 30fps.  Is watchout now capable of playing any framerate with no stutter/lag?  especially if 2 video files are being played at the same cue but with different framerate.

 

Will ofcourse do another test for this but I am curios to know your experience with this.  TIA

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Stutter may come from many sources, for example:

  • Inadaquate hardware to play the content (either in isolation or along with other content).
  • Mismatch in framerate (e.g., 25 fps in; 60 fps out).

The first point can only be fixed by having adequate hardware for the content at hand. The second point seems to be most of what you're concerned with here. Historically, this has always been a concern in WATCHOUT. And having a source framerate that's an even multiple of the output (graphics card) framerate is always advantageous. For example, if WATCHOUT outputs 60fps, using video that plays at 60 or 30 fps is optimal. If you play 25fps video in this case, there will always be some "temporal aliasing" going on, that can be seen as stutter. 

The introduction of frame blending in WATCHOUT alleviates this to some extent, by blending adjacent source video frames together when framerates don't match, to make the resulting video framerate match the output rate. This often results in smoother perceived playback, but may also introduce some blurriness due to the frame blending itself.

Finally, I would see no real benefit in upsampling 30fps to 60fps when making the video files (regardless of codec). If the source material is 30fps, you won't really gain anything by outputting two identical frames (at 60fps) for every input frame. You're really just wasting resources by having to play back twice the amount of data without any advantage. If there's some processing, though (such as After Effects vector-based frame blending), that may in some cases result in a smoother playback, since you then synthesize those missing in-between frames. For some content, this may result in dramatic improvements in smoothness, while for other content it results in strange artifacts that just make thing look worse. 

Of course, the smoothest results will be achieved when playing back content shot at 60p with an output rate of 60fps (or 50p on 50fps if you're in PAL land).

Mike - http://pixilab.se/

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