HD Resolution Support For Legacy Analog Composite Video?

A widesreen LCD TV displaying a true widescreen SD 16:9 DTV channel of GMA Network connected from digital terrestrial television receiver (DTT) receiver using only composite video jack wire instead of component jack or HDMI port.

I often wondered why a resulting analog composite video signal connected through a widescreen TV set often create an "high-definition like, high quality detail state" content using a single RCA composite video jack and slot in spite it only supports 480i (NTSC) and 576i (PAL/SECAM), compared to RCA component video jack up to 720p and 1080i and HDMI up to 1080p and 2160p. While most TV broadcasters start transitioning from 4:3 to 16:9 video content of their TV channels as part of transition from analog to digital TV btoadcast, most DTV devices in the Philippine market only offer composite video output as a result for making affordable purchase for most low income consumers to connect through analog CRT TV or even low-cost LCD TV. Generating an HD video content produced by most TV networks to those platforms may not be an easy task. A legacy composite video holding an HD-based content may result to picture blur or fuzziness as well as missing out fine detail.

In overview, if you want to know about composite video signal as well as a process of sorting various scanning lines to make a full picture known as raster, you may click here in Wikipedia article or read an old textbook about analog television. In my viewpoint, a single set of composite video signal representing a single horizontal line on TV screen may carry a maximum of estimately 352 pixels. (For experts in electronics engineer, correct me if I'm wrong by leaving in the comments below if my thought or assumption may be subject to misinformation.) Of course, a possibility to support more digital video pixels in a single line in analog form may be likely or unlikely depending on the condition of an analog carrier frequency signal bandwidth; that is, 6 MHz for 480i or 8 MHz for 576i.

One of the basic method of supporting HD video content to a source analog composite video is the use of a specialized video signal multiplexing or synchronization. The full reliable, accurate, and contextual information on such technique remains unknown. But before performing this, the source composite video must set from default 4:3 to an anamorphic 16:9 (stretched) aspect ratio. This was only possible to apply for the current analog terrestrial TV broadcast.

But how about DTV broadcasting producing digital 720p or 1080i content to source digital 480i video transmission? Well, that's technically complicated to encode using native MPEG-2 or H.264 video codec. The only effective method to encode original HD video content to analog 480i or 576i composite video signal support is the use of MPEG-5 LCEVC. (See this fan sample illustration below.)

A sample diagram when a 1080p60 video with LCEVC is "synch-in" to analog 480i composite video output.

As shown above, a 1080p 60 fps digital video format is separated and encoded in multiple layers from a single base lower tier resolution of 44×80 pixels or 1/10 of original 240p wide video; to first residual 165×90 pixels or 3/8 of 240p; to second residual 426×240 pixels as reference composite video output; to third residual 720×405 pixels or 3/8 of 1080p; to fourth residual 1920×1080 pixels. Combining these five layers may be downmix to source analog composite video before beaming through high definition widescreen TV using A/V composite jack.

The benefit of LCEVC-based content is not only enhances video quality with fine detail support and minimal artifact but also reduces video data footprint, compared to native base video encoding that often generates fewer data footprint. Hence, for example, a 1080 p 60 fps video generating at 16 Mbps adaptive bit rate (ABR) in native H.264 video encoding is reduced to 8 Mbps ABR by LCEVC H.264.

Of course, a 50-50 chance to make a "finer" detail in analog composite video supporting HD video may be possible if a combined base and residual video layer of LCEVC-based content through every source video scanning lines might be capable to "generate more" finite analog signal plot per video lines (different to express to say "oscillating waveform" since it only applies to a finite number of sine wave cycles per second). The result may vary depending on the condition that supporting a given prescribed video resolution per line may be either exceeding in or maxing out (that is for example a maximum of 352 pixels per line may possibly support 1280 pixels from 720p format or retain a prescribed limit).

In closing, whether a native or LCEVC-based HD video encoding would be used for legacy composite video support, it's up on the opinion of expertise whether agree or disagree in my thoughts here in terms of technicality of presumed attempt.