Understanding video bandwidth for streaming

Delivering high-quality video isn't just about capturing stunning visuals, it's about ensuring smooth playback over the internet, regardless of network conditions. Video bandwidth, the amount of data required to transmit video, plays a crucial role in this.

Whether you're streaming a movie in 4K or attending a video call, understanding how to manage bandwidth is key to providing a seamless experience.

In this guide, we'll break down everything you need to know about video bandwidth, including how it's calculated, what factors influence it, and how developers can optimize it for different use cases.

From codecs to adaptive streaming, you'll discover the techniques to balance video quality and bandwidth efficiency, so your content always looks its best, no matter the connection speed.

What is video bandwidth?

Video bandwidth refers to the amount of data required to transmit video content over the internet. It is measured in bits per second (bps) and directly impacts the quality and performance of video streams. Higher-quality videos such as HD or 4K requires higher bandwidth to maintain smooth playback, while lower-quality videos demand less.

To project the bandwidth usage for HD videos over a fixed period of time, you need to consider several factors, including video resolution, frame rate, compression (codec), and bitrate. The bitrate determines how much data is transmitted per second, and it's typically expressed in kilobits per second (kbps) or megabits per second (Mbps).

• Low bitrate: Lower video quality but saves bandwidth.
• High bitrate: Higher quality but requires more bandwidth.

How to calculate bandwidth

The basic formula for bandwidth projection is:

Bandwidth=Bitrate×Time\text{Bandwidth} = \text{Bitrate} \times \text{Time}Bandwidth=Bitrate×Time

Where:

• Bitrate is the video bitrate in bits per second (bps).

• Time is the duration of the video stream in seconds.

Example 1: Bandwidth projection for a 720p HD video

Let’s assume a 720p HD video with a bitrate of 3 Mbps streamed for 1 hour (3600 seconds):

Bandwidth=3 Mbps×3600 seconds\text{Bandwidth} = 3 \, \text{Mbps} \times 3600 \, \text{seconds}Bandwidth=3Mbps×3600seconds Bandwidth=10,800 Mb=10.8 GB\text{Bandwidth} = 10,800 \, \text{Mb} = 10.8 \, \text{GB}Bandwidth=10,800Mb=10.8GB

So, a 720p video streamed at 3 Mbps for 1 hour will consume approximately 10.8 GB of data.

Example 2: Bandwidth projection for a 1080p full HD video

For a 1080p Full HD video with a bitrate of 5 Mbps streamed for 2 hours (7200 seconds):

Bandwidth=5 Mbps×7200 seconds\text{Bandwidth} = 5 \, \text{Mbps} \times 7200 \, \text{seconds}Bandwidth=5Mbps×7200seconds Bandwidth=36,000 Mb=36 GB\text{Bandwidth} = 36,000 \, \text{Mb} = 36 \, \text{GB}Bandwidth=36,000Mb=36GB

Thus, a 1080p video streamed at 5 Mbps for 2 hours will use approximately 36 GB of data.

Bandwidth=5 Mbps×7200 seconds\text{Bandwidth} = 5 \, \text{Mbps} \times 7200 \, \text{seconds}Bandwidth=5Mbps×7200seconds Bandwidth=36,000 Mb=36 GB\text{Bandwidth} = 36,000 \, \text{Mb} = 36 \, \text{GB}Bandwidth=36,000Mb=36GB

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How to calculate video size given framerate, resolution and colour encoding per pixel?

To calculate the size of a video file given the frame rate, resolution, and color encoding per pixel, you need to follow these steps:

Formula for video size calculation:

Video Size (in bits)=Frame Size×Frame Rate×Duration (in seconds)\text{Video Size (in bits)} = \text{Frame Size} \times \text{Frame Rate} \times \text{Duration (in seconds)}Video Size (in bits)=Frame Size×Frame Rate×Duration (in seconds)

Where:

• Frame size (in bits) = Width (in pixels) × Height (in pixels) × Color Depth (bits per pixel)
• Frame rate (in frames per second) is how many frames are displayed every second.
• Duration (in seconds) is the length of the video.

How to calculate frame size:

Frame Size (in bits) =

Width (in pixels)×Height (in pixels)×Color Depth (bits per pixel)\text{Width (in pixels)} \times \text{Height (in pixels)} \times \text{Color Depth (bits per pixel)}Width (in pixels)×Height (in pixels)×Color Depth (bits per pixel)

For example, for a resolution of 1920x1080 (Full HD) with a 24-bit color depth (8 bits per channel for RGB), the frame size is:

1920×1080×24=49,766,400 bits(≈5.95 MB)1920 \times 1080 \times 24 = 49,766,400 \text{ bits} \quad (\approx 5.95 \text{ MB})1920×1080×24=49,766,400 bits(≈5.95 MB)

Calculate total number of bits for the entire video: Now multiply the frame size by the frame rate and the duration of the video.

Frame rate: Number of frames per second (e.g., 30 fps).

