For example, ffmpeg's pitch correction using "atempo" filter (WSOLA) is average and might present artifacts depending on source audio.
ZTX (was Dirac) is another algorithm that's commercial and pretty much artifact free.
Btw, sound studios responsible for the 24-25 pitch shift often have the possibility to process the pitch shift on separate dialogue, music and effects tracks, limiting even more the artifacts in the converted output.
This post was 2016. Six years later, this is no longer true, at least here in my area (Montréal). At my work in a post-production company, we finish around 8-10 long form fiction movies a year and a bigger number of shorts, and I would say around 90% of thoses projects are now shot 24.0 fps.
All high-end cameras like the ones from Arri, RED and Sony can switch easily between 23.976 and 24.0 since many years. The sound recorders can now too, like the Sound Devices, which is the most common brand used (at least here in North America). The choice of shooting in 24.0 was already available in 2016, but not every gig would be used to shoot 24.0 so they chose 23.976 just to be safe, I guess.
Also, in 2016 television was still a major deliverable, but this has changed. Video on demand, which supports any framerates, is now the main distribution channel when a movie has finished playing on the big screen.
Documentaries are more of an exception because they are still aimed at television and also, they often use old footage which was telecine'd at 23.976 so it's easier to edit when everything's 23.976.
> Video on demand, which supports any framerates, is now the main distribution channel
But all the major VOD services, be it Disney+, Netflix, Hulu,... still mainly use 23.976 or 29.97 fps for their video distributions.
I don't know what your production company mainly works on, but these NTSC frame rates ares still the norm across the whole cinematic industry, and it's not going anywhere. It's not limited to documentaries at all.
The YouTubers etc. do use 30/60 fps more often OTOH.
Good question. Last time I've submitted to Netflix, it was 24, but it goes through a third party "packaging" company before going to Netflix.
So some of them might reconvert to 23.976 even when we submit 24 fps masters as per the contractual agreement. Maybe you are right. I will check.
Low budget web series shot at 23.976 even get delivered and played back at 29.97i on some local platforms here in Canada (Crave, Noovo, tout.tv), so anything's possible nowadays.
On the other end, Blurays can be encoded at both 23 and 24, and Vimeo, Youtube, etc all support 24fps. So 24 fps exists, not just on DCPs.
By the way, the loss of quality from going to/from 23.976 and 24 is not much. I've never heard any artifacts from that kind of conversion. But since cinema theatres are most likely to have a better sound system that a home system, I think it makes more sense to have the unconverted mix playing in the cinema and not vice versa.
At the moment, blu-rays are also still predominantly 23.976p.
I do agree we should actively push this relic out, though. Wish Netflix etc. can do more to normalize whole number frame rate to end this. Unfortunately considering TV industry are still using 29.97i for broadcasting, I don't see it's going to happen any time soon. And it's worse in other countries like Japan.
Most other countries apart from Japan use 25i for television broadcasting, with none of the complexities of dropframe. Sadly the general consensus was to go for 1080i25 rather than 720p50 for HD.
But how would you convert from 23.976 to 24? Either you will have a repeated frame once every 1000 frames, or you would need to interpolate every single frame.
Surely the first solution would be preferable. But it would still lead to more than one jitter per minute. I wouldn't call that "no artifacts".
Considering that slowing down FPS doesn't alter the images, and audio can be resampled with practically no audible artefacts, I doubt that quality would ever be an issue. As long as it's done with the proper care of course.
I would think the main consideration is workflow these days.
Not well versed in video production but really interested layperson.
I understand that the two main reasons for 23.976/24 fps are that it’s:
1) been the standard for a really long time so you know everything will more or less support it (cinemas/vod/broadcast tv).
2) is now in people minds as what film should look like (in that 60 fps somehow looks “off” because we’re trained to expect 24 fps).
Given that analogue broadcast tv is dying off and that digital OTA tv is a similar case to vod in terms of codecs (maybe not receiver support?), wouldn’t a stopgap be some multiple of 24 fps (e.g. 48fps) that would allow better motion handling without the pace seeming off?
I think the real reason HFR isn’t used much in cinema is that it ends up exposing a lot of the choreography, set design, special effects, etc. as fake, where before our brains filled in the details due to the low information rate and blurry frames.
Watch either of Ang Lee’s HFR movies (Billy Lynn/Gemini Man) and you’ll understand what I mean. HFR breaks suspension of disbelief. I didn’t want this to be true but I’ve come to accept that it doesn’t really have a place in cinema at least for now.
Wasn’t HFR mostly used in 3D films to get rid of the skipping in high paced scenes? If I remember correctly the first HFR film was The Hobbit?
(I worked in the industry at the time on the technical side, but I’m not a film buff, so the details are forgotten a long time ago. All I remember is that there was a huge amount of work involved to get all the equipment upgraded to support HFR. Cinemas had to upgrade both their playback servers and projectors for thousands of dollars. All for less than a handful of films.)
Production audio and video recorders generate or intake an SMPTE timecode signal, and stamp recordings with this timecode.
This timecode format is a timestamp with seconds resolution plus a frame count within each second. To properly sync, all the timecode generators must use the same framerate. In other words, the audio recorder’s timecode framerate needs to match the camera.
Yes, sound needs to be recorded with proper metadata, otherwise the sync process with the image is going to be pretty tedious. We could just record with a "dumb" audio recorder that doesn't write timecode and fps metadata and it would sync up by hand to any camera FPS (23.976, 24, 25, 29.97, etc). It's not just practical for any professional projects.
The funny thing with timecode, which is hh:mm:ss:ff, is that the frame count is done at 24 frames, even at 23.976. So 1 frame of 23.976 is longer in actual "real time" duration than 1 frame at 24 fps. This can get confusing when going from and to 24/23.976.
