Compression and video format

Analogue to Digital

Analogue to Digital, good example is camera. Camera changed analogue to digital. Because the analogue scenes is saved in digital. Do you know film camera? This is good example about Analogue to Analogue.  However nowadays camera is digital. If you take a picture to use camera, Camera put real images. But camera has a big problem. They put high quality video such as 24fps or 29.97 fps. If you has 16G memory, maybe you don’t save lots of video. Because high quality video  has lots of size. So we compressed video. If we save uncompressed video, it would be 7GB per minute, 420GB per hour.

Codecs

Co means Encode. Dec means Decode. A codec should not be confused with a coding or compression format or standard. Codec is a format is a way of storing data while a codec is a program which can read or write such files. Codec help to be a compression. And If you play video, it is decoding. There a lots of video, so you should compress video.

  • ProRes
  • H.264

We can choose Codec. When capturing to a camera, we do not use H.264. Because it is not good quality. So we use a codec like ProRes. ProRes is Apple codec. Apple use this codec. It is very very good quality codec. H.264 is highly compressed and not designed for editing. H.264 is a camera and distribution codec. It’s highly compressed, it means that the files are small. So H.264 is normal codec for displaying video on screen.

If you use codec in browser, you should check what browser support codec.

When you are film maker, all at video has been encoding using codec. You can import and edit video to use this program.

  • After Effect
  • Final Cut Pro
  • Premiere
  • AVID

Video format

We should know difference between file format and codec. File format is video container. It means, file format include video, audio, metadata, and codec.  They contain like a box.

  • AVI – MS file format, terrible format.
  • MP4
  • MOV – apple by file format(quicktime)

AVI cannot contain H.264 codec. And MP4, MOV can contain H.264 codec. So MP4 and MOV are best file formats. As a result, file format contain everything.

Resolution

Resolution

You can see resolution easily. For example, If you see video for Youtube, you can choose quality. This is resolution. You can see picture too. If picture has good resolution, you can see very very tiny something.

So Resolution refers to the number of pixels or individual color dots in an image. A high resolution image has more dots, which allows it to display more detail. Resolution has many quality. 1080p is best quality of this resolution.

  • 240p (320*240)
  • 480p (720*480)
  • 720p (1280*720)
  • 1080p (1920*1080)

Big pixel is not good. Small pixel is good. You should remember.

This site is example about high resolution.

http://360gigapixels.com/tokyo-tower-panorama-photo/

Aspect Ratio

Aspect Ratio

This is aspect ratio example. Aspect ratio is the relative horizontal and vertical sizes. Ratio is same shape. However size is difference. Nowadays we have a lot of monitor or screen. They have a aspect ratio. For example, if a graphic has an aspect ratio of 2:1, it means that the width is twice as large as the height.

  • Standard TV Ratio – 4 : 3
  • Widescreen Ratio  – 16 : 9

Widescreen have a funny history.

Widescreen have a funny history. In US, before war, TV was not exist. At that time there was a lots of theater. So many people went to see movie. However, After war, TV was formed. So many people didn’t go to theater. Because they can see TV like a theater. So after 1960, Film company made widescreen.

<Ben hur>

This film is most of widescreen movie. You can see black bar in this picture. This means, ratio is not fit this screen.

Frame Rates

Frame Rates

In television, and in computer video displays, the frame rate is the number of frames or images that are projected or displayed per second(FPS). That means the smoothness of the video.

L0112_FrameRates

There are 60 fps and 24 fps in this picture.  You can see lots of frames. 60 fps is more many frame than 24 fps. This means, during one second, 60 fps is more smooth than 24 fps.

This is video. As big as the number is, the video is smooth. If you see this video, you can understand more easily.

framerrate

  • PAL( Phase Alternate Line ) is 25fps. This means, runs 25 progressive frames per second. PAL is used in Europe and China. First start was Germany broadcasting company. PAL has more better resolution than NTSC. Because PAL use more high bandwidth than NTSC.
  • NTSC( National television System Committe ) is 29.97fps. This is general world frame rate. Lots of country used NTSC style for example US, Canada, Japan. Korea use NTSC too. This is color TV style. FCC chose this style in 1954.
  • SECAM( sequential couleur a memoire) is 25fps too. SECAM made in France and Soviet Union.  This is different  between PAL and NTSC. SECAM has a big problem. Black and white TV never support SECAM reception.
  • In film, frame rates use 24fps. All movie use 24fps. However Hobbit film used 48fps. It is double frame rate. When people saw Hobbit movie, they felt “It is not good video, because I’m familiar with 24fps speed. It looks to smooth”.
  • CCTV use 3-5fps. If you see 3fps something, maybe you can feel stop stop stop. Not good. 5fps is more better than 3fps.

If you make a video, you can choose frame rates speed like this.

video-frame-rate