Digital video is combination of sequence of digital images, and they are made up of pixels or picture elements. Each pixel has two values, which is luminance and chrominance. Luminance is representing intensity of the pixel; on the other hand chrominance is representing the colour of the pixel. 3 bytes would be used to represent the colour of the high quality image for a true colour technique. A sequence of images is creating the digital video, in that case, images is called as frames. Movies are using 24 frames per second; however, the rate of the frames can change according to territories electrical system. So that there are different kinds of frame rates, for instance, North America is using approximately 30 frames per second where the Europe television frame rate is 25 frames per second. Each digital video has dimensions; width and height, when referred to analogue television, the dimension for SDTV is 650×480 pixels, on the other hand, numerous HDTV requires 1920×1080 pixels. Moreover, whilst for SDTV, 2 bytes (16 bits) is enough to create the colour depth, HDTV requires 3 (24 bits) bytes to create the colour depth. Thereby, with a rate of 30 FPS, the uncompressed date rate for SDTV becomes 30x640x480x16, in other words, 147,456,000 bit per second. Moreover, for HDTV, at the same frame rate, uncompressed date rate becomes 30x1920x1080x24 or 1,492,992,000 bits per second. With that simple calculation, it is obvious that without using a lossy compression methods service provider’s service delivery to the subscribers is limited.
Figure 9: Bandwidth capacity for simultaneously 2 HDTV stream, 2 SD stream, additional to HSD and Voice.
There is no absolute answer for the bandwidth requirement for the IPTV service because the bandwidth requirement is increasing due to the devices inside the household. Thus, currently compressed HDTV content can be delivered at a data rate between 8 to 10 Mbps, but if the home of the consumer equipped with several HDTV outputs, this rate will be multiplied respectively. The high speed data transfer will increase the needed bandwidth for the viewer, at least 2 Mbps needed to use web based applications on the computer. Additional to that, 64 kbps required to use landline telephone for the property. In minimal usage, to receive an IPTV triple play service requires 13 Mbps to process in the house.
