Bug(?) in exporting 50fps progressive from Premiere via Adobe Media Encoder (original 25i)

[jimhoyle]

My Sequence in Premiere is 1920x1080 Upper Field First (interlaced) 25 fps. So my material does have 50 frames (just divided into fields), so the motion is (or should) be smooth. When I Export directly from Premiere (not through Adobe Media Encoder), I get the expected result. The motion is smooth, file is 50 fps. When I send to AME to export, the result is completely different. Motion is 25 fps (not smooth) even though metadata says 50 fps. So this seems to be a terrible bug.

How do I export truly at 50 fps (motion compensated deinterlacing to progressive) via AME? Because I have tons of files, it's impossible to export one by one inside Premiere.

By the way has deinterlacing of Premiere changed over the years (say in 5 years) or does it use the same algorithm as before? I'm not sure if Premiere originally supported motion compensation deinterlacing, probably not? When did it start supporting that?

[Ann Bens]

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@jimhoyle wrote:

 So my material does have 50 frames (just divided into fields), so the motion is (or should) be smooth.

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NO, your footage does not have 50 frames they are 25 whole frames 'cut' up in 50 half frames (interlaced).

This is quite different from 50 whole frames as in progressive.

If you want to export your 25 frames to 50 frames turn on frame blending or optical flow.

On a side not it will never look as good as real 50p.

[distriller]

Yes, not perfect full frames, but most of the time good quality motion compensated deinterlacing produces fairly convincing results in my experience. When good quality deinterlacing works for 1920x1080 material, for me it has been mostly only horizontal or nearly horizontal vector graphics whose edges show visible problems, especially when rotating slowly. In what situations do you find 25i considerably worse compared to actual 50p? I'm interested because I have to deal with interlaced material daily. I do dislike interlacing, because it causes so many unnecessary problems.

For the solution you provided, it did not work for me. I don't want frame blending, but optical flow did not work for this situation. As I wrote, direct export from Premiere already produces a good quality deinterlaced 50p without optical flow. But Exporting the exact same via Media Encoder gives 25 images per second as a result, regardless of whether optical flow is on or off. (We are talking about converting 25i aka 50i to 50p.)

[jimhoyle]

Is there no comment on this? I would that this is clearly a critical bug. Why does the direct export from Premiere cause a completely different result than exporting the exactly same thing with the same export preset in AME?

[jimhoyle]

Oh I accidentally sent my Nov 30 post with a wrong account. There's no edit/delete button so I'll just leave it like that, but the account was accidentally incorrect.

[Warren Heaton]

i50 (also called i25) can be de-interlaced to p25, not p50.  It's a format issue, not a Media Encoder issue.

[jimhoyle]

Warren, unfortunately I don't understand your message.

1. What do you mean 50i can't be deinterlaced (or converted) to 50p? I have done it countless times very successfully.

2. What do you mean by format issue? As I wrote, Premiere exports (converts to) 50p very well, AME exports only to 25p (even though the container is supposedly 50p), but the export settings are identical so the behavior is illogical. But the file format does not have problems with 50p.

I'm surprised that this issue doesn't seem popular. For me, this is super important because I work with 25/50 fps interlaced/progressive files daily.

[Warren Heaton]

@jimhoyle 

Converting i25 (also called i50) to p25 has full vertical resolution per frame to work with when creating the progressive frames even though there is a temporal offset.

Converting i25 (also called i50) to p50 has has half-vertical resolution per frame to work with when creating the progressive frames.

It has nothing to do with me or Premiere Pro but rather the PAL/SECAM/ATSC broadcast formats and it’s very important to be clear about best practices.

Perhaps most importantly, i25 and p50 are not designed to be interchangeable.  It's not like p24 having 3:2 pulldown as an option to get to i29.97 or p23.976 to pulldown to i29.97 and then pull up to p23.976.

Premiere Pro’s Optical Flow is great for remastering frame rates and if you’re happy with the results then there’s less to worry about when it comes to format settings or best practices.

[jimhoyle]

Yes, what you state about the temporal theory is the basis of 25 fps interlaced. But, as I wrote, there are only certain scenarios where high quality motion compensated conversion to 50p is considerably less than satisfactory. In other words, most of the time conversion to 50p is possible with reasonable quality (in the future AI will fix it to perfection, but that's another story). I'm interested in practical results because that's what I have to work with. We can by all means separate out best practices and other useful practices.

I am not sure if you understand what I have written about the export process. Premiere exports a satisfactory result but when exporting the exact same thing with AME, the result is not the same, and useless for my use. This discrepancy is not about broadcast formats, rather it is a logical discrepancy between different result for the same export settings. One or the other is not intentional (I would suggest that the AME behavior is not intentional).

As I wrote, Premiere Pro's optical flow is useful for certain cases, but in my example, it is of no use at all. Premiere's direct export already does what I need, without optical flow. So the main question is, why is there the export discrepancy and why is it not fixed?

In the mean time, I guess I have to export dozens of videos manually one by one in Premiere, as AME is broken for this.