Learning about the technical concepts related to the broadcasting and video production industry is beneficial in many ways. For one, you will get acquainted with the necessary knowledge required to make informed decisions. Equally, understanding these concepts helps you stay educated about the industry lingo.
Consequently, there are two significant terminologies. They are usually compared against each other when making a choice. The terms are interlaced vs progressive video. In this article, we compare the key attributes that differentiate the two video standards.
Comparison of Interlaced vs Progressive Video Standards
The term ‘video standard’ in this context is used to refer to the technical characteristics of a video signal. This is different from ‘video format’ which represents the container formats in which video data is held. Let’s start with progressive video standards.
Progressive Video Standards
The following is everything you need to know about progressive video standards. It will prime you for the comparison as you will have a basis for reference.
The Definition of Progressive Video
Progressive video is essentially a method of video playback. However, it is more complicated than it sounds.
To understand video playback, you need to first learn about the transmission and broadcasting of video content. Video transmission is a technical process that is tied to variables like bandwidth, video quality, latency, and so on.
The other key ingredient of video playback is broadcasting. This refers to the means by which a video is distributed using a display like a TV screen. The source of the video sends a signal to a receiver, which then translates the encoded video. This video signal carries the video data in an encoded format.
It is during the broadcasting phase that we get the two methods by which video content is translated and displayed — interlaced and progressive video.
Progressive videos will have their frames displayed entirely. A video frame has what’s called a scan line. For progressive video, these lines are displayed sequentially. The effect created by this is a uniform video image display. This method of display is also called progressive scanning and it has an effect on the overall quality of the image displayed.
The Image Quality of Progressive Video
Delivering all the scan lines of a video frame one after the other has a significant impact on the video playback. You already know that a video is an illusion created by images in motion. The notion of a video is expounded further by the idea of a video frame.
The image quality in progressive scans is sharp and detailed. When the frames are displayed at once, the viewer will see a sharp image in motion. It eliminates a delay that causes flicker as you will see when discussing interlacing video. In other words, there is more fluidity which is due to the smooth formation of video frames.
Why Progressive Video Is Suitable for Modern Display echnologies
Modern displays have features that are suited for progressive scanning. These features include;
- High bandwidth
- High network latency
- High decoding and encoding speeds
- Compatibility with diverse video signals
On top of these, most modern displays like LED screens are used to display high-quality video. Progressive scanning is largely suited for displaying high-quality video since its features support the expected viewing experience of a high-quality video.
Interlaced Video Standards
The features and specifications of interlaced video standards are completely contrasting from those of progressive video. Let’s break it down by defining the concept.
The Definition of An Interlaced Video
While the scan lines of a progressive video emerge one after another in sequence, those of interlaced show in phases.
The scan lines in interlaced video frames are grouped into odd and even lines. Each group is assigned the corresponding numeral. That is, odd lines are assigned odd numbers and even are designated by even numbers. When the video is being broadcast on a display, the frames flicker since the scan lines are shown in an alternating manner.
What this means is that an odd line gets displayed first then followed by an even line. As a result, the movement creates a flickering effect which is known as interlacing. This type of video construction is applied primarily to analog displays.
Purpose of Interlaced Video
Unlike progressive scanning which applies to modern systems, interlaced scanning was preferred in yesteryears for several reasons. For one, back then, the encoding formats of video supported this type of scanning. Secondly, display systems and video signal processing was far less advanced compared to today.
Provided that barriers like processing power were prevailing, interlacing methods made more sense in order to ensure a satisfactory viewing experience. It also ensured the transmission was supported by the limited bandwidth that existed.
Regardless, interlaced video is not entirely a thing of the past. There exist less-advanced displays in the market. Additionally, there are digital videos encoded for interlaced scanning and the need to be viewed. That’s why the method is still in use. However, if an interlaced video causes something called the interlacing artifact.
Interlacing Artifacts
Interlaced scanning leads to a visible effect when viewing the video in a progressive scan display. This is what is called an interlaced artifact. It occurs in the form of an unpleasant flickering, tearing, or jerking motion that hinders the consistent motion of the frames making up the video.
Interlacing artifacts are a result of low frame rates, poor video quality, and incompatibility between a video and a display processor. You can however mitigate this setback using a process known as deintelacing.
The deinterlacing process
Deinterlacing is a process that is used to convert interlaced video to progressive to enable it to be viewed on a modern display system.
Although the end goal is one, the process can happen in various ways. Deinterlacing seeks to combine odd and even scan lines that exist in an interlaced video. It is performed using advanced algorithms to fill the video frames with new lines. Ultimately, this achieves a flicker-free motion which is synonymous with progressive video.
