Why interlaced video

Techopedia Terms. Connect with us. Sign up. Term of the Day. Best of Techopedia weekly. News and Special Offers occasional. Interlaced Video. Techopedia Explains Interlaced Video. What Does Interlaced Video Mean? Interlaced video is also known as interlaced display. Techopedia Explains Interlaced Video Interlaced video is a procedure used for amplifying the anticipated frame rate of a video display without the need for additional bandwidth.

Synonyms Interlaced Display. Share this Term. This involves removing the added information from the frames to return it to the 24 frames per second. For example, frame 1 might be converted into frame 1A and frame 1B through interlacing, with each being a vertical odd or even sequence that is interlaced.

However, frame 2 might be converted into frame 2A, frame 2B and frame 2C, with the last one being duplicated content that is used to gradually increase the frame rate. As part of reverse telecine, this added content would be removed to restore the video to its original frame rate. Yes, if the source is not interlaced than the result can introduce needless artifacting if the deinterlacing methods are inadequate. This will be most noticeable on motion, which will have a greater loss of quality.

Fine, rounded details can also suffer, often converting a smooth look into a blocky look, like mini stairs as would be common in video games with pixels present and trying to create curves. If the type of deinterlacing being provided is blended, it can show obvious motion in the same frame. In addition, deinterlacing is more CPU intensive. So an encoder using deinterlacing will require to be on a better unit compared to a similar encoder not using deinterlacing.

So if a source is not interlaced, do not provide deinterlacing to it. After some sort of motion occurs in the feed it should be easy to tell if the source needs to be deinterlaced or not. Interlaced content displayed in a progressive manner is much more disruptive to the viewing experience compared to artifacts introduced from inadequate deinterlacing on already progressive content. For this reason, I personally recommend to deinterlace when dealing with mixed content. School of thought there can go both ways, though.

For example, if the amount of interlaced content is minimal, like briefly showing an older TV playing interlaced content, a broadcaster can get away without using it. Many modern broadcasters will never experience interlaced content when it comes to their own broadcasting. For example, someone using just a webcam and a software based encoder will never have to worry about this.

If you feel comfortable with the concept of deinterlacing, it might be time to get familiar with a streaming platform. IBM Watson Media. What is interlaced video? Progressive video and how it differs from interlaced video Which method is better: progressive or interlacing? What it looks like: interlaced content as progressive video How to tell if your camera captures interlaced video What is deinterlacing video: when you have to use interlaced sources How to deinterlace video for live streaming Another source of interlaced video: three-two pull down Reverse telecine: removing the pull down Can deinterlacing video be bad?

Progressive video and how it differs from interlaced video Unlike interlaced content, progressive video is a video track that consists of complete frames. This is true because the full resolution of an interlaced picture is only realized when it is a still picture.

The still picture is the best case; when the picture moves vertically between fields, vertical resolution is compromised. In the worst case, when there is vertical motion in the picture at a rate of an odd multiple of one scanning line per second, an entire field's worth of resolution is lost.

This line would move at a rate of two scan lines per frame, so that for the entire time it is in the scanned picture, it would always be located in either an odd-line field or an even-line field, depending on when it entered the scanned picture.

The line might, therefore, fall upon each successive scan line in the field that is being scanned when it arrives there. If so, it would appear to flash on and off at the frame rate as it travels through the picture.

It is also possible that it could fall upon each successive scan line in the field that is not being scanned when it arrives there. If this happens, it will move completely through the picture without ever being seen at all. The result of this in real television pictures is that the vertical resolution of interlaced pictures varies dynamically between nearly the line count of an entire frame and nearly the line count of a single field, depending on the degree and speed of the vertical motion components in their content.

In , a Bell Laboratories study concluded that the degree of resolution enhancement over the number of lines in a single field that was realized from interlaced scanning depends on picture brightness, but in pictures of normal brightness the enhancement typically amounts not to percent, but to 60 percent.

This is an interlace factor not a Kell factor -- Kell's research was done on progressively scanned images of 0. These findings agree with a previous study that was published in , and with the results of testing done by the Japanese broadcaster NHK in the early s. The NHK study concluded that the picture quality that may be achieved with interlacing is nearly equivalent to that achieved with progressive scanning, using only 60 percent of the scanning lines.

We note that tests conducted in the 50s, the 60s, and the 80s all produced virtually the same conclusion. Interlaced scanning was developed as a compromise to fit an adequate number of scanning lines and light flash repetitions into a signal of acceptable analog bandwidth. Different considerations apply in DTV, where the restriction is on digital bit-rate and the quality of digital compression, rather than on analog bandwidth.

This has led many to ask if interlaced scanning is still necessary in the world of DTV. TV Tech. Categories Opinions.

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