Post by GJUK on Mar 18, 2017 23:58:29 GMT -8
Consumers get drunk on numbers. We've been pre-programmed by electronics companies for decades to believe anything bigger is better. It's why some people unnecessarily replace their 18 megapixel camera with the newest, shiniest 23 megapixel version. Yes, clarity and picture quality are important, but in that example, unless you're printing out your images in huge formats, there's practically no difference between them.
Don't get me wrong, I'm a fan of 4K...and 5K, 6K, 8K. In fact, anything that moves us closer to the feeling of there being no resolution at all is a great thing. But there's a couple of problems. Ignoring for a second the debate about vinyl sounding better due it generating a true analogue waveform, Compact Discs were digital clones of the EQ'd Production Master. Indistinguishable from the 16Bit 44.1kHz Stereo Master Recording itself. Why? Because it was UNCOMPRESSED.
So, the first problem with 4K (whether it be UHD 4K at 3840 x 2160 or 'true' DCI 4K at 4096 x 2160) is that it requires compression. LOTS of compression. What's compression? Well, if you don't know, check out this comprehensive Explanation of Video Compression Techniques white paper.
Remember when DVDs blew us away by taking our effectively 0.16 megapixel analogue VHS life and supercharged it. The format of the future was here. With only 345,600 pixels in total (at 720 x 480 in the USA) DVD was essentially just over one third of a megapixel. UHD has 8,294,400 pixels (True 4K has 8,847,360). This represents twenty-five times more picture information than crummy old DVD with only six to ten times the throughput.
Look at it this way:
Now, to my main point. Given that 4k has around twenty-five times the picture information in every second, you might be forgiven for thinking that 4K resolutions enjoy twenty-five times the bandwidth, write speed and file sizes. Not so. Most flying 4K video generating devices can dedicate up to around 60 megabits of information per second to 4K footage. That's only SIX times that of DVD which was capable of 10 megabits per second. The better 'pro-sumer' quads can stretch up to 100 megabits per second, but currently only if recorded in H.265, not the more universally handled-in-post H.264. While the pixels are far smaller, and there are certainly way more of them, the picture is less faithfully reproduced on playback by a factor of nearly five. Technically, ignoring resolution alone, DVDs represent far better picture QUALITY (or fidelity) than 4K.
You're still reading? Wow, ok, then I should probably get onto my second, and most important point. None of the above pays any attention to one often neglected aspect...FRAME RATE.
If you've tried filming anything in 4K from your drone already, you will have no doubt have been disappointed by one thing. No, not the crushing disappointment caused by the inability for your potentially underpowered computer to play it back smoothly, but rather the jerky flickering you experience around the edges of your motion footage.
Most of the movies you've ever seen have been at 24 or 23.976) frames per second. NTSC TV flickered images at you at 30fps (albeit interlaced). Why didn't these look so 'flickery'? Well, the movies were shot with a degree of intentional motion blur in each frame when motion was involved. NTSC TV content was interlaced, effectively doubling the frame rate...and that's what I'm building towards.
Did you ever purchase a PC game based upon the incredible images portrayed on the back of the strangely oversized box? Yes, even with the best graphics card on the planet at any given time it seemed impossible to play the game with all of those textures and effects turned on since it chugged along at around 10 fps. Dialing down the quality allowed for far slicker gameplay. The magic number was often around 60fps and this rings true for your footage.
Do yourself a favour...next time you're 'up there', try switching your video settings to 1080P at 60fps. The advantages being that you balance the resolution, bandwidth, file size and playbackability (hey, I just made up a word!) AND you get to quash all that jittery flicker that distracts your ultimate audience from whatever you're trying to get them to focus on what's actually in the middle of your footage. This flickering is caused not just by the few number of frames per second, but more that back of these thirty frames has a daylight shutter speed in the thousandths of a second.
Here's a practical example. All shot on a Phantom 4 at 1080P/60. Whenever people see this for the first time, other than being smitten by the awesome vistas offered by East Sussex, they often remark at how 'clear' it is. But they're looking at something far lower than 4K resolution, but the 60 fos provides a slickness they're not used to witnessing.
Don't get me wrong. I'm far from anti-4K. But distributing your footage is always a balancing act. Invariably you'll be sharing your footage online, and probably on YouTube, which will compress your beloved footage even more.
