What is Video Encoding? A Complete Guide for Beginners

Video encoding is the process of converting video data from one format to another. This typically involves compressing the video, reducing its file size while preserving as much quality as possible. It’s done using specific algorithms known as codecs, which take the raw video input and create a smaller, optimized output.

By compressing the data, encoding significantly reduces file sizes, making video content simpler to store, transmit, and stream online. This technology plays a vital role in enabling both real-time and on-demand video playback across a wide range of devices, including smartphones, tablets, and computers.

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Why is video encoding important for streaming and media quality?

Video encoding is crucial for several reasons:

• Efficiency in streaming: By compressing video files, encoding reduces the bandwidth required for streaming, which helps prevent buffering a major issue for many video service providers.
• Quality preservation: Despite the compression, video encoding aims to maintain the quality of the original content.
• Cost reduction: Smaller file sizes lead to lower storage requirements and costs, particularly when using Content Delivery Networks (CDNs).

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How video encoding works: Process and techniques explained

The video encoding process involves several key steps that transform raw footage into a compressed format suitable for distribution and playback. Here’s a simplified breakdown:

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Step-by-step video encoding process

Step 1: Video capture

Every video begins as raw footage, which can be recorded by a camera or generated by software. This raw footage is typically large and stored in a lossless format to maintain the highest quality. However, these files are impractical for sharing, necessitating the encoding process.

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Step 2: Choose your video codec

• The first step in the video encoding process is deciding which codec to use. Each codec has its pros and cons, and the choice largely depends on the purpose of the video.
• H.264: This codec is widely compatible and offers a good balance between file size and video quality. It's great for most platforms, especially for web-based content like YouTube.
• H.265 (HEVC): If you need a smaller file size for high-resolution videos (like 4K), H.265 is a good choice. It delivers better quality at a lower bit rate but may not be supported on all devices.
• AV1: Although it offers superior compression and quality compared to H.265, AV1 is still in the early adoption stage. Use it if you're targeting modern devices and platforms, and file size is a top priority.

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Step 3: Choose the right video resolution

The resolution of your video determines its clarity and detail. Common video resolutions include:

• 720p (HD) – Standard for most web videos.
• 1080p (Full HD) – Common for movies, YouTube videos, and online streaming.
• 1440p (2K) – Typically used for high-end content and gaming videos.
• 2160p (4K) – For ultra-high-definition (UHD) video, popular in professional filmmaking and high-end content distribution.

The resolution should be chosen based on the desired quality and the devices your audience will use to view the video. Higher resolutions result in larger file sizes, so always balance the video quality with file size limitations.

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Step 4: Set the bitrate

The bitrate determines the amount of data used to represent the video per second. It plays a major role in both the video quality and file size. A higher bitrate generally results in better video quality but at the cost of a larger file.

• Variable bitrate (VBR): Adjusts the bitrate dynamically based on the video’s complexity, offering a balance between quality and file size.
• Constant bitrate (CBR): Keeps the bitrate fixed throughout the video, which is useful for streaming scenarios where consistent bandwidth is required.

For example:

• 720p videos might use a bit rate of around 2,500 to 5,000 kbps.
• 1080p videos could use anywhere from 5,000 to 10,000 kbps.
• 4K videos typically require bitrates above 20,000 kbps.

Adjust the bitrate based on the resolution and target platform.

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Step 5: Set the frame rate

The frame rate is how many individual frames are displayed per second. Standard frame rates include:

• 24 fps – Common for film and cinematic videos.
• 30 fps – Standard for most web videos and television.
• 60 fps – Typically used for smooth motion in gaming videos, tutorials, or sports broadcasts.

If you're encoding a video for a film-like aesthetic, you may want to go with 24 fps. For smoother motion or fast-paced content, 60 fps may be more appropriate.

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Step 6: Encoding the video

1. Compression process: The raw video file is processed using the chosen codec (e.g., H.264, H.265).
2. File size reduction: The encoder reduces the file size by removing redundant or unnecessary data while maintaining visual quality.
3. Time-consuming: This step can take a significant amount of time, especially for high-resolution or lengthy videos.
4. Computing power: The process requires substantial computing power, particularly for high-definition videos.
5. Hardware acceleration: Professional encoders often use hardware acceleration to speed up the encoding process (e.g., GPU-based encoding).

