In Video Compression, Which Is More Important - Bitrate or Resolution? Which Has a Bigger Impact in the Output Video Quality?
A question that often pops up during discussions of video compression and processing is whether bitrate or resolution has the greatest impact on video quality output. This confusion is common because both factors can have a profound impact.
Let’s begin our discussion by first trying to understand what compression is.
Compression—What you need to know about it
Compression is the technique using which the total number of bits required to represent a video sequence or image can be reduced. Usually, video compression is done with the help of programs, using certain formulae or algorithms.
The most common algorithms used for compression are-
- Constant bitrate or CBR- Here, the bitrate stays the same, but the video quality deteriorates.
- Variable Bitrate or VBR- Here, there is no compromise on the quality of the video, body betrayed value changes.
- Capped Variable Bitrate or Capped VBR- The video quality stays intact, but the bitrate can fluctuate within a cap or limit.
These algorithms determine the most appropriate way to reduce the size of the data present in a video. By using certain algorithms such as H.265/ or H.264/AVC, raw video data can be squeezed to about 1000 times.
For real time streaming, the natural baseband bandwidth for HD content is 3 Gbps. However, with compression, the network video stream can be reduced to somewhere around 1 to 10 Mbps. As a result, videos can be easily streamed using standard networks. This proves immensely helpful not just for end users but also for content creators and OTT service providers.
We know that audio files are generally compressed for better resource utilization. However, video files also need compression if they want to use storage efficiently. Compressed files have surprisingly smaller file sizes. Compression is a widely used technique in this digital era when no user has the time for buffers or data for bulky video files.
What is bitrate—How does it impact video quality?
Bitrate indicates how compressed you want a video to be. The encoder will compress the video according to your preferred bit rate. But while doing so, it compromises on the quality of the video. The more compressed a video, the lower its quality.
While compressing a video, certain algorithms are used which help decide and use a bitrate value.
The following points are extremely important to keep in mind when we talk about bitrate-
- With increased bitrate, the quality of a video improves. But it doesn’t improve beyond a particular point, no matter how high the bitrate value is.
- When we talk about bits, we don’t mean bytes. They are two completely different things.
- The quality of a video doesn’t depend on bitrate alone; other factors like display size, frame rate and resolution are also extremely important.
- You can have different video qualities by using different codecs such as AV1, VP9, HEVC and H.264/AVC, even when the bitrate value used is the same.
Now let’s talk about the importance of bitrate in video quality.
Well, it’s important to understand how videos are compressed if you want to know how bitrate impacts video quality. Compression algorithms perform two basic functions while compressing videos—
- The algorithm converts the video from the pixel domain to the frequency domain with the help of DCT or Discrete Cosine Transform.
- Uses Quantization to remove frequencies in a manner that the loss of information is not prominent or perceivable by the human eye.
In simple words, video compression involves discarding some information from a video to preserve its quality. However, when a video is heavily compressed, the information it loses makes the loss of quality pretty visible. Videos that are not compressed do have a large file size but their quality is top-notch.
This is definitely a trade-off which, in video compression parlance, is known as the rate distortion trade off. A lower rate points at a compromised video quality, provided the resolution is kept intact.
But one thing that you need to note here is that a lower bitrate doesn’t always result in poorer quality videos.
For instance, cartoon videos don’t lose quality even when they are compressed. Wondering why? Well, in cartoon videos, the motion is lower. And since flat surfaces are not difficult to compress, encoders can compress cartoon videos without compromising on their quality even at lower bitrates.
So, we understand that the quality of the output depends primarily on the type of video that has undergone compression.
What is Resolution—How does it impact video quality?
One of the factors that determines the quality of a video is resolution. To put simply, it is the width by height of a frame in a video, measured in terms of pixels. There are many different ways to express the resolution of a video.
Sometimes, it is expressed in terms of its height. Examples— 720p or 1080 p.
At other times, the resolution is expressed both in terms of its width and height. Examples—1280×720 and 1920×1080.
360p, 480p, 720p and 1080p are some of the most popular resolution types that are in use today.
Resolution is an extremely important determinant of video quality as it directly impacts the viewing experience.
Video players generally scale themselves according to the size of the viewing device’s screen.
