Recently, I have been recording a few short movies with my HTC One and while looking at the videos on my PC, I noticed that the frame rate is variable. I initially thought that the video was shot at 30fps under the Normal setting but the frame rates are all over the place. For example, in one video the minimum frame rate is 17.004 fps and maximum frame rate is 29.791 fps, as measured by MediaInfo. However, each video's frame rates differ slightly. Additionally, the front facing camera records very choppy video. The frame rates are around 6 fps. Is this normal?
I am curious to know why the frame rates are variable and if there is any way to get a fixed frame rate locked in. Do all video-capable smartphones have this variable frame rate feature?
Before I forget, I have also been taking some photos in varying light conditions, day and night, and the f-stop on all photos seems to be f/2, without exception. I found that strange as well.
Thank you for the help.
The variable rate is to ensure it is not underexposed. Imagine it is fixed exposure, so varying shutter speed. It's more pronounced in darker environments.
The focal length and the aperture of the lens are fixed, so the f-number is a constant.
BenPope said:
The variable rate is to ensure it is not underexposed. Imagine it is fixed exposure, so varying shutter speed. It's more pronounced in darker environments.
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I appreciate the explanation. I worry that a low frame rate will affect the smoothness of the video. I could already see in my videos that motion was somewhat weird at times, especially in night scenes. Any smartphones out there with a fixed rate for video (ie. 24 or 30fps)?
Hi everyone, I saw that during idle mode the image is like a strobe and in the settings the image size is blocked 16: 9 0.9 megapixels, and impossible to change. I saw the same problem on my galaxy s9 + and also a galaxy s7. I saw on the net that a lot of this problem !? how to solve it? thank youView attachment 4661145
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krz_ayman said:
Hi everyone, I saw that during idle mode the image is like a strobe and in the settings the image size is blocked 16: 9 0.9 megapixels, and impossible to change. I saw the same problem on my galaxy s9 + and also a galaxy s7. I saw on the net that a lot of this problem !? how to solve it? thank you
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its how slow mo works. it takes high frame rate video with lower quality. iirc the slow mo you will take is 720p in 480fps. since lamps flicker at around 50-60hz, and you have 480fps which means you will have a faster shutter speed, thus the camera is capturing light faster than how lamps flicker
ammar18 said:
its how slow mo works. it takes high frame rate video with lower quality. iirc the slow mo you will take is 720p in 480fps. since lamps flicker at around 50-60hz, and you have 480fps which means you will have a faster shutter speed, thus the camera is capturing light faster than how lamps flicker
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ok thank you friend, and so it is normal that we do not know anything in the settings and the lights flash! then all slow motion videos will be in poor quality as long as the light is by "day"? A friend made a slow motion video with an iphone 7 in a dark room, and the slow motion is great! I try me and it is awful ... where I asked myself these questions.
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krz_ayman said:
ok thank you friend, and so it is normal that we do not know anything in the settings and the lights flash! then all slow motion videos will be in poor quality as long as the light is by "day"? A friend made a slow motion video with an iphone 7 in a dark room, and the slow motion is great! I try me and it is awful ... where I asked myself these questions.
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yes, it is normal if lights flash, especially at higher fps
the default option for the slow mo on the Note 9 is super slow mo, which is 720p at 960fps. it requires quite a considerable amount of natural light, as artificial light, or lamps flicker. to get the normal slow mo, go to your camera settings, edit camera modes, rear camera and check Slow Motion. that way you can get higher quality slow motion at a reduced frame rate which reduces flickering.
on the side note, when you use super slow mo, you can remove flickering by playing the video, press the three dots at the upper right corner, and tap on Remove Flickering.
ammar18 said:
since lamps flicker at around 50-60hz, and you have 480fps which means you will have a faster shutter speed, thus the camera is capturing light faster than how lamps flicker
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These days the modern lamps can have all kinds of flicker frequencies and effects, especially at higher frequencies, due to using (cheap and/or small space) electronics to convert and control the mains voltage to the lamp's voltage/current, and the conversion has its own higher frequency.
The end result can still be flickering, just that it can also look different than the older 50/60Hz effect, depending on how the camera works. For example, it can show as lighter and darker stripes instead of brightness changes in whole frames.