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Step 7: Wrapping in a container

1. Container format: Once the video is encoded, it is wrapped into a container format (e.g., MP4, MKV).
2. Combining streams: The encoded video and audio streams, along with additional data like subtitles or chapters, are packaged together.
3. Simplifies distribution: The container makes it easier to distribute and store the video file as a single package.
4. Metadata: The container can also store metadata such as file information, language options, and more, for easy playback and management.

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Step 8: Delivery and playback

1. Distribution: The final video file is ready for distribution, whether it's uploaded to a streaming platform (e.g., YouTube, Vimeo) or stored on a server.
2. Device decoding: When a viewer accesses the video, their device decodes the file, using appropriate software or hardware.
3. Playback: The video is then played back on the viewer's device (e.g., smartphone, laptop, smart TV), allowing the user to watch the content.
4. Compatibility: The container format ensures that the video is compatible across different devices and platforms for smooth playback.

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Top video encoding techniques for better quality

To deliver high-quality video content, especially over constrained networks, advanced encoding techniques are essential. Here are three key methods used in modern video encoding:

1. Adaptive bitrate streaming (ABR)
   
   Adaptive bitrate streaming (ABR) is a technique that optimizes video playback by adjusting the quality of the video stream in real-time based on the viewer’s internet connection speed. This method is widely used by platforms like Netflix and YouTube to ensure smooth playback, even on slower networks.

• How it works: Multiple versions of the same video are encoded at different bitrates. The streaming server dynamically switches between these versions according to current network conditions, balancing quality, and performance to enhance the viewer experience.‍

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2. Multi-pass encoding
   
   Multi-pass encoding is an advanced method where the encoder processes the video multiple times for better bitrate allocation.

• First pass: During this initial pass, the encoder analyzes the content to identify areas with high motion or complex details.
• Second pass: In this pass, it uses the analysis from the first pass to allocate more or less bitrate to specific parts of the video. This results in improved overall quality without increasing the file size.

3. GPU acceleration
   
   Encoding can be computationally intensive, particularly for high-resolution videos. GPU acceleration significantly speeds up this process by utilizing Graphics Processing Units (GPUs) instead of relying solely on Central Processing Units (CPUs).
   
   Benefits:
   • ‍Faster encoding times: GPU encoding can reduce encoding times by a factor of 5 to 10 compared to CPU-only methods, allowing for quicker production and publication of content.‍
   • Parallel processing: GPUs excel at handling many tasks simultaneously, making them well-suited for video encoding where multiple data points need processing at once.

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Real-world applications

• Video transcoding: Many broadcasters use GPU-accelerated transcoding to deliver multiple live channels efficiently.
• Video editing software: Applications like Adobe Premiere Pro use GPU power to speed up rendering and export times, allowing editors to work more efficiently.

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Key components of video encoding: What you need to know

Video files consist of two main components: the video codec and the container.

• Video codec: This is the software that compresses and decompresses video files. It determines how the video data is encoded.
• Video container: This format wraps around the encoded video and can include audio tracks and subtitles. Examples include MP4, AVI, and MKV.

The codec ensures that the video can be efficiently compressed while the container allows for multiple types of media to be stored together.

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Factors influencing video encoding

Several factors affect how video encoding is performed:

• Storage capacity: The available space influences how much compression can be applied.
• Output quality: The desired quality level of the final product will dictate encoding settings.
• Compatibility: The need for videos to play across various platforms and devices requires careful consideration during encoding.

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An overview of video codec usage in VOD

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The data illustrates the current adoption ("In Production") and anticipated growth ("In Planning") for various video codecs used in VOD encoding.

From the chart, we can see that:

• H.264/AVC is the most widely used codec in production, but newer codecs like AV1 and H.266/VVC have significant planned adoption.
• H.265/HEVC also has substantial production use and some plans for further expansion.
• AV1 and H.266/VVC are codecs with low current usage but a relatively high interest for future implementation.
• VP9 has moderate usage in both production and planned stages, while MPEG5/EVC, VP8, and MPEG5/LCEVC have limited usage in production and planning.

