Discussion Amazon Prime and 'true' 24fps

[Jimc115]

Amazon doesn't convert content as far as I know....it's encoded by the vender and submitted...Amazon either accepts or rejects it.
Amazon is getting more lax on its requirements....but this is kinda old also as they do accept variable rate content now. (That might
by subject to the fact that's all that may be available).

I can tell you Paramount is the most guilty....HBO/MAX is still pretty strict. Even UK content on there is 25fps. Disney is probably the most
strict.

The lag in making 24fps standard lies with the broadcasters unwillingness to upgrade their equipment. It will probably take a standards change
by the government to force it. There's absolutely no reason to keep 23.976 now. The only reason it ever existed was because Black and White
went Color and they needed a fraction of space to transmit the info. Digital doesn't need that extra space.

Those are mezzanine requirements, basically telling the studios not to do any frame rate conversion since Prime accepts all of the standards. I believe that Amazon is doing the framerate conversion in their encoding pipeline and not the studios/providers. I have some older movies from Amazon in 2018/2019 which are 23.976 and are now 24fps. If you download a movie from directly from Max and the other from Max via Amazon one will be 23.976 fps and the other 24 yet the two sources are identical (aside from framerate). Lastly, Amazon leaves the framerate as is for any movie or show that have an intro (Starz, Cinemax, MGM+, etc).

For best results, we recommend exporting your videos at the same frame rate at which the content was shot and edited.

So...I don't think Amazon is reencoding anything. They do however have higher requirements for bitrate, so you will not get the same video as from the original site.
Movies come and go....when they go...Amazon deletes them...when they come back, new video files are provided....so it's easy to see where a video from 2018 would
be different than one on currently. I'm not actually sure Amazon could reencode the videos if they wanted.....most providers stipulate they must remain untouched.
You use to see that with subtitles...if none were included, they couldn't be added. With technology though, subs can be generated automatically without changing
the video. Think of it this way....it was suggested once that Adobe would add an invisible watermark to materials created on pirated software. Adobe withdrew the
idea when it was point out that by changing the copyright holders work without their permission would in itself be a copyright violation.

 

[RedFox 1]

Amazon doesn't convert content as far as I know....it's encoded by the vender and submitted

That is exactly whats happening I do believe.

 

[psig33]

Amazon doesn't convert content as far as I know....it's encoded by the vender and submitted...Amazon either accepts or rejects it....

I think it's the total opposite. If it would be the content providers actually doing the framerate conversion than why would they only do it to the mezzanine files delivered to Amazon and no one else? Netflix accepts the exact same framerate as Amazon... I've yet to see another 24 fps frame duplicated video from another provider, so that idea doesn't really hold up.

In the case of Max ... why would they go to the trouble of encoding two mezzanine files, one at 23.976 for Max and one at 24fps for Max via Amazon?

I may actually ask a lead Amazon Video guy in another forum, hopefully he replies...

I'm not actually sure Amazon could reencode the videos if they wanted.....most providers stipulate they must remain untouched.

Amazon ALWAYS reencodes the mezzanine files. They can't stream a 220 Mbps YUV 4:2:2 ProRes file with PCM audio to customers

For best results, we recommend exporting your videos at the same frame rate at which the content was shot and edited.

Wouldn't converting a native 23.976 video to 24 fps go against those recommendations?

 

[BCloud]

Amazon doesn't convert content as far as I know....

Of course yes, they get the source material and they convert as needed, it's why they changed their encoding settings for VBR a few years ago to a worse VBR (why ? we don't know) and it's why today they are converting their content to 24fps by adding a duplicate frame every 40 seconds. It's easy to verify. Take a 24fps movie, play it with vlc and type "E" to forward image by image, watch around 0:20 1:02 etc. adding each time 40 seconds, you will see that sometimes you type "E" and the frame is exactly the same.

I saw 23.976fps movies/tv shows that are now 24fps, I have them in h264 and I redownloaded them in hevc and I can't replace the file because it's 24fps. It's not the codec because if I redownloaded the title and it's also 24fps in h264, the audio track is exactly the same, so only the video has changed.

 

[Jimc115]

I think it's the total opposite. If it would be the content providers actually doing the framerate conversion than why would they only do it to the mezzanine files delivered to Amazon and no one else? Netflix accepts the exact same framerate as Amazon... I've yet to see another 24 fps frame duplicated video from another provider, so that idea doesn't really hold up.

In the case of Max ... why would they go to the trouble of encoding two mezzanine files, one at 23.976 for Max and one at 24fps for Max via Amazon?

I may actually ask a lead Amazon Video guy in another forum, hopefully he replies...



Amazon ALWAYS reencodes the mezzanine files. They can't stream a 220 Mbps YUV 4:2:2 ProRes file with PCM audio to customers



Wouldn't converting a native 23.976 video to 24 fps go against those recommendations?

Go ahead and ask your Amazon friend...

