Exporting to ProRes (packaging?) and frame-rate accuracy.

Anything and everything to do with DCP-o-matic.
IoannisSyrogiannis
Posts: 17
Joined: Mon Nov 13, 2017 8:40 pm

Exporting to ProRes (packaging?) and frame-rate accuracy.

Post by IoannisSyrogiannis » Tue Nov 05, 2019 3:22 pm

I tried to find a similar thread, but I didn't. So, if I may, I would like to ask for collective help.
I exported a few DCPs to ProRes from the "export" feature.
When I import them to Adobe Premiere Pro, the frame rate turns to "24.01" and the frames appear to be more than the DCP.
Here is an example:

DCP-o-Matic
02;11;44.20
189716 frames

Premiere
2,11,44.24(?)
189767 frames

When I try to export an .mp4 file, and import it to Premiere Pro, I get the expected numbers.

Image

The issue was present with the previous (2.14.x) version of DCP-o-Matic and with the 2.15.23 one, from last time I updated.
I contacted a friend about that, with a newer version of Adobe Premiere Pro, and the same happened to him with a trailer.
When he tried to export the same DCP trailer with a propriety DCP authoring program to ProRes, he got from that file 24 fps on the Premiere Pro as a result.

Have anyone had that issue?
How did you got past it?

My first guess was that the issue is just on packaging or metadata. Yet, when I saw that 51 frames' difference there, I thought it might be something else. And when the mp4 file was turning correct, that got me puzzled even more.

I would love some feedback.

Carsten
Posts: 1466
Joined: Tue Apr 15, 2014 9:11 pm
Location: Germany

Re: Exporting to ProRes (packaging?) and frame-rate accuracy.

Post by Carsten » Tue Nov 05, 2019 5:48 pm

My first test would be to create a DCP with an upcounting counter. I did a simple MP4 counting up with frame accuracy as a source a while a go for similar tests. Then export the DCP to ProRes and MP4 and see what comes out.

- Carsten

IoannisSyrogiannis
Posts: 17
Joined: Mon Nov 13, 2017 8:40 pm

Re: Exporting to ProRes (packaging?) and frame-rate accuracy.

Post by IoannisSyrogiannis » Tue Nov 05, 2019 6:35 pm

The thing is that I observe the issue in Premiere, the import of the ProRes back to DCP-o-Matic doesn't show anything out of the ordinary.
So, given the fact that the ratio of the extra frames here is one every (roughly) 3720, I don't expect artifacts like interleaved frames as much as, some kind of time-code glitch, coming from packaging of the frames.

What I am curious about, firstly, though, is if it is just me and my friend experiencing that anomaly or if anyone else here stumbled upon it.
Did anyone else try to import ProRes exports of DCP-o-Matic to Premiere Pro?
Did they have the same results, or everything worked fine for them?

Carsten
Posts: 1466
Joined: Tue Apr 15, 2014 9:11 pm
Location: Germany

Re: Exporting to ProRes (packaging?) and frame-rate accuracy.

Post by Carsten » Tue Nov 05, 2019 6:43 pm

My first try would be to open that Prores File in Quicktime Player. I do have Premiere on my Laptop, but, usually, as far as I know, if you import, Premiere will already do some kind of interpretation based on the current timeline settings (e.g. from 24 to 23.98). Why it wouldn't do that for MP4 then, I have no idea. But I would open both files in QT Player and have a look at video/track properties.

- Carsten

Carsten
Posts: 1466
Joined: Tue Apr 15, 2014 9:11 pm
Location: Germany

Re: Exporting to ProRes (packaging?) and frame-rate accuracy.

Post by Carsten » Tue Nov 05, 2019 10:54 pm

Hmm. Must be a Premiere thingy. I just exported a commercial trailer to both ProRes and MP4. The resulting files are reported with same number of frames (2197 frames for DCP, Prores and MP4). Quicktime Player reports them as 24 fps.

I used DCP-o-matic 2.14.11 stable on a Mac.

Do you know Media Info? Would be interesting to see what this tool reports for your files.

- Carsten

IoannisSyrogiannis
Posts: 17
Joined: Mon Nov 13, 2017 8:40 pm

Re: Exporting to ProRes (packaging?) and frame-rate accuracy.

Post by IoannisSyrogiannis » Wed Nov 06, 2019 8:39 am

The MediaInfo program is reporting the file(s) on Frame Rate Mode as Variable. It states 24.000 fps but it has minimum and maximum also, giving a 0.004 tolerance and doesn't report number of total frames.

