The DCP I created is a 24fps SMPTE. The source mov was 23.978. Its been shown fine at at least 1 cinima but got this from another one who said there was a technical problem.
We've just tested the DCP for 'Translations' and found that it has technical issues.
Only 24fps and 25fps are really advisable for cinema use (though 30 and 48 are technically possible).
This DCP is 24, but we are guessing that it was shot/edited at a non-standard frame-rate, and then when transcoded to DCP in DCP-o-matic the frame-rate was changed or rounded to 24fps rather than properly converted at the mastering stage.
The result is that the DCP has motion issues. Style-wise the film is fairly static, but there is still a jerky distracting look to playback.
The DCP is screenable, but not ideal.
Very odd. Any idea what I should do? I guess the editing SW could export 24fps, this may sort out the problem but won't know until the Cinima ingests and tests it which will take a while.
Was shot on video. Think it is a strange 'optical illusion' type thing the projectionist picked up due to slight jerkiness in the camera work. Ive played it 1/2 speed and it seems OK,
OK. It's hard to imagine how DCP-o-matic could cause such problems, unless there's a bug... for 23.976 content it just uses the video frames from the input but runs them slightly fast and fudges the sound to keep it in sync.
Maybe there is a different problem. Datarate, or something. And then it may appear as if it happened with the frame rate adaption. Which is really artefact-free if the source was a real 23.978fps with a steady frame cadence. All DCP-o-matic is doing is taking each 23.978 frame and tell the DCP player to play it at 24fps. Which causes a minute constant acceleration. Nothing that anyone is able to pinpoint, not even in a direct 23.978 <> 24 fps A/B comparison.
I use DCP-o-matic mostly on 23.976 content (our productions, and HD/UHD Blu-ray rips) and never spotted anything troublesome with the resulting visuals. It's kind of annoying that people are always ready to blame DCP-o-matic when something goes wrong, as if there is no other software, hardware, or individual implicated in a film post-production...
I also like the bit about "non-standard frame-rate": the list of standard frame-rates is rather long.
Last edited by Kewl on Sat Jun 17, 2023 8:56 pm, edited 1 time in total.
I always take care in converting a video with a different frame rate than 24 or 25 fps to the most appropriate frame rate (generally 24 if I have to use Interop for the DCP and 25 if I have to use SMPTE), because I believe it is much better for DCP-o-Matic to work on frame rates it is comfortable with.
Some QC labs, especially for some important festivals, tend to be extremely picky -- lately I had to discuss with a festival that found a lack of sync that WAS THERE, but so imperceptible that I basically told them off, politely -- because they are going to show the DCP in a professional theater most of the time and the projectionist might object to this or that.
Therefore, although DOM is a wonderfully crafted tool, if you also have Final Cut Pro or Da Vinci Resolve to create a Print Master, it is much better to walk the extra mile, prepare a master file that is suitable in sound and vision and, thus, avoid a lot of headaches in the process.
Therefore, although DOM is a wonderfully crafted tool, if you also have Final Cut Pro or Da Vinci Resolve to create a Print Master, it is much better to walk the extra mile, prepare a master file that is suitable in sound and vision and, thus, avoid a lot of headaches in the process.
Perhaps you could talk more about the headaches that you find when converting a 23.976 file to 24fps in DCP-o-matic, instead of doing it in Resolve?
If Resolve is somehow doing a better job, it would be nice to know the details of why it is better, so that either we can fix DCP-o-matic, or point out cases where using Resolve is a good idea.
In particular, I'd very much like to know what Resolve is doing differently in this case, other than playing the exact same video frames at a slightly higher rate.
I am sorry, Carl, I didn't mean to say that Resolve is better, and I actually prefer to use Final Cut Pro, because it is far easier to use than Resolve.
I mentioned Resolve because it has the same features and it is free of charge unless you want to use more professional features, while Final Cut Pro is only available for a fee and perhaps not everyone wants to pay money for an app that has a free alternative.
I am just saying that in my lab activity, having to deal with producers and directors who make films at different frame rates and never provide a full 5.1 mix but audio stems, or with Festivals, which are very particular when it comes to DCP outputs, I want to make print masters that follow specific standards and that I can check before importing them into DOM.
First, with my computer setup, it is already very difficult to play a 120-130 GB Prores file that I import into DOM, because DOM requires a great deal of my computing resources. Final Cut Pro or Da Vinci Resolve do not have that problem with my current configuration. Of course, I could buy a more powerful computer, but money is currently tight in this part of the world, thanks to a pandemic and a war that made prices soar, even for computers.
Second, when you convert 24 fps to 25 or 25 fps to 24 (or any other frame rate into 25 or 24 fps), you have to take care of the sound pitch that ideally should sound the same as in the original. I tried to import a Prores file as is into DOM and I did not like the way the sound was treated from a pitch standpoint, and I was sure that both the producer and the director would be mad at me for that -- believe me, directors in particular are extremely proud of their work and cannot stand the slightest change, even when they do not know anything about frame rates or sound pitch changes. Final Cut Pro has a great way to treat pitch when you change the frame rate, it has an algorithm that keeps the same pitch even when speeding up or slowing down the film.
With a previous version of DOM, I even experienced a loss of sync. I do not know whether that was fixed with subsequent versions, but as I said, I do not import Prores files into DOM without preparing a print master first.
Third, I tried a couple of times to import stereo tracks into DOM and make pseudo 5.1 tracks, but I did not have a theater at hand to check the results, while in Final Cut Pro I can produce pseudo 5.1 tracks for the Print Master that I can check within the software, thanks to the audio level bars, and then import the final result into DOM. If I have 5.1 stems, it is my personal choice to import them into Final Cut Pro (we are talking about 18 tracks), make a good 5.1 mix and import the final result into DOM. Being partially deaf, visuals are very important for me and checking sound levels with graphic aids is extremely important.
But again, I am not saying that Final Cut Pro or Da Vinci Resolve are better than DOM, I was just telling my experience working with films, without being judgmental. I am sorry if I sounded otherwise.
In fact, DCP-o-Matic is my only choice to make DCPs. And it does an excellent job if you load a good Print Master into it.