For examples as seen right at my desk with the super slowmo preview: LED backlight display of my slightly old work laptop flickers wildly and full display effect; my newest LED backlight 4K monitor is steady; my older CCFL-backlight monitor shows a slow slightly colored rolling wave effect through a rainbow of shades (though in this case the effect could be caused by the actual LCD-panel control instead, or the combination of the panel and backlight both varying at different frequencies); LED stripe desklight is steady; fluorescent room ceiling light (has electronic ballast) is steady; the hallway light uses LED replacement lights for small halogen bulbs and flickers madly.
(The old laptop display is kind of bad one, it sometimes flickers even visibly while it "warms up", and it shows a bit of rolling flickering also in the normal photo mode preview, whereas the hallway lights and the CCFL-backlight display look completely steady in that mode.)
Slow-motion / high frame rate video recording not only needs plenty of light, it should be non-flickering type, either daylight or lamps with electronics that are good enough to give steady non-flickering light output. (Details, details: There are other means, but I don't think there is need to go into details here; photography/video forums/websites are better source of info at this point, as this applies to all cameras in general, not just mobile phones or specifically Note 9. Also, even normal photography should use non-flickering types of light, otherwise auto-exposure measurement just before the shot can get different light level than what ends up recorded on the sensor, possibly leading to bad and/or varying exposures, or even lighter/darker stripes on the photo if the exposure uses rolling shutter.)
The super-slowmotion preview is a nice way to check your lights, although it doesn't necessarily reveal all the problems. Normal camera with fast rolling shutter might be even better "detector" in this sense.
6thtry said:
These days the modern lamps can have all kinds of flicker frequencies and effects, especially at higher frequencies, due to using (cheap and/or small space) electronics to convert and control the mains voltage to the lamp's voltage/current, and the conversion has its own higher frequency.
The end result can still be flickering, just that it can also look different than the older 50/60Hz effect, depending on how the camera works. For example, it can show as lighter and darker stripes instead of brightness changes in whole frames.
For examples as seen right at my desk with preview: LED backlight display of my slightly old work laptop flickers wildly and full display effect; my newest LED backlight 4K monitor is steady; my older CCFL-backlight monitor shows a slow slightly colored rolling wave effect through a rainbow of shades; LED stripe desklight is steady; fluorescent room ceiling light (has electronic ballast) is steady; the hallway light flickers madly (LED replacement lights for small halogen bulbs).
(The old laptop display is kind of bad one, it sometimes flickers even visibly while it "warms up", and it shows a bit of rolling flickering also in the normal photo mode preview, whereas the hallway lights and the CCFL-backlight display look completely steady in that mode.)
Slow-motion / high frame rate video recording not only needs plenty of light, it should be non-flickering type, either daylight or lamps with electronics that are good enough to give steady non-flickering light output. (Details, details: There are other means, but I don't think there is need to go into details here; photography/video forums/websites are better source of info at this point, as this applies to all cameras in general, not just mobile phones or specifically Note 9. Also, even normal photography should use non-flickering types of light, otherwise auto-exposure measurement just before the shot can get different light level than what ends up recorded on the sensor, possibly leading to bad and/or varying exposures, or even lighter/darker stripes on the photo if the exposure uses rolling shutter.)
The super-slowmotion preview is a nice way to check your lights, although it doesn't necessarily reveal all the problems. Normal camera with fast rolling shutter might be even better "detector" in this sense.
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true. i have seen some 'artificial' lights in super slow mo which appears to not flicker, even after taking the video. usually i check it first before taking a super slow mo video.
even in normal mode i can see some flickering on some laptop screens and monitors, and even the moving stripes sort of thing that doesnt go away even after tinkering with the shutter speed. so i guess its more dependant on the type of light, rather than shutter speed? (not implying shutter speed is not important in this regard)
thats a lot of information to swallow on me, but hey, not bad to learn something new.
ammar18 said:
even in normal mode i can see some flickering on some laptop screens and monitors, and even the moving stripes sort of thing that doesnt go away even after tinkering with the shutter speed. so i guess its more dependant on the type of light, rather than shutter speed? (not implying shutter speed is not important in this regard)
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The preview may use one shutter speed, even if the actual photo (or video) would be taken at another shutter speed. And how it looks depends on both the frequencies/effects on the light and the frequencies (and shutter type) of the camera and mode/parameters in use. (And there can be other differences in other cameras. E.g. DSLR's typically use one aperture when looking through viewfinder and adjust that aperture quickly when the photo is taken, then return it back to the "viewing" aperture. And that is why there can be a "DoF preview" button, which forces the desired aperture already during viewing. Ooops, again into details, photo/video websites are better for this.)
