What is SD and how is it different from HD?

How often has it happened that when you stream content on Youtube, you are disappointed by pixelation and try to adjust the video quality to a superior one? Or you want to enjoy a video shot in 4K but a poor network ruins your plan and you are able to see an inferior-quality video?

The audience today wants sharper, finer video quality of video content at their fingertips. Around 56% of the video streaming users find the resolution of the video content to be an important factor – which means more than half of the audience is concerned about resolution.

But what are these terms that define video quality and resolutions? What is SD and what is HD? Out of SD vs HD which one is more suitable and where? This article helps you in understanding all this and more.

However, before we move on to discuss what is SD and what is HD, it would be useful to understand two terms, ‘Display Resolution’ and ‘Aspect Ratio’.

• Display Resolution refers to the number of pixels that are present in the video and they are usually referred to as width x height. For example, when you see resolution being described as 720 x 480, it is width and height. However, in general terms, pixels are usually described by their height. So to refer to display resolution 720 x 480, we can also simply call it 480p.  

Aspect Ratio describes the width and height in proportion to each other. For example, a 4:3 aspect ratio would mean that for every four inches wide, the image must be 3 inches in height.

Now let’s move on to resolutions.

What is SD?

SD or Standard Definition is characterized by the smaller 720 x 480 interlaced screen size, 4:3 aspect ratio, and 480 lines of vertical resolution. SDTV was created to establish a standard for digitizing analog TV. Today, it is used in digital TV broadcasts and home appliances like game consoles and DVD players.

With technological advances in the past two decades, SD has become a bit ‘dated’. Do you remember the early digital cameras and camcorders? They shot videos in standard definition and some TVs used this resolution. Digital content viewed in Standard Definition is usually not of high sharp quality and is often blurry.

But SD is not entirely out of the window. Imagine you’re in a location where there is limited network infrastructure. In such a scenario, streaming in standard definition becomes useful, especially if you’re watching something on your mobiles and do not want to drain your internet data. The image in SD resolution is much less defined but it still caters to efficient transmitting of the content. SD resolution is also suitable for placing advertisements on websites in small square spaces, where a high resolution isn’t really a prerequisite to get clicks.

What is HD?

HD means High Definition. The meaning of HD is that it is superior in quality and resolution than the standard definition. This format of high definition screen resolution was introduced in the early 2000s. The TVs, monitors, cameras, mobile phones now support HD resolution.

Within HD, there are several variants with different display resolution and types of scanning modes.

If we see in hindsight, HD brought significant improvements in clarity and detail, but the demand for better resolution continued to grow. This led to the development of UHD (Ultra High Definition), which offers four times the resolution of HD. As advancements continued, 4K technology emerged, providing even greater detail and sharper images, making it ideal for large screens and enhancing the viewing experience. The evolution didn't stop there—8K technology has now entered the scene, offering an astonishing level of detail than the resolution of HD.

The HD quality also depends on the types of scanning modes used: interlaced or progressive. In the interlaced scanning method, the screen is filled up with rows of pixels, odd and even. At any given time, either the odd rows will be displayed or the even rows. It is a technique to double the perceived frame rate, making the viewer believe it is a complete frame but in reality it is not. Whereas, progressive scanning method displays every line on the frame in sequence, making the video look smoother.

HD is being extensively used today for terrestrial broadcast, satellite broadcast, digital cameras, mobile phones, OTT streaming, digital cables and video games. Honestly, shooting videos in HD has never been easier!

What is the difference between HD and SD?

When you see the image below, it is evident that the first one has sharper, defined lines and is clearer of the two. The first image shows the resolution when played on an 1080p setting and the second image signifies the result when played at 720p setting.

When it comes to differences between HD and SD, it is based on two main things – the resolution or the video quality and the bandwidth both require. Since HD is superior in quality, has more pixels to display digital images sharply, it requires more bandwidth whereas SD has a display resolution of 480 pixels and hence requires less bandwidth. HD also makes use of both interlaced and progressive scanning methods whereas SD makes use of interlaced scanning method.

Choosing to watch content in SD or HD depends on various factors. Imagine sitting down with your family to watch a much-anticipated film on a big screen TV. Would the experience be enjoyable if the quality was pixelated? You'd likely opt for the best quality the OTT platform can offer. Now, consider a different scenario where you're traveling and watching a YouTube video on your mobile phone in a network-scarce area. In this case, YouTube might automatically lower the quality to 240p to prevent lag. So, what does SD mean in movies?

Essentially, for a richer viewing experience, you'd choose HD when you have a strong internet connection. However, if you're sharing a hostel room with two other people and using shared internet, watching films on a laptop, tablet, or mobile phone in SD might be a better option.

Livestreaming in HD

Apart from the on-demand content available on various OTT platforms and Youtube, you can also choose to livestream in HD. According to Market Research Future, the live streaming market will be worth over $247 billion by 2027. Therefore, it is not not difficult to understand the need for livestreaming in HD by various platforms.

Live streaming in good quality and with minimal delay becomes particularly important when it comes to sports events, live gaming, e-learning, news and government or corporate events which are viewed by a large virtual audience.

Confused between livestreaming in RTMP or SRT? Read on!

HD vs SD in multi-streaming

Multi-streaming is the ability of the video server to offer two or more types of video streams differing in resolution, frame rate and other properties to cater to different users. The purpose of multi-streaming is that it allows the end user to get a video stream which is according to their requirements of bandwidth demands, storage constraints and quality.

When it comes to game streaming, popular platforms include Kick, YouTube, and Twitch, with Facebook Live emerging as a fast-growing option for gamers. New streamers on these sites typically aim for a solid 720p resolution at 30 to 60 frames per second (fps). However, if your system can handle higher resolutions and you want to multistream, there are some considerations.

All these platforms support streaming at 1080p, but they limit bitrates. On Twitch, for instance, streaming at full HD may not be worthwhile until you achieve partner status, as quality settings are locked for newer streamers. Similarly, Facebook Live supports only resolutions like 1080p (Full HD), 720p (HD), and lower resolutions. Higher resolutions are not supported and their availability may depend on the device you're using to stream.

Wrapping up

With the rapid technological advancements, we now have Ultra HD and 4K display resolutions that offer four times more pixels than standard HD. Cameras that shoot in 4K or higher resolutions capture every nuance and fine detail, which was previously impossible with lower resolutions. Display screens designed to showcase 4K content ensure that these high-quality visuals are fully appreciated, providing viewers with an exceptional viewing experience. This advancement is transforming everything from entertainment and gaming to professional photography and videography, setting a new standard for visual quality.

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