Deinterlacing process techniques
Prior to attempting the deinterlacing process, you need to decide which technique is most suitable depending on a few factors. These factors include; the quality of the video, the desired image quality, and available processing power.
The following are the common deinterlacing techniques;
- Blending. This is the simplest of the deinterlacing techniques. It works by combining the odd and even lines to create a progressive line. Technically, the algorithm uses the averages of adjacent pixels of the horizontal fields. Blending can result in some form of interlacing artifacts since it’s not quite effective.
- Bobbing. This method multiples a single line into two, thereby creating a progressive rather than alternating line. The process ends up breaking the vertical resolution of the created frame into two. Similarly, the technique is not flawless.
- Motion-adaptive interpolation. Out of the three, this technique is the most effective at converting interlaced to progressive video. A sophisticated algorithm analyzes the scan line’s motion to create a progressive scan. The interpolation generates new image pixels, that lead to high resolution.
Deinterlacing has helped video producers refine aged video files and adapt them to today’s viewing standards. But interlaced video is still relevant since this process is imperfect and some applications require interlaced scanning. Therefore, it’s pertinent to compare interlaced vs progressive videos to hight their strengths and weaknesses.
Interlaced vs Progressive Video: Features and Specifications
Each of these video standards has specific features that distinguish one from the other. It then makes sense to compare them side by side and highlight the specifications of each feature or component.
Bandwidth requirements
While bandwidth requirements depend on factors like frame rate, video resolution, and bit rate, the transmission method plays a key role.
- Interlaced video
The scan lines’ appearance in the interlaced video requires less bandwidth since they transmit alternately. Also, the alternating nature ensures a much more efficient data transmission due to its odd and even display approach. The bandwidth limitations in the past were sufficient for interlaced videos.
- Progressive video
Due to the high processing power requirements, high video quality, and advanced display technologies, progressive videos need more bandwidth. This combination of factors produces the need for hefty bandwidths. Progressive video scanning is suitable for high-resolution and bit-rate videos and modern display technologies.
Video frame rate specifications
Frame rate refers to the number of frames displayed per second. The higher the frame rate the smoother the motion. When comparing interlaced vs progressive video, it is important to look at the frame rate specifications for each. Note that frame rates are regulated by either the PAL or NTSC standards.
- Interlaced video
Generally, interlaced videos will use a lower frame rate. This is the primary reason for the interlacing artifacts. These rates could be as low as 30 frames per second (fps). Yet, they can go as low as 24 fps.
The reason for the low frame rate is the halving that exists due to the splitting of a video frame into even and odd lines. As you would expect, a low frame rate also contributes to slow refresh rates. In return, this causes the flickering motion.
- Progressive video
Video formatting of progressive videos has high and diverse frame rates. While the frame rate is a standalone element, it needs to consider other components that affect video playback. Such factors include the type of video and the desired viewing experience.
Video quality
The specifications of video quality with respect to the video standard used is an element that can be used to compare the two. In this context, video quality refers to the technical characteristics of a video. Let’s see how they compare.
- Interlaced video
The vertical resolution of an interlaced video is typically low. It represents the number of vertical lines on a display. If a display has a 1080 resolution, it will display 1080 lines of interlaced video. However, due to the flickering effect and skimpy encoding of interlaced videos, these videos are stuck with low-resolution displays.
- Progressive video
When compared, progressive has a superior resolution to interlaced video. This ensures that the vertical resolution on a display matches the high resolution of the video, thereby creating a sharp image rendering.
Progressive video quality averts the loss of details. This ends up facilitating a pleasant viewing experience and accurate representation of the encoded video data.
The number of scan lines
Scan lines are the number of horizontal lines in a particular display. Primarily, scan lines are associated with older-generation display technologies. This is because those displays had fewer pixels hence the lines were clearly visible when viewing video content. Still, scan lines are present in both conventional and modern displays.
- Interlaced video
Similar to frame rates, scan lines are guided by PAL and NTSC systems. Both interlaced and progressive videos have 480 and 576 in the NTSC and PAL systems, respectively.
In interlaced videos, these lines are displayed in an alternating manner, which causes a ghosting appearance of the image. These videos have a designated character “i” after the number of scan lines for description. A common designation is 480i.
- Progressive video
Scan lines in a progressive video are displayed sequentially. The formatting used in progressive videos is supported by most modern displays. Hence, the picture quality is clearer and smoother.
Additionally, modern displays manipulate the image pixels to ensure that the scan lines aren’t visible. Eventually, this processing creates a high-resolution image. The number of scan lines in a progressive video will be designated the character “p”. For instance, 1080p means there are 1080 lines in the display.
