1080i @ 29.97 with interpolated frames, convert to 24fps

[johnny_b]

Playing back the Elvira Madigan Blu-Ray from Japan, the motion looks almost like video content, and seems slightly sped up (motion and sound) - regular IVTC does not work as the resulting playback is not smooth. My hunch from having read a few threads here is that they ran it at 25fps or 24.975fps and converted to 29.97fps, but I don't see duplicate frames, so maybe the extra frames were interpolated. I tried tdecimate mode 4 and then mode 5 but ended up with a 29.405fps encode. Presumably there's a consistent pattern to this and some way to convert back to 25fps or 24.975fps without too much difficulty (from there I can slow down the audio and the playback rate to get to 24fps) but it's a little beyond my basic scripting skills. Any suggestions?

[FranceBB]

Well, I'm gonna say what literally everyone else over here is gonna say: upload a small sample eheheheh
Frame rate questions are always tricky, so a small sample is worth thousands words.
Once we've got the original file trimmed, we're gonna be able to see what we're dealing with and come up with a script. ;)

[johnny_b]

Got it, thanks. Here's a sample:

https://www22.zippyshare.com/v/ZVgUzszU/file.html

Note the weirdness going on with the 'Sundsvall, Sverige' lower third in its initial frames. I tried a number of TFM settings but couldn't get fields to match to complete, uncombed frames. Testing these settings in AvsPmod seemed to give the best results - compressing now and will check after to make sure the motion isn't jerky. Going frame by frame I still get visual artifacts that are not great, like the horses going right to left I see a bridle twice in a frame, including once in the middle of a guy's head.

TFM(mode=2,cthresh=2,pp=6,slow=2,metric=1).tdecimate(mode=2,rate=24.975)

[johnny_b]

Well, that resulted in motion that wasn't smooth. My impression is also that it's still playing back quickly, even when I adjust to 24fps afterwards.

[Boulder]

Didn't check the sample as I'm at work, but would SRestore be useful here?

Something like:
#load source
NNEDI3(field=-2)
SRestore(frate=25, speed=-1)

[johnny_b]

Didn't check the sample as I'm at work, but would SRestore be useful here?

Something like:
#load source
NNEDI3(field=-2)
SRestore(frate=25, speed=-1)

Thanks, I'll give that a try. Oh, forgot to mention that the runtime is 87 minutes, vs the 'official' runtime of 91 minutes, which also suggests a PAL conversion to 29.97fps.

[poisondeathray]

Yes, some double rate deinterlacer, then srestore

The artifacts (the object boundary edge morphing, the text dragging) indicates that somebody used optical flow interpolation on this conversion from 25p to 59.94p , and then converted to interlaced

It's rare to use OF for retail BD ; typically blending or duplication would be used for the 25p => 59.94p step - because of those ugly artifacts (especially visible on text)

[johnny_b]

Great! That appears to have worked (I used 24.975fps to keep sync). There are a couple of shots here or there where the camera pans across the couple on horseback going through a forest or that sort of thing where the image isn't really smooth but this gives it a much more filmlike appearance.

[FranceBB]

It's rare to use OF for retail BD ; typically blending or duplication would be used for the 25p => 59.94p step - because of those ugly artifacts (especially visible on text)

Yeah, linear interpolation / optical flow would never pass a QC in most companies due to the artifacts. If we count the time in which it would pass a QC, then there's the fact that companies don't really want us to use that, like for instance if I receive a movie from a production company they would never ever allow me to use linear interpolation to perform frame rate conversion, while speedup or blending or duplication are generally allowed.

[wonkey_monkey]

Isn't "live" stuff usually standards-converted using interpolation? Like when the BBC shows news or sports footage from the US. It's very well done, too.

[FranceBB]

Isn't "live" stuff usually standards-converted using interpolation? Like when the BBC shows news or sports footage from the US. It's very well done, too.

Not really, live sports are always truly interlaced in both PAL and NTSC, so for instance if I was to receive let's say an NBA match from the U.S, I'm gonna get a 29,970i truly interlaced, which is gonna be bobbed to 59,940p via hardware and either blended or decimated to 50p and divided in fields to get 25i. This is done using an hardware signal routing, so you have:

Broadcast Quality 4:2:2 29,970i H.264 10bit BT709 SDR FULL HD Satellite feed ->
Satellite Decoder (SDI Cable) ->
Signal routing hardware (SDI Cable) ->
DFS (hardware that performs the conversion, namely bob to 59,940 and decimate to 50p and divide in fields to 25i) ->
Playout in which the clock and statistics and other things might be overlayed (SDI Cable) ->
Hardware H.264 encoder for consumer yv12 8bit H.264 BT709 SDR FULL HD output ->
Multiplexer ->
Consumer satellite or terrestrial feed output

https://media2.giphy.com/media/uTj8HUkabBUo4E2DEX/giphy.gif

[johnmeyer]

Isn't a lot of sports acquisition done at really high frame rates, like 120 fps? I thought this was especially true of the Olympics where one camera will provide output to various standards. If you get a high enough right frame rate (300 fps), you can simply decimate down to either 50 or 60 fps. No blending, interpolation, bobbing, or optical flow needed.

[FranceBB]

Isn't a lot of sports acquisition done at really high frame rates, like 120 fps?