Meaning, if you send a 360p video to someone so they can view it on a 48-inch TV, the video player on their TV will adjust the video in such a way that it fits its window. However, it’s important to note that a 360p video that has been up-scaled to 1080p will naturally lose its quality.
Also, a user playing a UHD video on their smartphone will not be able to enjoy it much because of its compromised quality. After all, smartphones are not designed to support UHD resolution. So, it’s evident that resolution plays an important role in determining the quality of a video and ensuring a smooth viewing experience.
So, we are back to the original question: which one is more important—Bitrate or Resolution?
Both bitrate and resolution are important for the quality of a video and for live video streaming. But there are things that you need to keep in mind before you get your videos compressed.
The first and most important thing that you need is to understand your target market, your audience and their viewing conditions.
- What do you think your target audience’s bandwidth would be? To figure this out, consider the geographical location of your audience. While you can expect an urban population to have access to 24×7 high-speed Internet, you can’t have the same expectation for a rural audience.
- What kind of Internet connection your target audience is likely to be using— Are they using the cable Internet or their mobile data plans?
- What devices your target audience is most likely using— Are they viewing your streams on their mobile devices or larger screens such as smart TVs?
- What kind of content do you stream— Are you streaming sports and movies where there is a lot of action, or news videos where the action is usually low.
- Which is the video codec most suited for your needs — Will the devices used by your target audience be able to decode VP9, AV1, HEVC and H.264/AVC?
Another important aspect that you need to consider is the amount of time you have at hand. Videos that are allowed more time to undergo compression generally produce better quality outputs as they get all the time they need to apply various algorithms for compression. In case you have time constraints, you can lower the resolution of your video to use the available bitrate better and to subject it to a quick compression.
Hence, by raising the right questions and keeping certain important points in mind, you will be able to decide on the resolution and bitrate for a video in a highly efficient way.
Bitrate vs. Resolution— The final verdict
It’s easy to infer from the discussion above that resolution and bitrate are not the same. They represent two different aspects of a video file. However, both work in conjunction with one another and are equally important.
To make a high resolution video look good on viewers’ devices, you will need to use a higher bitrate. Bitrate refers to the file size and speed, while resolution refers only to file height and width in pixels.
To come up with the right quality for your streaming content, you will probably have to experiment with different bitrates and resolutions. However, it is important to properly configure your encoder to achieve desired compression results, regardless of whether you are using it for videos meant for live or on-demand streaming.
In case you need assistance in this regard, you can contact Mogi I/O. They can compress your videos using AI technology so you can stream them on your OTT platform without hiccups. They are open for booking, and you can schedule a demo here. Alternatively, you can check out their website https://www.mogiio.com/ for more information.
Mogi’s Superior Transcoding Technique
Mogi I/O (www.mogiio.com) is an AI enabled Video & Image Delivery SaaS that helps Content Platforms to Improve Customer Engagement by enabling Buffer free Streaming Experience for the user through a patented multi-CDN upstream architecture called Mogi Streaming Engine, Enhanced experience through quality enhancement and compression of up to 50% both during transcoding itself and Deeper user insights through Advanced Video Analytics.
Mogi’s solutions are available end-to-end (Video Transcoding + Video Player + Mogi Streaming Engine (Multi-CDN delivery) + DRM + Video Analytics) or you can use individual products from the entire suite like just the Video Transcoding. Mogi also provides white label end-to-end plug n play solutions for OTT and Edtech Platforms, with Web, Android and iOS apps as well as a dedicated CMS for OTT and LMS for EdTech.
One of the best individual products we have is our Transcoding Architecture, which in a unique cluster based process, does the transcoding within 30% of the content length. The transcoding architecture’s result includes a highly compressed video of up to 50% with no loss in quality, and if you choose quality enhancement, a 40% compression with enhanced video quality.
The pricing for Transcoding is very competitive as well, and along with it you get a highly compressed output with the same or higher quality. This means not only your contractual pricing is low due to competitive pricing, your bandwidth consumption reduces, and user experiences increases multifold. It’s a win win for all of us (Users, Clients, Mogi).
If you want to partner with us and access our products, reach out to susheel.srinivas@mogiio.com