When you watch a video online, rarely are you viewing the original footage. Online video, either streamed or downloaded, is encoded one of several video codecs as a way of reducing the file size and making transfer a faster, easier and less taxing process for hardware.

If you’re interested in live streaming or video production, knowing more about the most popular and widely used video encoding formats can help you deliver high-quality footage without the usual large file sizes or quality issues that can be a major problem online.

Below, we’ve listed the four most common online video formats, along with a brief description of each codec’s key advantages, disadvantages, and unique features.


Widely used online, MPEG-4 is one of the most common video formats available. MPEG-4 type encoding can be used to store both audio and video — most of the time, you’ll see it used as an option for video, with the file extension .mp4.

MP4 stands for “MPEG-4 Part 14.” As one of the oldest video containers out there, MPEG-4 has been widely used since the late 1990s. Because of its low file size, it’s a popular option for a video that needs to be downloaded before viewing, as well as online streaming video.

As well as its small file size, a key advantage of MPEG-4 is its compatibility. Almost every device and browser, from modern PCs and smartphones to aging hardware, will offer complete support for MP4 video.


AVI, or “audio video interleave,” is another old video file format. Developed in the early 1990s as a Windows video codec by Microsoft, AVI is one of the most widely viewed digital video options, with an almost defacto status for web video.

One interesting fact about AVI video is that it can be encoded using a variety of different video codecs. This means that while AVI itself is widely compatible, you might need to download an additional codec if you’re viewing an AVI video on an older computer.

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Like MPEG-4, AVI is so widely used that it’s viewable on almost any device. Most short, lower resolution online videos are saved in the AVI format, although you’ll also find many short videos saved as MP4 files.


Another highly versatile video codec, H.264 has grown massively in popularity over the past few years as video content on the web has switched from lower resolutions to full HD and, in the last two to three years, to 4K.

A major advantage of H.264 is that it’s extremely versatile. Videos encoded using H.264 can be lossy and small in size, or almost completely lossless. It’s also far more efficient, from a file size perspective than older video codecs such as MPEG-4.

If you want to minimize your video’s file size while preserving as much detail as possible, H.264 is a great option. It’s also a widely supported codec, with full support on almost every operating system for PCs and mobile devices.


High-Efficiency Video Coding (HEVC), also known as H.265 and MPEG-H Part 2, is a video compression standard, one of the several potential successors to the widely used AVC (H.264 or MPEG-4 Part 10). In comparison to AVC, HEVC offers double the data compression ratio at the same level of video quality or substantially improved video quality at the same bit rate. It supports resolutions up to 8192×4320, including 8K UHD.

In most ways, HEVC is an extension of the concepts in H.264/MPEG-4 AVC. Both work by comparing different parts of a frame of video to find areas that are redundant, both within a single frame as well as subsequent frames. These redundant areas are then replaced with a short description instead of the original pixels. The primary changes for HEVC include the expansion of the pattern comparison and difference-coding areas from 16×16 pixel to sizes up to 64×64, improved variable-block-size segmentation, improved “intra” prediction within the same picture, improved motion vector prediction and motion region merging, improved motion compensation filtering, and an additional filtering step called sample-adaptive offset filtering. Effective use of these improvements requires much more signal processing capability for compressing the video but has less impact on the amount of computation needed for decompression.


If you’re an Apple user, you’ll definitely recognize this file format. Introduced by Apple as part of QuickTime in the 1990s, MOV is a video format that’s widely used to compress video produced using Mac OS.

Apple has updated the MOV file format over the years, with the current QuickTime X offering a good mix of quality and compression. Because this format is designed by Apple for its range of devices and operating systems, it isn’t as widely used as AVI or MPEG-4.

Another reason for the lack of popularity of MOV files is their lack of compression. While most MOV files are of a reasonable file size, they still take up more space than equivalent video in AVI, MP4 or H.264 formats.

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