Code: Select all

Frame rate mode                          : Variable
Frame rate                               : 24.000 FPS
Minimum frame rate                       : 23.994 FPS
Maximum frame rate                       : 24.006 FPS
The movie inspector of QuickTime (on a windows PC, I haven't it tried on my Mac) also doesn't report number of frames and does report 24 fps.
VLC doesn't report frame rate. At least not reliably.

O.K. I can see that it is probably a Premiere Pro thingy, as you mention Carsten. Yet, it seems to be in correlation with DCP-o-matic. Or, to be more precise, with the codec or codec parameters DCP-o-matic uses (FFMPEG).
That is the reason I am asking in this forum for other people's experience.

carl
Site Admin
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Joined: Thu Nov 14, 2013 2:53 pm

Re: Exporting to ProRes (packaging?) and frame-rate accuracy.

Post by carl » Wed Nov 06, 2019 12:36 pm

You may be seeing stuff related to this bug report which I just belatedly added from my email.

Carsten
Posts: 1466
Joined: Tue Apr 15, 2014 9:11 pm
Location: Germany

Re: Exporting to ProRes (packaging?) and frame-rate accuracy.

Post by Carsten » Wed Nov 06, 2019 1:17 pm

I have seen that 'variable' frame rate thing before where the indicated frame rate is slightly off, but not in DCP-o-matic so far. But I don't export too often.

Wondering wether it could be something with non-aligned audio/video in the trailer? A DCP contains a distinct number of frames. However, what happens if audio is not perfectly aligned with the image?

The trailers I have here obviously do not trigger that behaviour.

Wondering what happens if you import just the MXF file of a DCP and export that (video only for now).

I would try to find a trailer that provokes the issue, and one that doesn't, then try to analyze a difference.


- Carsten

Carsten
Posts: 1466
Joined: Tue Apr 15, 2014 9:11 pm
Location: Germany

Re: Exporting to ProRes (packaging?) and frame-rate accuracy.

Post by Carsten » Wed Nov 06, 2019 1:52 pm

Sorry, I was wrong. I probably jumped on the reported number of frames in Ioannis first post too quickly. While in my tools the reported number of frames is identical for both DCP, MP4 and Prores, the frame rate reported by Media Info shows the same weirdness with the Star Wars Trailer I exported - variable, 24fps, minimum 23.994/max 24.006. This is in 2.14.11 OS X. And it happens with both ProRes AND MP4 exports for me.
When I import this file into DCP-o-matic, it reports the same number of frames as the original trailer, and shows it as 24.0000 in the content tab. But Media Info indicates the slight deviations. I guess FFMPEG causes this.

I quickly browsed through a number of other Quicktime and MP4 files on my machine, and most of them are reported with frame rate: constant by Media Info and either 24.000,25.000 or 29.970


FFPROBE doesn't handle this it seems:
----
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '/Users/carstenkurz/Movies/SWTRLRD.mov':
Metadata:
major_brand : qt
minor_version : 512
compatible_brands: qt
encoder : Lavf58.24.100
Duration: 00:01:31.54, start: 0.000000, bitrate: 135939 kb/s
Stream #0:0(eng): Video: prores (HQ) (apch / 0x68637061), yuv422p10le(tv), 2048x858, 131328 kb/s, 24 fps, 24 tbr, 90k tbn, 90k tbc (default)
Metadata:
handler_name : VideoHandler
Stream #0:1(eng): Audio: pcm_s16le (sowt / 0x74776F73), 48000 Hz, 5.1, s16, 4608 kb/s (default)
Metadata:
handler_name : SoundHandler
----

Now, the reason this may create possible issues in Premiere is probably that Adobe a while ago implemented a capability in Premiere to handle 'real' variable frame rate videos. These are quite commonly created by smartphones. When interpreted strictly by flagged or average frame rate, they cause audio sync issues. Before, Premiere probably simply ignored the variable rates indicated. Now it probably needs to do something useful when different rates are indicated in the file, leading to the interpretation issue Ioannis observed. Maybe Carl needs to dig into the Export parameters to find the reason.


- Carsten
Last edited by Carsten on Wed Nov 06, 2019 10:21 pm, edited 2 times in total.

Carsten
Posts: 1466
Joined: Tue Apr 15, 2014 9:11 pm
Location: Germany

Re: Exporting to ProRes (packaging?) and frame-rate accuracy.

Post by Carsten » Wed Nov 06, 2019 2:16 pm

I added some more info on this to the Mantis entry. Now, Carl may find a reason for this weirdness, but - does it cause any real issues when dealing with the export in video editors? I understand it is irritating upon first observation, but as long as it doesn't cause e.g. audio sync issues, I'd try to disregard it.

- Carsten

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