Every video you watch online has been encoded, from the Netflix series that streams without a hitch to the corporate presentation that loads in seconds. None of that can happen without encoding, or reducing the video file to a size that can travel across the internet.
After all, a single minute of uncompressed 1080p footage can exceed 10GB, which makes storage, sharing, and live streaming impractical at any scale. Encoding solves that problem by converting raw footage into a compressed digital format. The result is an encoded video file that's small enough to deliver, but detailed enough to look sharp on any screen.
This article covers what video encoding is and how compression works. We’ll also talk about the most common codecs and formats, and look at some ways to achieve the best video quality with the smallest file sizes.
What does video encoding mean?
Encoding is the process of converting raw video into a compressed digital format that can be transmitted and played quickly. A video or streaming encoder analyzes the raw content frame by frame, and strips out data the human eye won't notice.
This produces a smaller, compressed video file, while preserving as much visual quality as the codec settings and bitrate allow. The bitrate controls how much data is retained per second of video. Higher bitrates preserve more detail; lower bitrates reduce file sizes further at the cost of some quality.
Why is video encoding necessary?
Raw video is a sequence of many frames, each storing full-color data for every pixel onscreen. Uncompressed videos quickly grow to enormous file sizes, making them impractical to store or stream at any scale.
Encoding compresses that data so videos can move more efficiently through every stage of delivery. You can transfer the files from your camera to a server to a video player, without overwhelming your storage or viewers’ playback devices.
How does video encoding work?
An encoder scans each frame of your video for patterns and redundancies, then applies compression algorithms to reduce the file size. Decoding reverses that process at playback, reconstructing the video so it displays correctly on the viewer's device.
Transcoding is sometimes confused with encoding, but the former takes an already-compressed video file and converts it from one format to another. For example, you might use transcoding to optimize a file for a specific channel or screen size. Most video platforms handle encoding, decoding, and transcoding automatically.
How is video compressed? Lossy vs. lossless encoding
Every compressed video is the product of one of two general approaches. Let’s take a quick look at both.
Lossy compression
Lossy compression reduces file size by permanently discarding data the human eye is unlikely to detect. The amount of quality lost depends on the bitrate used.
A codec analyzes each frame, then decides what to keep and what to discard, targeting redundant pixels and subtle details. Almost all streaming video uses this type of encoding — H.264, H.265, VP9, and AV1 are all lossy codecs.
Lossless compression
Lossless compression shrinks the file without discarding any data. When decoded, the video is a perfect reproduction of the original. File sizes are far larger than those produced by lossy encoding, making this approach impractical for streaming. Instead, it’s used in post-production workflows where preserving every detail of the source footage matters.
Modern codecs push compression further by using two techniques:
- Spatial compression, which encodes repeating patterns within a single frame as one instruction, rather than pixel-by-pixel details
- Temporal compression, which stores only what changes between frames instead of redrawing the entire image each time
4 common video encoding formats
The right video encoding format for your workflow depends on how you weigh compression efficiency against device compatibility and licensing cost. Here's how the four most widely used codecs compare.
1. H.264 (AVC)
H.264, also called advanced video coding (AVC), is the most widely supported codec. It delivers reliable compressed video across virtually every device, browser, and platform, making it the default choice for general streaming. Compression efficiency is lower than with newer codecs, though, which means larger file sizes.
2. H.265 (HEVC)
H.265, also known as high-efficiency video coding (HEVC), compresses files roughly twice as efficiently as H.264 at the same quality level. This lowers the bitrate needed for 4K and other high-resolution formats. The trade-offs are slower encoding, higher licensing costs, and uneven device support.
3. VP9
VP9 is a royalty-free codec developed by Google. It offers compression efficiency comparable to H.265 without licensing fees, and it has strong support across Chrome and Android devices. VP9 is a common video encoding format for YouTube and browser-based streaming, although support on iOS and some smart TV platforms is limited.
4. AV1
AV1 is an open-source, royalty-free codec that delivers better compression than both H.265 and VP9. That makes this option well-suited for high-volume streaming with manageable bandwidth costs. Device and browser support is growing but not yet universal, so most platforms run AV1 alongside H.264 as a fallback.
Best practices for balancing file size and video quality
Encoding video for web delivery means matching your settings to how and where your audience watches. Platform, device, and connection speed all affect which encoding and bitrate choices deliver the best results.
These best practices can help you find the right combination of settings:
- Match resolution and bitrate to your delivery platform: A 4K file served to mobile viewers on slow connections wastes bandwidth and causes buffering.
- Use adaptive bitrate streaming for multi-device delivery: This requires a video player that automatically serves the right versions of your files, depending on each viewer's connection speed and device.
- Choose your codec based on your audience and workflows: For most streaming video encoding workflows, H.264 is the safest default because it offers broad compatibility. H.265 and AV1 are worth considering when you want better compression efficiency, and you know your viewers' devices support those formats.
- Opt for constant-quality encoding: For file-based and on-demand video, constant-quality encoding usually produces better results than constant bitrate encoding. This method allocates more data where images really need it, producing better-looking compressed videos at smaller file sizes.
- Test before you publish: Run a short clip through your chosen settings, and check it on the devices your audience uses before committing to a full encode.
Optimize your videos with Vimeo →
How to make video encoding faster and easier
Manually configuring and encoding a video takes time and leaves room for error. But these approaches reduce complexity without cutting corners on quality:
- Upload to a platform that handles encoding automatically: Some modern video solutions like Vimeo can handle codec selection, bitrate optimization, and output renditions automatically.
- Start with the highest-quality source file you have: The better the source file is, the easier it will be to get great final outputs.
- Avoid re-encoding already compressed video: Each additional encoding pass discards more data and introduces compression artifacts. If you need to re-export, go back to the original camera file instead.
- Start with the presets in your editing software: Most video encoding software includes export presets for common delivery formats.
- Use GPU encoding for faster exports: If you're encoding locally, enabling hardware acceleration through your GPU can reduce export times considerably.
Simplify the video production process with Vimeo
The codec, bitrate, and compression settings you choose help determine how your videos look and perform across devices and connection speeds. But with so many options and variables, finding the right combination for each video is a time consuming process.
That's why Vimeo handles encoding automatically. Just upload your source file, and Vimeo will encode it for reliable playback across devices. You also get adaptive bitrate streaming that adjusts to each viewer's connection, high-resolution hosting, and a centralized Video Library for managing and distributing all your content.
Host your videos with Vimeo →
FAQ
Does encoding reduce video quality?
Encoding always involves tradeoffs, but with the right codec and bitrate settings, the quality loss should be imperceptible to viewers.
Should I encode videos myself, or use a video hosting platform?
If you're publishing at volume, a video hosting platform is the faster and more reliable option. Once you upload your video, a platform like Vimeo can handle encoding, renditions, and delivery automatically.
What’s the difference between H.264 and H.265 for video encoding?
H.265 compresses video roughly twice as efficiently as H.264 at equivalent quality. This reduces the bitrate needed for high-resolution delivery, while the downside is slower encoding and less consistent device support. H.264 remains the safer default codec for broad compatibility.
What are iframes, and why do they matter for streaming?
An iframe is a complete image stored within a video file, while subsequent frames only store what changed from the previous image. Video players can only start playback or seek to iframe positions, so iframe frequency affects both performance and compression efficiency.