You could have just done that in the first place...BUT...if you honestly think the only place 24FPS videos appear are on Amazon...you need to wake up
and join the real world.

If you want to make a point...try doing so without being a jackass.

 

[Salotto]

Hi everyone, everything fine?
I think some people are confusing this aspect of the FPS.
The existing FPS in these videos are: 23.976, 24 and 25.
Any value other than those quoted is not real.
If you are having difficulties synchronizing audio, you should always change the FPS of the respective audio to synchronize with the downloaded video.
The possible fps changes will always be these:

23.976 --> 24.000
23.976 --> 25.000
25.000 --> 24.000
25.000 --> 23.976
24.000 --> 23.976
24.000 --> 25.000

 

[BCloud]

if you honestly think the only place 24FPS videos appear are on Amazon...you need to wake up
and join the real world.

I think he talked about "24 fps frame duplicated video" not a simple 24fps. Videos exist in several framerates of course, but here we have Amazon that want to convert a native a 23.976fps to 24fps with a duplicated frame every 40 seconds. On Amazon we have videos that are really native 24fps and others that are converted from a 23.976fps without changing the length and that is the problem, they don't want to convert again the audio and subtitles so they just added a bad argument to their settings to keep the same length as before, and it introduces duplicated frames. Maybe there is a reason we don't know but it's a bad choice for me.
If they really want to have a 24fps, the good way is to convert the audio track too to the same length, and the problem will not exist.

On other providers you can have 24fps of course, but as what I see now, they are native 24fps and no "trick" added in their settings.

 

[Jimc115]

I think he talked about "24 fps frame duplicated video" not a simple 24fps. Videos exist in several framerates of course, but here we have Amazon that want to convert a native a 23.976fps to 24fps with a duplicated frame every 40 seconds. On Amazon we have videos that are really native 24fps and others that are converted from a 23.976fps without changing the length and that is the problem, they don't want to convert again the audio and subtitles so they just added a bad argument to their settings to keep the same length as before, and it introduces duplicated frames. Maybe there is a reason we don't know but it's a bad choice for me.
If they really want to have a 24fps, the good way is to convert the audio track too to the same length, and the problem will not exist.

On other providers you can have 24fps of course, but as what I see now, they are native 24fps and no "trick" added in their settings.

Thanks and I know you are only trying to help...just like I was. I'm done...and no reflection on you. I walked right into that childish trap...my own fault.
I know the logic...if it's 23.976, then there are 23.976 frames per second...You can't add a partial frame to make it 24. Whoever is to blame..it's just bad encoding.
Besides the removing extra frames trick....Topaz AI has a Frame Interpolation setting you can use to remove duplicates. It also has a stabilization filter to reduce
the judder on fast motion scenes. I haven't tried either, but there's a fast setting and since you can do it without enhancing or changing resolution, it might
work well...I'll try it and let you know. As for the frame Interpolation, I'm guessing it drops the duplicate and creates a new frame from the one prior and the one after,
smoothing the motion.

Anyway...I'm staying out of the argument now....I'll do some test runs on Topaz and let you know.

 

[psig33]

You could have just done that in the first place...BUT...if you honestly think the only place 24FPS videos appear are on Amazon...you need to wake up
and join the real world.

I know that real 24fps content exist, I have a few blurays at are 24fps. But we're talking about streaming services here, specifically content that has been converted from 23.976 to 24 fps by duplicating frames. I've downloaded content from just about every US provider and Amazon is the only one that exhibits this behavior. You claimed that the studios were the ones doing the framerate conversion and I just pointed out that it's unlikely as it goes against recommendations and if that were the case, other streaming services would also be affected, not only Amazon. I don't see how that is being a jackass, but if name calling makes you feel better, good for you.

 

[Steve55]

For those people experimenting with this, what effect does it have on the audio to remove the duplicated frames?

 

[psig33]

For those people experimenting with this, what effect does it have on the audio to remove the duplicated frames?

No effect on the audio because the length stays the same.

 

[Harpers Tate]

The input is 24fps. The output is 23.976fps. All other things being equal, the output is imperceptibly slower; longer duration.

Resampling the frame rate removes 1 frame per 1001 but maintains exact duration by reducing the fps from 24 to 23.976 at the same time. Thus AVsync is maintained.

Retiming the frame rate (where the 24fps input is frame accurate) does increase duration and therefore AVsync will not be maintained. The audio has to be slowed (0.999x) to match. That might be a separate command depending on what editor your are using.

If one were to simply remove extra frames (eg using a video editor) then that, too would affect AV sync unless the audio were clipped in the same places - and that might well be audible. So you'd have to either reTIME the edited video to 23.976 and that would then restore duration and sync; OR speed the audio (1.001x) to sync it with the edited true 24 video.

 

[James]

I'm not sure if my Nvidia Shield actually supports true 24fps

I believe it does (using Kodi)

but I'd be fairly sure that my now-ancient Panasonic plasma TV (circa 2009) doesn't

If it supports 23.96 Hz it will very likely sync to 24, as this is only a very small difference. Worth a try.

