Simply compression means to take a big file and compress it and make it smaller. If you are filming in HD you end up with a big file size this takes up loads of storage and will take a long time to transfer. When you compress it, it can cut the file size significantly. This then will take up less storage and can be transferred faster.
There are two ways to compress a video Spatial compression also know as intraframe and Temporal compression which is also know as interframe. Intraframe is only applied to individual video frames it uses the same process as what is used in a picture. It compresses each still picture and lines them up to use in the video. Intraframe compressions works the same as interframe compression as it gives pixels instructions on what to do. It gives instructions out such as staying the same, rotating and changing colour. There are “I” frames “B” frames and “P” frames. B frames are predictions between the “I” and “P” frames and use a quarter less data as “I” frames. Bitrates are the amount of data being used every second. If a video has a low bitrate it will be low quality. If a video has high bitrates it will be high quality. So the higher the bitrate the better quality video you will get.
Image from: http://shaunwilsondesigns.com/wp-content/uploads/2012/11/encoding-video.png
Video compositing is a process of combining multiple layers of video with each other or visual/graphical elements. Like with a composite image where you add layer on layer it is that process but done with moving image.
Image from: http://www.haunteddimensions.raykeim.com/layerdiagram.jpg
Video compositing is used everywhere it is used in news when it gives you the latest news this is called lower thirds. It works the same as a composite image where you have the video in the back, then you have the coloured box over the top of that, then you have the text over the top of that.
Image from : https://i.ytimg.com/vi/q3GOjOCvZBA/maxresdefault.jpg
A more complicated video compositing is shown the design film festival by Sebastian Lange. At 15 seconds you can see that he has had to use multiple layers. Langue has started of with a background which is a very blurry video. He then has used a mask and put the video inside the A. He has then done the same thing with the R but has used layers and put the R in front of the A. He has then done this again with the T. He has then used another layer to put the text on . A good and interesting technique he has used is that when the text is moving when it comes off the R it changes colour so you can see it on the background he has done this by using mask again.
Some different techniques used in video compositing are-
Mask – These are attached to the layer.
Matte – These are independent of the layer.
Rotoscoping – Used to remove parts of the layer.
Green Screens/Blue Screens – Used for composting two images or videos together.
A simple way green screens are used are in weather forecast as they put a image behind her on to the green surface.
Image from: http://philgreg.tv/wp-content/uploads/2011/07/weather.jpg
People would want to use video compositing because it gives them the chance to work within layers and you are able to add effects. By doing this they are able to give the video a better look and feel.
According to the website “dummies” video compositing is “when you composite a scene in your digital video, you actually layer several different clips of video over each other to make a single image.” (http://www.dummies.com/photography/video/compositing-video/)
Resolution is the number of pixels that together make a image. The higher the resolution the better the quality of the image. In television and moving image, however, there are standardised resolutions that must be used. the reason for this is that there are different devices that have different screen sizes with different resolution so these standardised resolution have been made so that they can work on all screens, from TV screens to your mobile phone. These standardised screens stop the film from being stretched or squashed.
HD – 1920 x 1080
SD – 1024 x 576
4k – 3840 × 2160
Pixels need to be told what colour they need to be the, they use RGB ( red/green/blue) to do this, with the minimum value being 0 and the maximum being 255. The mix of values colours determines the final colour of the pixel. The higher the resolution the more pixels there will be so this will increase the file size.
People use different resolutions as their are multiple delivery platforms, when making a film you want to record in a higher resolution as it will be on a big screen, but filming in this resolution won’t work on a SD TV as the resolution sizes are different, so you have to film in a resolution to the platform you want to put it on, or resize the film to fit on to an SD screen. The problem with filming at the wrong resolution is that the video will have to stretch itself to fit the screen its on or if its too big to fit on the screen some of the image will be missing.
The benefit of working with a large resolution is that you will get a high quality video the drawback to this though is that the file size will be really big. The benefit of working with a smaller resolution is that you will have a low file size the drawback of smaller resolutions is that the quality of the video will be low. A small video would be beneficial if you are working on something meant for phones with a smaller screen. A large video would be beneficial if you are working on something that will be played in the cinema on a big screen.
“In motion pictures, television, and in computer video displays, the frame rate is the number of frames or images that are projected or displayed per second.” (http://searchnetworking.techtarget.com/definition/frame-rate ).
To put it simply frame rate is measured by how many frames per second there is. When working it is very important to know your frame rate as it can ruin a video, this is shown in the image below. As you can see when filming the car at 30fps the car was moving to fast for the camera to video it smoothly. At 60fps the camera is able to capture the car clearly as the more frames there is the more pictures it taking per second creating a smooth good quality video.
image from: http://www.vitac.com/blog/tag/different-frame-rates
- PAL = UK – 25fps
- NTSC = USA – 30 fps (29.97)
- Film everywhere – 24 fps / 48fps
- Animation – 24fps
The drawback of using more frames per second is that there will be more images resulting in a bigger file size. This is okay with small videos but when filming movies this becomes a real problem because it takes a significantly longer amount of time to transfer the file and store it, and when playing the video the computer can’t keep up with all the information so the video would stutter.
Aspect ratio is measured between the height and the width. Aspect ratio is important because if your video is a different aspect ratio to what the are area on the monitor is a few things can happen. If your aspect ratio is bigger then it won’t be able to fit on the screen so it makes it smaller which will squash the image and you will be left with black bars at the top, you can even be missing some of the video. If your aspect ratio is smaller the same process will happen and it will try to correct it and it will make the video large which stretches the video, you can also be left with black bars on the sides.
This is what happen to the video when you film at the the wrong ratio so it has to render the video.
Image from: https://i.ytimg.com/vi/FOdi7Yo9SNc/hqdefault.jpg
“Most televisions and computer monitors currently available have an aspect ratio of 16:9, which offers a perfect fit for high definition television shows. However, movies are usually filmed with a ratio of 21:9, which will result in black bars at the top and bottom of the picture when it is displayed on the average TV. To fix this, some manufacturers are producing televisions with a 21:9 aspect ratio. The table above shows the most common aspect ratios.”
The image below shows what happens when you put a different video with a different aspect ratio to what the TV is, which shows your left with them black bars.
Motion graphics is a video or animation that have been edited with text, audio and photography. They are used everywhere from TV adverts to high budget Hollywood movies. Motion graphics can be used in a multiple of ways, an easy way it is used is when watching the news and they have the persons name at the bottom, these are simple motion graphics feeding you information.
A more complicated way is in film title sequences, in these they give you information such as who is in it who directed it and what company produced it. Sometimes they also show you what is going to happen in the film , like in the title sequences of “Se7en”
Motion graphics can include graphics, photograph’s , music and CGI. These together make a motion graphic. They are used really well in music videos because it gives a visual element to go with the music.
They are also used in commercials and branding.
A good way people are using motion graphics are in videos where they are just relaying information to you. This is good because it gives a visual stimulus to what normally would be boring but now is more interesting.
Motion graphics can be created by using software’s, such as Adobe After Effects. This allows you to created frames, add effects and have layers. According the website alboardman “Motion graphics is a digital technique that combines pictures, words, sound and video. Examples of motion graphics abound online and in real life, from the credits in Hollywood motion pictures to keynote addresses.” They also said “Motion graphics combine the languages of film, animation and graphic design. Combining different creative elements like typography, illustration, logos, shapes and video. They are then animated or moved in a way that tells a story.”
( http://www.alboardman.com/what-is-motion-graphics/ )