The Olympics were something special cause Japanese are so advanced that they tried to push 8K 120p for NTSC and 8K 100p for PAL as a standard and they've been preparing for it since 2018. They were not ready in 2020, so delaying everything to summer 2021 actually helped them. Everything was also done in H.265 although there were speculations about H.266 VVC trials but the development of the codec was so far behind that there were not real time hardware encoders and therefore H.265 HEVC was picked. They've been arguing a lot on 10bit Vs 12bit as they were really trying to push 12bit planar, but in the end they used 10bit. That being said, we have no idea what the next 8K standard is gonna be and there are pretty fought battles between 8K 120p 12bit NTSC (and 100p PAL) and those others who want 8K 60p 10bit NTSC (and 50p PAL) to keep things aligned with the 4K standard which is currently 60p and 50p as the last thing anyone wants to do is to change frame rate of everything.



If you get a high enough right frame rate (300 fps), you can simply decimate down to either 50 or 60 fps.

That is true and that's what is done with very high frame rates.
That being said, I've been on a lot of PAL productions in PAL territories and I can tell you guys that I've seen all kinds of stuff going on.

Case 1:
All cameras shoot 50p and the signal goes into EVS. An EVS Operator picks the footage requested for replays and plays it live. The internal codec is generally DNX120 yv16 8bit. If a slow motion is needed, they slow it down on the fly to 25p and play it at 25p with repeated frames to 50p.
For instance, back when TVs were analogue and SD was around and VTR were used, 99% of slow motion were done by playing the tape at half speed, so you had 25i (i.e 50p for the normal shoots) and 25p (i.e tape played at half speed) for the slow motions.


In Case2 instead they would shoot in 100p and either decimate or slow it down accordingly.
I remember at the very beginning of UHD (we're talking about 2015) when having high frame rates UHD cameras was hard, so we had some cameras which were not being used for live coverage which were only dedicated to replays and were shooting in high frame rates FULL HD and then we upscaled the replay to have something really slowed down. If we needed a footage from one of the main cameras slowed down, then we would simply play it at half speed and deal with it at 25p.


Nowadays this is not such an issue as it was before, but I'm really really afraid of the next generational change and what that will bring 'cause ultimately it's gonna be us, broadcasters and contents creators, that will have to cope. :(

[johnmeyer]

Two things.

First, even 4K is overkill for most people reading this.

https://i.imgur.com/n7iroaB.jpg

Second, there are some amazingly high-speed broadcast cameras coming.

FOR-A brings 4K Ultra Slow-Motion camera and stadium solution at SVG Summit (https://imgur.com/a/ETJ2fi1)

[StainlessS]

First, even 4K is overkill for most people reading this.
Dont say that John - you make me feel daft.
After getting a 4K 28" monitor a couple of weeks ago, I also got a "4K friendly" Blu-Ray drive
[only 1 4K disk so far, and was not impressed with that movie "Us" {EDIT: No better than FHD, and a bit tedious really} ].
Also just ordered a 4K 10bpc 5.8" 16:9 phone, delivery due on tuesday [2018 Sony Xperia XZ2 Premium].
But, maybe you are right, as there seems only to be 7 4K Android phones [dont know how many 10bpc]
available in 2021/2022. [EDIT: Including the 2018 ordered one]

What power microscope would I need to see pixels on the phone when it comes ? ( :) )

EDIT: 8K does seem a bit over the top though.

[Boulder]

I think the biggest benefits in UHD when watching from further away are increased perceived sharpness and HDR. However, some releases are just pure crap compared to the older Blu-ray releases (looking at you, Lord of the Rings).

[FranceBB]

However, some releases are just pure crap compared to the older Blu-ray releases.

Most of the times, in terms of resolution, old movies are upscaled to UHD, however the biggest advantage comes from HDR and that's not fake at all, as the overwhelming majority of movies were shot in 10bit and Slog or Clog or LogC anyway, so logarithmic curves perfect for HDR, so converting them to PQ is a piece of cake and really gives out something more and better to the viewer. Of course, cameras in the past didn't have as many stops / nits they have today, but still they were well over the SDR 100 nits limit that the older standards imposed, so, you see, even if you don't necessarily see more "pixels" in UHD Remasters, you definitely see more nits and they're not all made up.


(looking at you, Lord of the Rings).

probably some others are just bad, who knows XD

I think the biggest benefits in UHD when watching from further away are increased perceived sharpness and HDR.

Definitely, for me the biggest thing is 10bit, HDR and finally finally finally 50fps progressive rather than 25fps interlaced bobbed by the TV. That thing alone (progressive vs interlaced) is worth a lot of more perceived sharpness and A LOT LESS ALIASING which I really love. No more jumpy graphics, no more jumpy subtitles etc. The way it should have been in the first place since the HD switch (but it wasn't)! :D

[Dogway]

IMO the biggest benefit is the increased color gamut, but this goes hand to hand with HDR (increased luminance) and hence increased bitdepth to allocate all the extra data.

This isn't possible for movies filmed digitally since about 2001 (except recent titles), but for those recorded on film stock you can recover the dynamic range and film gamut. Resolution is also a good thing for old movies in such way that having a remastered UHD of the last century is the closest to a digital master you gonna have.

For 4K your range of optimal pixel discern is within 2 and 3 meters of distance (for 55" and 75")
As for TV set size, there are some standards, mixed usage, SMPTE 30 and THX recommendation.
SMPTE 30 (30º FOV) is the standard for watching movies at home with nice enough immersion. That means from a distance of 2.5 to 3 meters -most- for 55" and 75".

I think 65" or 75" is ideal for 4K.
With 1080p if you are a bit closer than 2 and 3 meters using a 55" or 75" TV set you are going to discern pixels.

Link (https://www.rtings.com/tv/reviews/by-size/size-to-distance-relationship)

[manono]

(I used 24.975fps to keep sync)
Audio synch isn't affected either way.