 

[jake2010]

Amazon Prime frame rate is really disappointing.

For example, the TV series "Gold Rush" season 2. It is filmed at 25 fps and it was previously 25 fps on Amazon. But with the Amazon Discovery Plus channel it was changed to 30 fps. Not only did they duplicate 5 extra frames per second, they blended the frames. So the extra frames are a combo of 2 frames with a ghosting effect.

The video is fine on the regular Discovery Plus site. It is just the Amazon Prime video that has the frame rate issue.

 

[BCloud]

I think it was converted for NTSC TV, US TV is around 30fps with a mix of progressive and interlaced frames (3:2 pulldown)

I saw recently his dark materials on pass warner, it's an UK show (BBC) filmed in 25fps, and it's provided in 23.976fps. I don't know how they did the convert because it's awful to watch, every 2 seconds it seems to speed up during 2 or 3 frames.

 

[psig33]

I'm not sure what is going on with Amazon but it seems they have reverted back to 23.976 (or at least starting to) ... I don't think it's pure coincidence that I found 15+ movies that were 24fps a few weeks ago and are now back to 23.976. I first noticed something strange with the Max channels, Spanish as a second language is a hit or miss on Amazon Max, as not every movie has the additional language tracks, but through Max directly they do. I started seeing movies that have been on Amazon Max for a while getting the Spanish language track added. So I went back and re-downloaded various movies and noticed that all of them were 23.976. I thought maybe it was a Max thing, so I downloaded a few movies from Prime which I already have at 24fps, and behold, they are now 23.976. I did find a few movies that remain 24fps, not sure if it hasn't been processed yet or what, since I just noticed this behavior today.

These "new encodes" have a slightly lower file size. However, I cannot say if they are better or worse since I have not inspected them closely or done any frame comparisons.

 

[BCloud]

Yesterday I just found that the CVBR version of a movie is now the original 23.976FPS and CBR and HEVC are still 24FPS, so yes there is maybe something but I don't know what.
I'm trying to find a plugin or something to know before downloading because I can only analyze the CVBR throught the browser and I have to download the CBR and HEVC version to know...

 

[psig33]

These "new encodes" have a slightly lower file size. However, I cannot say if they are better or worse since I have not inspected them closely or done any frame comparisons.

After Inspecting a few of the old 24fps VBR encodes VS the new VBR 23.976fps ones, the quality has degraded. The new encodes don't retain the grain structure very well and creates areas that seem blotchy. Overall it has less finer details and temporally less cohesive. The I frames in the new encodes look similar to P/B frames in the old encodes. They've must of done something to the encoding settings because on some movies, the size difference is not that large, but yet the old encode looks better. On some movies, there is a clear size difference, 1-2gb. Sad day if Amazon once again reduced their quality...

Yesterday I just found that the CVBR version of a movie is now the original 23.976FPS and CBR and HEVC are still 24FPS...

Yep, ran into the same issue on a few movies myself, VBR version is the only one at 23.976FPS with some, while others only the CBR was 24FPS. Maybe it will take sometime for their system to go through their entire catalog

 

[Jimc115]

I think it was converted for NTSC TV, US TV is around 30fps with a mix of progressive and interlaced frames (3:2 pulldown)

I saw recently his dark materials on pass warner, it's an UK show (BBC) filmed in 25fps, and it's provided in 23.976fps. I don't know how they did the convert because it's awful to watch, every 2 seconds it seems to speed up during 2 or 3 frames.

It's not just you....it bothers some people more than others. I notice it right away also...a steady skip every few seconds. I don't find 23.97 to 24 as unbearable.
I don't actually know if you can correct the 25fps to 23.976fps. Given it's higher quality....I might try running it through Topaz to see if Stabilization helps with the jitter or to see if it would cause what jake describes as a ghosting.

What's the movie title

By the way...His Dark Materials was originally 25fps on HBOMAX as were almost all BBC shows....the Blu-Ray release in the US is also 23.976fps while 25fps
in the UK.

 

[Harpers Tate]

I only find 24fps a nuisance if they have done it badly by starting from a 23.976 source and duplicating the odd frame as required to change the fps (resampling). That IS something they do. If it has been converted (from whatever source) on an exact frame-by-frame basis - either telecined from film at 24 exact or, if from an already 23.976 source, retimed (rather than resampled)(which is also something they do - and which of these it is can only be determined by close examination) then it doesn't bother me at all. There is no material difference. That said, I do tend to convert to 23.976 for the sole reason it is a defacto commercial standard. I doubt you will ever find a commercial BD or UHD at 24 exact.

25 fps can easily be converted to 23.976 (or 24 if you prefer) frame by frame (so, absolutely accurately; no blurring or interpolation); avidemux will do this, frame accurate and allows the audio to be retimed to maintain lip-sync. Doing so does extend the duration - to the "correct" value (for movie content).