Duration: Length of the video in seconds (e.g., a 60-second video).

For example, for a 30 fps video that is 60 seconds long:

Total Bits=

49,766,400×30×60=89,579,520,000 bits\text{Total Bits} = 49,766,400 \times 30 \times 60 = 89,579,520,000 \text{ bits}Total Bits=49,766,400×30×60=89,579,520,000 bits

Convert to bytes/MB/GB: To convert from bits to bytes, divide by 8:

Total Bytes=

89,579,520,0008=11,197,440,000 bytes(≈11.2 GB)\text{Total Bytes} = \frac{89,579,520,000}{8} = 11,197,440,000 \text{ bytes} \quad (\approx 11.2 \text{ GB})Total Bytes=889,579,520,000=11,197,440,000 bytes(≈11.2 GB)

Example calculation:

Let's summarize using a specific example:

• Resolution: 1920x1080
• Frame rate: 30 fps
• Colour depth: 24 bits (8 bits per channel, RGB)
• Duration: 60 seconds

1. Frame size =

1920×1080×24=49,766,400 bits1920 \times 1080 \times 24 = 49,766,400 \text{ bits}1920×1080×24=49,766,400 bits

2. Total bits =

49,766,400×30×60=89,579,520,000 bits49,766,400 \times 30 \times 60 = 89,579,520,000 \text{ bits}49,766,400×30×60=89,579,520,000 bits

3. Total bytes =

11,197,440,000 bytes=11.2 GB11,197,440,000 \text{ bytes} = 11.2 \text{ GB}11,197,440,000 bytes=11.2 GB‍

Calculating the size of a video file involves determining the frame size, factoring in the frame rate, and multiplying it by the video’s duration. By using the video resolution, color depth, and frame rate, you can easily estimate the total size of the video in bits, then convert it into bytes or gigabytes for practical use. This method provides a clear understanding of how different factors contribute to a video's overall file size.

Factors affecting video bandwidth

Several technical factors influence how much bandwidth a video will consume. Let’s break down the most critical ones:

1. Resolution

Resolution is the number of pixels displayed in a video. The higher the resolution (e.g., 1080p, 4K), the more data is required to deliver that quality. Here’s a quick comparison:

• 720p (HD): Requires roughly 1.5-3 Mbps

• 1080p (Full HD): Requires around 5-8 Mbps

• 4K (Ultra HD): Requires 15-25 Mbps

Developer tip: If your platform allows users to switch between resolutions, ensure you dynamically adjust bandwidth usage based on the user’s network capacity.

2. Frame rate

The frame rate (measured in frames per second, or fps) defines how many frames are shown per second in a video. A higher frame rate (e.g., 60 fps vs. 30 fps) provides smoother motion but increases the data required.

• Standard video: 24-30 fps

• High-frame-rate video: 60 fps (used in gaming, sports, etc.)

Developer tip: Use adaptive frame rates depending on the content. Fast-paced content like sports may need higher frame rates, but regular video content may do fine at 24 or 30 fps.

3. Frame rate

Bitrate is the number of bits processed per unit of time and directly affects both the video’s quality and the bandwidth it consumes. It’s often the most significant factor determining how much data is required to stream a video. Bitrate is typically measured in kilobits per second (Kbps) or megabits per second (Mbps).

For example:

• Low quality (480p): Around 500 Kbps - 1 Mbps

• Medium quality (720p): Around 1.5 - 3 Mbps

• High quality (1080p): Around 5 - 8 Mbps

Developer tip: Use variable bitrate (VBR) encoding over constant bitrate (CBR). VBR dynamically adjusts the bitrate based on the complexity of the video, optimizing bandwidth usage without sacrificing quality.

4. Codec

The codec used to compress and decompress video files plays a crucial role in bandwidth consumption. Different codecs achieve various levels of compression efficiency, affecting file sizes and required bandwidth.

Popular codecs include:

• H.264/AVC: Widely used, especially for streaming and video calls. It offers a good balance between quality and file size.

• H.265/HEVC: Offers up to 50% better compression than H.264, making it ideal for high-quality 4K videos.

• VP9 and AV1: Open-source alternatives offering efficient compression and often used in web video (e.g., YouTube).

Developer tip: Choose the right codec for your project. While H.264 is most compatible with a wide range of devices, HEVC or AV1 can drastically reduce bandwidth needs for high-quality video streaming.

8K streaming bandwidth requirement

Streaming in 8K resolution, which offers ultra-high clarity at 7680 x 4320 pixels, requires a tremendous amount of bandwidth. Compared to lower resolutions like HD, Full HD (FHD), or even 4K, 8K has four times the pixel density of 4K, which means it holds far more visual information, such as texture, color accuracy, and overall detail.

Bandwidth needs for 8K streaming

To stream video, bandwidth is determined by both the video resolution and the efficiency of the video codec, which compresses and decompresses data. With 8K, these factors combine to require extremely high internet speeds for smooth playback. The typical codecs used for streaming, such as H.264 and H.265, are highly efficient but were not originally designed with 8K in mind.

