The structure of an electronic movie. The digital formats have many more options than the older analog formats.
Digital Video Formats
Following are the encoding variables in a digital video format. See
HD formats,
SD formats,
codec examples and
DTV.
Compression (DCT, MPEG, etc.)
The compression algorithm reduces the size of the video content by eliminating pixels, saving bandwidth and storage space. See
data compression.
Interframe vs. Intraframe
Interframe coding saves space by creating partial frames, which has implications when editing later on. See
interframe coding.
Chroma Subsampling and Bit Rate
Chroma subsampling saves space by compressing the color components, while the bit rate determines how much data can be encoded in each frame. See
chroma subsampling and
bit rate.
Resolution, Frame Rate and Progressive/Interlace
The horizontal and vertical resolution determines the aspect ratio of the frame and whether it is standard definition (SD) or high definition (HD), while the number of frames per second (frame rate) has impact on scenes with high-speed action. In progressive scan, there is twice as much information per frame as there is in the interlace method. See
screen resolution and
progressive scan.
Properties of Digital Formats
Following is a summary of digital video format attributes:
1 - compression (DCT, MPEG, etc.)
2 - interframe vs. intraframe
3 - chroma subsampling
4 - bit rate
5 - horizontal/vertical resolution
6 - frame rate
7 - progressive scan vs. interlace
Analog Video Formats
Following are the encoding variables in the analog NTSC, PAL and SECAM video formats. PAL and SECAM are still broadcast in some countries, and all of these formats still exist on VHS tapes. Modern digital TVs may provide one or more types of analog inputs to accommodate them. DVDs were on the market long before digital TVs were commonplace, and although encoded in the MPEG-2 digital format, DVDs conform to NTSC and PAL/SECAM resolutions and frame rates.
Resolution, Frame Rate and Interlace
NTSC, PAL and SECAM are interlaced standard definition (SD) formats. NTSC has 480 lines of resolution at 30 frames per second (fps), and PAL and SECAM have 576 lines at 25 fps. See
NTSC,
PAL,
SECAM and
interlace.
Component, S-Video and Composite
NTSC and PAL are mastered in the YUV color space, which requires three "component video" cables to carry the video signals (SECAM uses a variation of YUV). As the content is transferred to VHS tapes and other lower-quality destinations, colors are combined to save bandwidth, and only one cable is used. See
YUV,
component video,
S-video and
composite video.
Properties of Analog Formats
Following is a summary of analog video format attributes:
1 - horizontal/vertical resolution
2 - frame rate
3 - progressive scan vs. interlace
4 - component, S-video and composite