There are more sophisticated workflows where the audio is recorded at 48.048 kHz (0.1% faster sample rate) called audio pull-up (or pull-down). The technique is used when shooting, for example, a TV spot, with a film camera at 24 fps. Since the 24 fps picture will be played back at 23.976 at the edit, the audio will follow the same speed down because it will itself play at 48.000 kHz instead of 48.048 kHz. I'm not sure that many productions still shoots TV spots in film, though, contrary to fiction where film is still being used sometimes.
But the timestamp is not recording actual seconds, right? Half the time it's recording intervals of .999 seconds. That is much weirder to handle than merely having the right framerate.
The time code is always incrementing by one frame at the given frame rate. For any of the NTSC-derived framerates, there are then two ways of incrementing. You can increment as if the frame rate is integral--so after 30 frames at 29.97 fps, your timestamp will show that 1 second has passed. The other option is a "drop-frame" timecode, where you skip over certain numbers when incrementing.
In all cases, the time code increments at the frame rate you are using.
I'm guessing, because I'm bored, and hopefully an expert will confirm or correct, but I think it means that they place sync markers every 24th of a second, to make syncing with video efficient.
Because 60fps and 24fps don't look alike and video shot at a very high frame rate can look off to an audience.
Remember also that typically a 1/2 rule is followed where the exposure of each frame is half the time of its display. So for each of the 1/24s intervals, an exposure is made for 1/48s. A shorter exposure would have less motion blur but look jittery. A longer exposure would look too buttery. People are extremely used to 1/48s exposures displayed for 1/24s (or similar).
48fps video in the Hobbit movies was very negatively perceived. It looked too much like a video game.
You're in the minority, I think. The Hobbit was shot in 60fps and most people found it very uncomfortable to watch. It felt like you were watching a movie set rather than a movie. Suspension of disbelief is pretty important for cinema and 60fps really messes with that.
I also think most jerkiness in 23.976/24 is due to incorrect display settings leading to dropped/skipped/repeated frames. If your display can match 23.976, even panning scenes look pretty smooth. It's the jitter that messes with our brains and looks bad.
It's not jitter that bothers me, it's the stop motion effect. It's especially bad with action sequences that have a lot of closeup shots.
This is basically every movie with any sort of action in the past decade or so. If you do closeup shots in on some fast action in 24fps you don't have to worry one bit about choreography, since it'll just be a choppy blurry mess and nobody can tell what's going on anyway.
I can agree things like sports are a lot better at high frame rates. You want to see what players are doing precisely in a live setting. But people don't watch sports in movie theaters.
I'd argue stylistically the lower frame rate works a lot better on a big screen. There's also the fact that high frame rates on a big screen seem to cause some people to get motion sick.
I personally have no issue w/ action scenes which are shot at 24fps. Yeah, there is a fair amount of blur but it all seems natural (at least on a cinema projector), and conveys the fast movement, even if it might not be precise.
Take Jackie Chan's Drunken Master epic final fight scene for example - yes it's a bit blurry but I can make sense of everything going on. If anything it enhances the feeling of action - if this was shot at 60fps, it would look much more "real" and be a lot less enjoyable.
There are always a lot of unsatisfying hand-wavy answers to this question just saying that high framerate video looks "off" or "like a soap opera". I'd like to point out that the biggest factor here is probably the lighting.
Cinematographers have to pick particular aperture and ISO to get the depth of field and film grain they want, so they can only really adjust exposure though shutter speed. If you double the framerate, the minimum possible shutter speed halves. Therefore (unless you are shooting outside on a sunny day) it is very likely that your shot is underexposed, and the only thing you can do about it is add more lighting. This can be both logistically complicated and technically very hard to pull off without looking unnatural, especially in scenes that are supposed to be dark and moody.
I wonder what the viewing experience would be like if it were shot in 48fps, but then most alternating frames were dropped so it still felt like 24fps, except for certain key visual sequences - action, big effects shots, etc. You could even transition between the two frame rates over a few seconds.
As others have said, 60fps can actually look "off" to some audiences. It definitely looks "off" to me, and I can't quite put my finger on it/why. It could just be my age (late 30s) and my brain grew up on 24-30fps.
Many new TVs interpolate 24/30 fps to be 60fps. This is knows as "The Soap Opera Effect", and has been written about here before. [0].
To me, 24/30fps feels "smooth", almost "buttery". 60fps feels crisp. 60fps feels almost too real. It makes it more difficult for me to suspend disbelief, whereas 30 makes it easier to suspend disbelief and get lost in the imaginary world that's being presented to me as if it were real. It's really difficult for me to explain....
The horrible "motion smoothing" interpolation is the first thing anybody should turn off on a new TV. I absolutely hate it, just ruins the look of movies!
I've completed a video shot at 24fps, some footage was recorded at higher frame rate for slow motion, but you can tell the diference. The 24 fps is the best, as it looks and feels better in the eyes for most people and also my audience :)
To be fair, the first line of the response heavily qualifies the answer: "Truth is that most digital projects shot for either broadcast or cinema use 23.976 instead of 24 in the U.S."
I think they mean the VOD service doesn't restrict the creator on what frame rates they can author their content in, the box just makes it work for whatever the display requires.
For example, ffmpeg's pitch correction using "atempo" filter (WSOLA) is average and might present artifacts depending on source audio.
ZTX (was Dirac) is another algorithm that's commercial and pretty much artifact free.
Btw, sound studios responsible for the 24-25 pitch shift often have the possibility to process the pitch shift on separate dialogue, music and effects tracks, limiting even more the artifacts in the converted output.