1. H.264 codec: Widely used but less efficient for ultra-high resolutions, requiring about 32 Mbps for 4K streaming. For 8K, the bandwidth could quadruple, potentially needing around 100-125 Mbps or higher.
2. H.265 codec: Also called HEVC (High-Efficiency Video Coding), this codec provides better compression, meaning less bandwidth is needed. 4K streaming with H.265 might use around 15 Mbps, while 8K could require 50-60 Mbps.

Without newer codecs specifically designed for 8K (such as H.266, which is still emerging and not widely adopted), the data requirements stay high. H.266, if available, could cut bandwidth requirements by about half, making 8K streaming more feasible without maxing out typical home internet connections.

8K streaming on platforms

Platforms like Netflix, which offers 4K streaming at around 25 Mbps, would likely need a similar fourfold increase in bandwidth for 8K. Additionally, Netflix currently consumes about 7 GB per hour for 4K streaming, so an 8K stream could consume between 20-30 GB per hour depending on the frame rate and color depth, particularly for HDR (High Dynamic Range) content.

Comparison with 4K and 1080p

For perspective, 1080p (Full HD) streaming generally requires around 5-10 Mbps. Moving from 1080p to 4K (a jump in four times the data) results in an average requirement of 15-25 Mbps.

By the same logic, 8K would need quadruple the 4K bandwidth, possibly ranging from 60 Mbps up to 100+ Mbps depending on codec efficiency.

While 8K streaming offers unparalleled visual detail, it demands extremely fast and reliable internet connections, which are currently out of reach for many households. The adoption of newer codecs like H.266 will be essential to make 8K streaming more accessible.

Bandwidth optimization strategies

With the growing demand for high-quality video, developers must adopt strategies to optimize bandwidth usage while maintaining a good user experience. Here are a few ways to do this:

1. Adaptive Bitrate Streaming (ABR)

ABR allows video players to adjust video quality in real-time based on the viewer’s available internet bandwidth. It ensures smooth playback by reducing the video resolution or bitrate when the network is slow and increasing it when the network is fast.

• HLS (HTTP live streaming) and MPEG-DASH are popular protocols for ABR.

How ABR works:

• The video is encoded into multiple versions, each at a different bitrate and resolution (e.g., 360p, 480p, 720p, 1080p).

• The client-side video player continuously monitors the available bandwidth and switches between the different video streams (bitrates) based on the network conditions.

ffmpeg -i input.mp4 -b:v 1M -s 1280x720 -r 30 output_720p.mp4ffmpeg -i input.mp4 -b:v 500k -s 854x480 -r 30 output_480p.mp4

You can package these versions into an HLS or MPEG-DASH playlist, and the player will handle switching between them.

Developer tip: Implement ABR in your streaming applications to ensure the best possible quality at any given network condition.

2. Efficient video compression

Using advanced video codecs such as H.265 or AV1 helps reduce bandwidth without compromising video quality. These codecs offer better compression efficiency compared to older codecs like H.264.

Developer tip: Consider integrating these advanced codecs into your video pipeline, especially for high-resolution videos or large-scale streaming platforms.

3. Video transcoding

Video transcoding is the process of converting a video file from one format to another, typically to reduce the file size or optimize it for different devices or network conditions.

Developer tip: Use a cloud-based video transcoding service or build one with open-source tools like FFmpeg to handle multiple video resolutions, bitrates, and codecs.

4. Caching and CDN (Content Delivery Network)

A CDN helps reduce the load on servers and decrease the bandwidth needed for delivering videos by caching copies of the video content closer to the user.

Developer tip: Implement a CDN to store and distribute video content globally, reducing latency and optimizing bandwidth by reducing the load on your primary servers.

Use cases where bandwidth matters

1. Streaming platforms

For platforms like YouTube, Netflix, or Twitch, managing bandwidth is crucial for delivering high-quality videos to users across the globe. These platforms rely on ABR, efficient codecs, and CDNs to optimize bandwidth usage while maintaining an excellent user experience.

2. Video conferencing

In video conferencing applications like Zoom or Google Meet, ensuring low-latency, high-quality video with minimal bandwidth usage is critical. Developers must optimize bandwidth by balancing resolution, frame rates, and compression, especially for low-bandwidth connections.

3. Mobile applications

Mobile video applications need to consider both bandwidth and battery life. By using lower bitrates, resolutions, and efficient codecs, developers can offer a good experience even on slower mobile networks or limited data plans.

Final thoughts

Understanding video bandwidth is essential for optimizing the quality, performance, and cost-efficiency of any project involving video content. Whether it's streaming video, video conferencing, or building mobile video apps, balancing the factors like bitrate, resolution, frame rate, and codec choice can help you deliver smooth, high-quality videos even under varying network conditions.

With Fastpix, you can ensure that your video content reaches users in the most efficient way, no matter the platform or network conditions. Start leveraging these powerful video tools to streamline your next project.