ammar18 said:
yes, it is normal if lights flash, especially at higher fps
the default option for the slow mo on the Note 9 is super slow mo, which is 720p at 960fps. it requires quite a considerable amount of natural light, as artificial light, or lamps flicker. to get the normal slow mo, go to your camera settings, edit camera modes, rear camera and check Slow Motion. that way you can get higher quality slow motion at a reduced frame rate which reduces flickering.
on the side note, when you use super slow mo, you can remove flickering by playing the video, press the three dots at the upper right corner, and tap on Remove Flickering.
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Hi, I understand what you explain, but the iphone 7 is also able to film Slo-mo video support for 1080p at 120 fps and 720p at 240 fps. As noted in 720p 9 but it does not have the blink of light and its slow motion has a good image quality unlike our samsung.
So if we need an extreme amount of light to slow down, they are available only in certain good light conditions! Which makes the option not very attractive unlike the slow-mo iphone.
krz_ayman said:
Hi, I understand what you explain, but the iphone 7 is also able to film Slo-mo video support for 1080p at 120 fps and 720p at 240 fps. As noted in 720p 9 but it does not have the blink of light and its slow motion has a good image quality unlike our samsung.
So if we need an extreme amount of light to slow down, they are available only in certain good light conditions! Which makes the option not very attractive unlike the slow-mo iphone.
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are you using super slow mo or slow motion in your Note 9's camera?
https://www.youtube.com/watch?v=XIHg5p1KBsY
In this video, the image is clear and there is no light except the object that is lit. I do the same test and everything is completely dark and the quality very mediocre.
ammar18 said:
yes, it is normal if lights flash, especially at higher fps
the default option for the slow mo on the Note 9 is super slow mo, which is 720p at 960fps. it requires quite a considerable amount of natural light, as artificial light, or lamps flicker. to get the normal slow mo, go to your camera settings, edit camera modes, rear camera and check Slow Motion. that way you can get higher quality slow motion at a reduced frame rate which reduces flickering.
on the side note, when you use super slow mo, you can remove flickering by playing the video, press the three dots at the upper right corner, and tap on Remove Flickering.
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ammar18 said:
are you using super slow mo or slow motion in your Note 9's camera?
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I use slow motion
krz_ayman said:
In this video, the image is clear and there is no light except the object that is lit. I do the same test and everything is completely dark and the quality very mediocre.
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what you see might look like there is no other visible light source, but actually it has lights from behind as you can see from the shadow. it can look like its dim because of its high frame rate.
ammar18 said:
what you see might look like there is no other visible light source, but actually it has lights from behind as you can see from the shadow. it can look like its dim because of its high frame rate.
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Ok the friend, so in fact everything is normal and this mode is used in certain light conditions.
Hi, I understand what you explain, but the iphone 7 is also able to film Slo-mo video support for 1080p at 120 fps and 720p at 240 fps. As noted in 720p 9 but it does not have the blink of light and its slow motion has a good image quality unlike our samsung.
So if we need an extreme amount of light to slow down, they are available only in certain good light conditions! Which makes the option not very attractive unlike the slow-mo iphone.
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Frame rate matters; 240fps (let alone 960fps) might e.g. reveal flickering that is not noticed at 120fps. Each camera could also use different shutter speeds (which is not always the same as 1s/fps). Also, for proper comparison, the compared cameras should be used in the same circumstances (same lamps, etc.)
Quality differences is another topic I'm not going to comment on. There can very well be some, just like with the different quality of photographs with different cameras.
The amount of light does not need to be "extreme", but again, the higher the frame rate, the less time there is to expose (=gather light for) each frame, so the brighter the light needs to be for equal results. Specifically, e.g. 240fps vs. 960fps is 4 times difference in the light needed (if shutter speeds are scaled by the same factor). Or compare normal 30fps to 960 fps, the amount of light might need to be 32 times higher. As an over-simplified example (and not specifically for this Note 9 case), assuming a case where a normal 80W room light would be just enough for a nice 30fps video (shutter speed at maximum to still get 30fps), that light would need to be improved to a whopping 2560W for "equal" exposure with super slow motion. There are other factors affecting it, usually one doesn't really need 2.5kW of light (e.g. I can do a super-slow motion video that only gets a bit on the dark side right at my desk, which has light levels perhaps between recommended "normal room" and "office" levels and corresponds to maybe 20-40W of fluorescent output above the desk - but was it really 960fps, I didn't check), but this discussion is moving towards the territory of general video/photography stuff, other websites are better for these.