The other trick would be to use an ND (Natural Density) filter to cut down on the amount of light getting into your 4K video to allow for a shutter speed nearer to a 60th of a second (or as close to double your frame rate you choose as possible). I'll be going into the various ND options later in the Essential Extras section later.
Don't get me wrong, I'm a fan of 4K...and 5K, 6K, 8K. In fact, anything that moves us closer to the feeling of there being no resolution at all is a great thing. But there's a couple of problems. Ignoring for a second the debate about vinyl sounding better due it generating a true analogue waveform, Compact Discs were digital clones of the EQ'd Production Master. Indistinguishable from the 16Bit 44.1kHz Stereo Master Recording itself. Why? Because it was UNCOMPRESSED.
So, the first problem with 4K (whether it be UHD 4K at 3840 x 2160 or 'true' DCI 4K at 4096 x 2160) is that it requires compression. LOTS of compression. What's compression? Well, if you don't know, check out this comprehensive Explanation of Video Compression Techniques white paper.
Remember when DVDs blew us away by taking our effectively 0.16 megapixel analogue VHS life and supercharged it. The format of the future was here. With only 345,600 pixels in total (at 720 x 480 in the USA) DVD was essentially just over one third of a megapixel. UHD has 8,294,400 pixels (True 4K has 8,847,360). This represents twenty-five times more picture information than crummy old DVD with only six to ten times the throughput.
Look at it this way:
Now, to my main point. Given that 4k has around twenty-five times the picture information in every second, you might be forgiven for thinking that 4K resolutions enjoy twenty-five times the bandwidth, write speed and file sizes. Not so. Most flying 4K video generating devices can dedicate up to around 60 megabits of information per second to 4K footage. That's only SIX times that of DVD which was capable of 10 megabits per second. The better 'pro-sumer' quads can stretch up to 100 megabits per second, but currently only if recorded in H.265, not the more universally handled-in-post H.264. While the pixels are far smaller, and there are certainly way more of them, the picture is less faithfully reproduced on playback by a factor of nearly five. Technically, ignoring resolution alone, DVDs represent far better picture QUALITY (or fidelity) than 4K.
You're still reading? Wow, ok, then I should probably get onto my second, and most important point. None of the above pays any attention to one often neglected aspect...FRAME RATE.
If you've tried filming anything in 4K from your drone already, you will have no doubt have been disappointed by one thing. No, not the crushing disappointment caused by the inability for your potentially underpowered computer to play it back smoothly, but rather the jerky flickering you experience around the edges of your motion footage.
Most of the movies you've ever seen have been at 24 or 23.976) frames per second. NTSC TV flickered images at you at 30fps (albeit interlaced). Why didn't these look so 'flickery'? Well, the movies were shot with a degree of intentional motion blur in each frame when motion was involved. NTSC TV content was interlaced, effectively doubling the frame rate...and that's what I'm building towards.
Did you ever purchase a PC game based upon the incredible images portrayed on the back of the strangely oversized box? Yes, even with the best graphics card on the planet at any given time it seemed impossible to play the game with all of those textures and effects turned on since it chugged along at around 10 fps. Dialing down the quality allowed for far slicker gameplay. The magic number was often around 60fps and this rings true for your footage.
Do yourself a favour...next time you're 'up there', try switching your video settings to 1080P at 60fps. The advantages being that you balance the resolution, bandwidth, file size and playbackability (hey, I just made up a word!) AND you get to quash all that jittery flicker that distracts your ultimate audience from whatever you're trying to get them to focus on what's actually in the middle of your footage. This flickering is caused not just by the few number of frames per second, but more that back of these thirty frames has a daylight shutter speed in the thousandths of a second.
Here's a practical example. All shot on a Phantom 4 at 1080P/60. Whenever people see this for the first time, other than being smitten by the awesome vistas offered by East Sussex, they often remark at how 'clear' it is. But they're looking at something far lower than 4K resolution, but the 60 fos provides a slickness they're not used to witnessing.
Don't get me wrong. I'm far from anti-4K. But distributing your footage is always a balancing act. Invariably you'll be sharing your footage online, and probably on YouTube, which will compress your beloved footage even more.
The other trick would be to use an ND (Natural Density) filter to cut down on the amount of light getting into your 4K video to allow for a shutter speed nearer to a 60th of a second (or as close to double your frame rate you choose as possible). I'll be going into the various ND options later in the Essential Extras section later.