Frame-rate Flexibility
The frame rate of a video can be adjusted during production and post-production. It depends on your reason for the adjustment. Changing the frame rate of an interlaced video has a different effect than that of a progressive video.
- Interlaced Video
In most cases, interlaced videos have a fixed frame rate per second, usually capped at 30 fps. Unless a deinterlacing technique is applied, changing the native fps of an interlaced video might ruin its playback and visual quality.
- Progressive Video
On the other hand, progressive video has a high degree of flexibility in terms of frame rate modification. You can change the fps of a progressive video to a desired rate. Options available include 24 fps 30 fps, 60 fps, or higher.
The frame rate of a video can be lowered and increased. For instance, the frame rate of a progressive video shot with a high frame rate setting can be lowered without losing its quality. To elucidate, the modern encoding of progressive videos and the processors of modern displays work in tandem to ensure uniformity.
Compatibility with modern displays
It is essential to consider how the scanning method behaves with a modern display. This is because most use cases require modern displays. Here is how the two scanning methods method compare with respect to modern displays.
- Interlaced video
From the earlier definition, we saw that interlaced scanning rarely works well with modern displays, unless special modification methods are used. As such, they are stuck with conventional displays that are much more compatible. The compatibility issues result in poor visual effects.
- Progressive video
Modern displays are primarily engineered to handle progressive scan videos. This type of scanning harnesses the full potential of the capable processors that come fitted in modern display systems.
As display technologies continue to evolve, more video content producers continue switching to progressive video scanning methods. This has the ripple effect of phasing out interlaced video scanning in areas where high image quality is preferred.
Comparing the Advantages of Interlaced vs Progressive Video
Having understood how certain features impact interlaced and progressive videos, you can effortlessly figure out the advantages of each type of scan. These advantages will inform decision-making when choosing between the two methods.
Advantages of interlaced vs progressive videos
| Interlaced videos | Progressive videos |
| Lower bandwidth requirements | Higher image quality and clarity |
| Compatible with older display technologies | Better compatibility with modern displays |
| Lower production and transmission costs | Suitable for high-definition content |
| Perceived higher vertical resolution | Reduced interlacing artifacts |
| Well-established broadcast standards | Support flexible frame rates |
| Smoother motion on legacy devices | Flicker-free and smoother motion |
As evidenced here, each of the scanning methods has its strengths. This is important since it will come in handy when choosing a type based on applications.
Comparing the Disadvantages of Interlaced vs Progressive Video
While it might not seem like it, progressive has its flaws, the same way interlaced video scanning has its strengths. The following is a comparison of the disadvantages between interlaced and progressive video.
Disadvantages of interlaced vs progressive videos
| Interlaced videos | Progressive videos |
| Reduced image quality | More noticeable motion blur |
| Inconsistent motion portrayal | Increased storage space is needed |
| Introduces interlacing artifacts | Larger file size requirements |
| Not suitable for high-definition content | Increased storage space needed |
| Reduced detail and clarity | Compatibility issues in post-production |
| Challenges in editing and effects | Limited support on older devices |
Important to note that the disadvantages highlighted above are quite general. This means there might be more specific cons that exist based on use cases, conditions, and other applicable aspects.
How to Choose Between Interlaced vs Progressive Video
The choice between these two scanning methods can be arrived at by examining various influential factors. Let’s delve into these factors.
Factors to consider when choosing the type of video scan
These factors include;
- The type of video content. There are certain videos that require features that are exclusive to either interlaced or progressive videos. For instance, archived videos are usually encoded in interlaced formats. Thus, these types of videos will be viewed best in displays that support interlaced formats.
- Application or use case. It helps to consider the specific situation under which the video will be played. If you are looking to display promotional videos on a large video wall, it makes sense to have them encoded for progressive scanning.
- The display used. This factor is closely related to the use case aspect. This is because different types of displays support different types of scanning. Choosing based on this factor helps attain compatibility.
- Available processing power. The reality is that progressive videos require more processing power than interlaced videos. Therefore, it would not be practical to choose to encode a video in progressive format when it can’t be supported.
Other factors worth mentioning include cost and future-proofing. In terms of cost, progressive videos can be costly to handle as compared to interlaced. The notion of future-proofing implies considering long-term applications. In other words, choosing a method that will be relevant for years to come.
Conclusion
Several things became clear after comparing interlacing and progressive video scanning methods. For instance, there is a need to be deliberate when contemplating between the two types of scans.
If you are looking for a summary of the main points, here is the clincher. Both interlaced and progressive videos have what sets them apart. Their technical specifications are applicable to distinct scenarios and use cases. Consequently, following this guideline will guarantee the desired visual effect is achieved.
