Evolution of TV standards

Television broadcast commenced approximately 55 years ago. NTSC, PAL and SECAM were the first analog TV standards used in America and Canada (NTSC), Western Union and Australia (PAL), and East Europe and France (SECAM). Without standards conversion, it is impossible to view a video program that is recorded in a foreign country without first converting it, because of the difference with the number of frames per second and the
number of scan lines, among other things.

TV standards have evolved over the years along with various options for including a colour burst to carry the colour as well as other features such as stereo sound and tilting. Terrestrial broadcasting has evolved from analog to digital. With larger screen sizes available in the marker, higher picture quality is desired, which motivated the standardization of the high-definition format. Nowadays, 3D is a trend, so there is flurry of 3D-TV standardization activity worldwide.

Analog TV standards

NTSC is used in USA, Canada, Mexico and Japan. It uses 525 scan lines and 50 fields/second (60 fields/second interlaced). An NTSC television channel as transmitted occupies a total bandwidth of 6 MHz with the color subcarrier at 3.56MHz.

PAL is used in Western Europe, Australia and some areas of Asia. It uses 625 scan lines and 25 fields/second (interlaced). The total bandwidth of a channel is 8MHz with and the color subcarrier at 4.43MHz. Related to NTSC, PAL has shorter run time because of the higher amount of fps.

SECAM is used particularly in France and Russia. It has technical similarities to PAL but nowadays it isn’t too used.

Digital TV standards

Standard-definition television (SDTV) uses a resolution of 720×576 with 720 pixels and 576 interlaced lines of resolution with 4:3 aspect ration. Each pixel is coded with 8 bits of resolution. The sampling structure of the digital picture is 4:2:2, which means the chrominance is horizontally subsampled by a factor of two relative to the chrominance.

High-definition television (HDTV) provides a higher resolution than SDTV. It has a resolution of 1920×1080 with 16:9 aspect ratio. It may be transmitted in various formats: 1080i, 720p, 1080p, Super Hi-Vision or DCI 4K.

Stereoscopic TV formats

The standard technique for 3D videos consists on two separated cameras at 6.5cm (horizontal), which is the distance between the eyes. It can be done with a single camera with two optical blocs.

Nowadays there aren’t any recording standards, so two duplicated and synchronized 2D formats are used.

3D TV formats

3D television conveys depth perception to the viewer by different techniques: color multiplexing, spatial multiplexing, temporal multiplexing or 2D+depth.

Color multiplexing uses color coding for L and R views. This format can be played in any 2D monitor but the video quality and 3D experience is poor.

Spatial multiplexing subsamples and compress L and R views from a 2D frame. The main advantage of this format is that it fits with existing infrastructure without increasing the bandwidth. However, the resolution is lower than the others.

Temporal multiplexing of L and R views incrementing the bitrate has the same resolution as the original video. Because of the higher bitrate, it needs a higher bandwidth, which is the main problem of this technique.

2D+depth transmits a 2D image with the depth map information associated. It is compatible with all 2D-devices (monitors and STBs) and codecs (MPEG-2 and AVC). However, two of the main problems are the high complexity of the format and the BER.


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