The linked video example is obviously made in a studio or studio-like environment, by people who likely know at least a bit on what they are doing ("Slow Mo Guys TV"), so they likely do have appropriately suitable lights (and then some).
The little bit of slowmotion / superslowmotion videos that I have so far taken with Note 9 hasn't shown me anything that I would not have expected (be it flickering lights or result getting too dark etc.) The only things currently in my list of questions related to Note 9 slow motion are: "is the video length in normal slow motion mode limited", "was the very begin and end of one normal slow motion video at normal speed, and if so then why, or does it even matter" and "what was that talk about 480fps and/or 0.2sec snippets I read somewhere (perhaps slips from S9+ or something)".
So, one can always simply try if the slowmotion mode works in the circumstances or not - no need to ignore it in other than certain light conditions - though I would not bother to even try at night, dark street, dim/dark rooms etc. Sometimes the light levels are ok, sometimes they are just too low or the lights are too flickery, in which case one might look for better lighting, and/or move to better lighting (closer to light, daylight outside, another room). Sometimes its tough luck, with no possibility to do decent slow motion video. In some cases one might be able to use certain software to make it slow motion in post-processing (but it has also its own limits). All this is also better explained in photo/video websites.
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ammar18 said:
what you see might look like there is no other visible light source, but actually it has lights from behind as you can see from the shadow. it can look like its dim because of its high frame rate.
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To me, the apple basket snippet looked like multiple large diffused lights (or lights with many lamps/sources of light) (and/or reflecting diffusers) from "all" directions (except not from below and less from left); I can't see any shadows there, e.g. the handle only makes slight fuzzy darker area near it, looking like there is at least one light source somewhere up-right.
The dropping water seems to have only one smooth light to left, as reflected from the metal and drop surface, and the drops (when round) do not show anything from behind (or reflections from the front side).
The 3rd scene seems to have at least two not-so-well diffused 4-lamp sources (seen warped in reflections).
But all in all, well arranged lighting in each case (except the bee, where it is likely just the sunlight, no "arrangement" needed).
Hi, when I use the slow motion , the whole display starts to flicker, but still works. all the other camera modes are fine.
Is that software issue?
Keyvannn said:
Hi, when I use the slow motion , the whole display starts to flicker, but still works. all the other camera modes are fine.
Is that software issue?
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The display is flickering while recording, or the video when playing back? I just tried, I don't see any flickering while recording. But if it's in the recorded video, what kind of lighting are you in? I recently tried to take a slo-mo with my S20, and had significant flashing. It was at night, I figured it was due to the LED lighting flash rate being slowed down.
dscline said:
The display is flickering while recording, or the video when playing back? I just tried, I don't see any flickering while recording. But if it's in the recorded video, what kind of lighting are you in? I recently tried to take a slo-mo with my S20, and had significant flashing. It was at night, I figured it was due to the LED lighting flash rate being slowed down.
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Yes, i would suspect this. Unbeknownst to the average person, LED lights tend to flicker A LOT. They do this at a given harmonic of the line frequency. If you're in the US then the LED will flicker either at 60Hz or 120Hz. Most people can't see this at full speed as the light has a bit of persistence and we're geared to see smooth motion. But, when you slow it down you find that at 240Hz or 480Hz the video is now fast enough to catch the dark patches in between the pulses. So, the video seems to strobe. Not all LED bulbs will do this and those that do won't all do it the same. But, it's there, you just can't see it. Keep in mind when shooting video in other modes this could still happen. At 60Hz or 120Hz video even though it's full speed you are still potentially capturing some frames in between pulses. This could cause a sort of beat frequency to appear. So, if anyone is having that problem when trying to shoot video your options are 1: do it in the sunlight. The sun doesn't flicker. or 2. Get a constant light source. Fluorescent bulbs have greater persistence as do the old incandescent bulbs. Professional lighting will be consistent too. But, $4 LED bulbs are going to SUUUUCK for slow mo video.
Yes. You were right. The problem was the led bulb.
That was interesting.
Thanks guys