High definition video format—which was developed by Japanese state TV network NHK about 1960s—become a mainstream on both professional and consumers in today’s digital age, as standard definition format—which was still used digitally in low-end devices like DVD and camcorders—is now mandatory for the defunct analog TV broadcast. In spite of the fact that HD format has higher transfer bandwidth digitally compared to SD format with minimal bandwidth, most current electronic consumer products have often complied with a high-end video codec like H.264 having with either variable bit rate (VBR) or adaptive bit rate (ABR) used to reduce bandwidth while enhancing video quality. However, such technique was not enough to reduce bandwidth so much as half as the given default ones even when attempting to stream over conventional broadband Internet.
If current HD digital TV broadcast uses only interlaced DV scan (1080i), and even if current HD digital devices like camcorder and HD recording hardware device use progressive DV scan (1080p), there is another way as an alternative to these two DV scanning technique, known as “progressively interlace” scan for full HD format (1080pi). So what is the difference between the current 1080i and 1080p format and my own conceptualized 1080pi format?
In interlaced DV scan, a single horizontal line is scanned from the upper portion to lower portion of the screen. In progressive DV scan, on the other hand, it generates a lower quality in a single stage of an entire picture until it refines to an even higher quality at successive stage. And in “progressively interlaced” DV scan, a single horizontal line generates an unrefined quality in a single stage and even refine further to a higher quality in a succeeding stage, so therefore the process has repeated in succeeding lines until the DV display is completed at minimal loss.
The following figure below shows a block diagram of a simple circuitry of DV scanning conversion from 1080p to 1080pi format. Here a 1080p format passes through a “segregator” that segregates a 5-stage progressive scan, and then each of them passes through a separated DV imaging memory cache before encoding with a 5-core DV interlace scan. The finalization of each core was filtered before layering the first five stage of progressively interlaced scan.
The process may even converted back from 1080pi to 1080p format by using a circuitry structure similar to the first but the difference is that—in finalization—every segregated “progressively interlace” scan may require de-interlacing. But if the de-interlacing technique from 1080pi format could not be successful, then it may require 1080i format conversion instead.
As 1080i format would generate at a constant bit rate (CBR) of 20 Mbps and 1080p format would generate at either an adaptive bit rate (ABR) or a variable bit rate (VBR) of 10 Mbps, 1080pi format—according to my own thought but it was not based on actual, factual scientific or technological claims—would generate at about 5 Mbps in ABR coding technique. The frame rate of 1080pi format, as compared to 1080i and 1080p with a frame rate of 50 to 60 fps, would generate at about 150 effective frames per second because of higher refresh rate at about 300 Hz or about 60 Hz of every five-core scanning.
But in spite of its minimal data bandwidth of 5 Mbps, I convinced that the picture quality of 1080pi HD video format would likely become limited compared to 1080i and 1080p format. In order to generate high quality video, every digital hardware equipped with 1080pi encoder with its high-powered performance CPU and GPU must control the level of brightness, contrast, sharpness, color, and hue, as well as controlling data compression to prevent video artifact due to data losses (also known as lossy.)
I ever wish that my own concept in H.264 video codec would be compatible to an upcoming Philippine variant of ISDB-T DTTV broadcast as an alternative to 1080i format from Japanese variant since it uses only MPEG-2 video codec. And because of its minimal data bandwidth, 1080pi would fit to 8 subchannels per 6 MHz channel carrier of ISDB-Tp. But the factual claims would be given to the public in the future…