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VMAF and PSNR: Evaluating video quality in encoding

When evaluating video quality, two important metrics are VMAF (Video Multimethod Assessment Fusion) and PSNR (Peak Signal-to-Noise Ratio). Here’s a simple explanation of each:

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VMAF (Video Multimethod Assessment Fusion)

VMAF is a video quality metric developed by Netflix to assess video quality in a way that mirrors human visual perception. By analyzing factors such as sharpness, contrast, and motion, VMAF provides a single score that reflects perceived video quality higher scores indicating better quality. Unlike traditional metrics, VMAF is designed to match the way audiences actually experience video content, making it an essential tool for streaming platforms aiming to optimize video delivery and enhance viewer experience.

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PSNR (Peak Signal-to-Noise Ratio)

PSNR is a common metric for assessing the quality of compressed images and videos by comparing the original video to its compressed version to gauge the extent of quality loss.

It calculates the ratio between the maximum possible signal strength (from the original video) and the noise (or distortion) introduced by compression, with the result expressed in decibels (dB). Higher PSNR values indicate better quality, as they signify less distortion. Although widely used for its simplicity, PSNR does not always align with perceived visual quality two videos can share similar PSNR scores yet appear noticeably different to viewers.

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Impact of video codecs on streaming quality

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This image shows how using a video codec can improve quality and reduce file size.

1. With codec: The left side shows a high-quality, clear image that was processed with a codec. The details are sharp, and the colors are accurate, thanks to the codec, which compresses the file size without losing much quality. Common codecs, like H.264 or H.265, make this possible by smartly compressing the data so it’s easier to store and stream.
2. Without codec: The right side shows what happens without a codec the image is low-quality and pixelated. It looks blocky and loses a lot of detail, with distorted colors. This shows how, without compression, raw or uncompressed data doesn’t hold up well when trying to fit into limited file sizes or streaming bandwidth.

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How FastPix transforms video encoding with advanced solutions

FastPix uses widely supported H.264 codec to encode high-quality rendition ladder to give seamless experience even at low bandwidth conditions. FastPix also supports encoding using the AV1 codec.

You can integrate FastPix APIs to get the best compression to quality ratio and a seamless streaming experience.

An example of how you can create a media asset by using a public URL is as shown below:

Request body:

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1POST https://v1.fastpix.io/on-demand
2{
3  "inputs": [
4    {
5      "type": "video",
6      "url": "https://static.fastpix.io/sample.mp4"
7    }
8  ],
9  "metadata": {
10    "key1": "value1"
11  },
12  "accessPolicy": "public",
13  "maxResolution": "1080p"
14}

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Response body:

1{
2  "success": true,
3  "data": {
4    "id": "68668d2b-ed4f-4b6d-9bd5-c746700accbb",
5    "trial": false,
6    "status": "created",
7    "createdAt": "2024-11-06T10:49:23.944864Z",
8    "updatedAt": "2024-11-06T10:49:23.944877Z",
9    "playbackIds": [
10      {
11        "id": "7e1d6fb9-65d6-4b89-bcd1-3d2732461ba5",
12        "accessPolicy": "public"
13      }
14    ],
15    "metadata": {
16      "key1": "value1"
17    },
18    "maxResolution": "1080p"
19  }
20}

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To stream your videos seamlessly, simply use the playback ID with the following stream URL: https://stream.fastpix.io/{playbackID}.m3u8 and enjoy a smooth viewing experience.

Conclusion

By compressing and optimizing video files, encoding not only makes storage and transmission more efficient but also ensures a smooth and enjoyable viewing experience for users, even under limited bandwidth conditions. It achieves this by balancing quality with file size, adapting to diverse devices, and delivering seamless playback across varying network speeds. Through careful codec selection, bitrate management, and advanced techniques, video encoding transforms raw footage into a format that is accessible, high-quality, and compatible with modern streaming requirements.

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