Digital video is all around us. Whether it’s a disc, a streaming service, or a file on your computer, every video has a specific format. Understanding common video formats is essential for both people who make video and those who simply want to watch video.
Otherwise, you could be releasing poor quality content or you just don’t know why a certain video won’t play for you. In this article, we explain what video formats are, as well as the most common ones that everyone should know.
Format, container and codec: important concepts explained
The word “format” when applied to videos needs to be extracted a bit. In any medium, format is the standardized form. VHS and Betamax were home video tape formats. Although both used the same basic technology (TV signals recorded on magnetic tape), the exact method and design differed between the two.
The end result is that a VHS tape won’t work (or even fit) in a Betamax machine and vice versa. Digital video is no different. There are many different ways to encode video and audio as digital data. Thus, a player cannot understand or play a format for which it was not designed.
For a digital video, the size refers to the sum of all the bits and pieces that come together in the final video file. The first thing you see is the container. That is, whether the file is an .AVI. .MOV, .MP4 and so on. A container packs all the different elements of the video into a single file.
However, just because two video files have the same container doesn’t mean their sizes are exactly the same! Inside the container is the actual video data, audio data, and sometimes additional information such as subtitles.
Each of these has its own individual sizes. The video and audio streams each have their own unique formats, their “codecs†
The term codec is an abbreviation for “coder/decoder”. It describes exactly how video or audio is converted from its raw, uncompressed form to something of a more palatable size.
The common video format MP3 is an example of an audio codec. This allows high-quality CD audio to be reduced to less than a tenth of its original size without losing much, if any, subjective quality. Speaking of loss, now is a good time to explain “lossy” codecs.
“Lossy” vs. “Lossless” Formats
Video contains a lot of data. Analog film stocks, such as films made on film for most of their history, contain an incredible amount of detail. Therefore, it is possible to release HD, 4K and 8K remasters of old movies. All you need to do is go back and scan the higher resolution film frames. The detail is there, limited only by the resolution of the scanning equipment and the quality of the film grain itself.
There is a lot of information for a given image resolution. A single frame of 4K video equals a 3840×2160 photo! Compression technology uses several fancy mathematical ways to reduce the amount of information you need to reconstruct an image on the screen.
Most of these compression techniques are “lossy”. That is, they throw away some visual information to shrink the video data. However, the loss is usually very small and well worth the massive reduction in size. Any streaming video, DVD or BluRay content you view uses lossy compression.
Lossless compression for video is usually only found in master digital recordings for big budget movie projects or in movie archives.
Important Common Codecs
There are hundreds of different codecs, and in the past it was an absolute nightmare to install all the different codecs you might need to play video.
Worse, set-top players usually only supported a small number of codecs, so you’d need a computer to convert video into something those machines could understand. Today, almost all video is encoded with one of a small number of codecs.
H.264 – Advanced Video Coding
H.264 is by far the most popular video codec at the time of writing. With just over 90% of all video offered in this widely used video format. Because H.264 is so popular, most devices (such as smartphones and smart TVs) have built-in special hardware to decode H.264 video without straining the main processor of the device. Therefore even bottom-end smartphones can play HD video without breaking a sweat.
H.265 – The highly efficient video encoding
The High Efficiency Video Coding (HEVC) format of video compression has revolutionized video streaming as it can significantly reduce the bandwidth required. It was designed as the successor to H.264 and generally uses 25% to 50% less bandwidth to provide the same quality or better quality at the same bandwidth levels.
H.264 is enjoying great success in the streaming world, but unlike H.264, not many devices have dedicated hardware decoding components for this codec. So while it saves a lot of bandwidth and hard drive space, it will give the target device a real workout. As with H.264, this will likely change over time, but for now you should consider its limited support before choosing to use it.
MPEG-4 can get a little complicated. It is also a common video codec, but MPEG 4 Part 10 is basically the same as H.264. Early versions of MPEG-4 (eg Part 2) use older algorithms that are much less efficient in terms of space for the same level of quality. H.264 essentially replaced MPEG-4 with a new naming convention.
MP3 – MPEG Audio Layer-3
Almost everyone knows what a MP3 since it was the music format that rocked the record industry and eventually led to the digital streaming music and download model we all know today. What you may not know is that MP3 audio is also quite common in videos.
Since this format can squeeze CD-quality audio to about a tenth of its size without losing too much fidelity, it has been a mainstay of digital audio for years. Regardless of which video codec a particular video container uses, chances are the audio itself will be in MP3 format. Which also has different quality levels, with the golden mean usually falling around the level of 128 to 196 Kbps.
WAV – Waveform Audio Format
The “wave” format has been around for centuries and is (generally) an uncompressed digital audio file that accurately reproduces the original recording waveform. So, as you would expect, it takes up a huge amount of space. With the same quality settings as CD audio, a WAV file should take up about the same amount of space as a CD. While not particularly common, a video can also contain WAV audio.
Common video container formats
The final piece of the puzzle is common container sizes. This is what you will actually see as the file format of the video. In other words, the file extension you see belongs to the container. Let’s look at the most common.
The MP4 container format is supported by just about every device. It can contain any version in MPEG-4 format and H.264. YouTube videos are usually in this commonly used video format.
AVI – Audio Video Interleave
This is one of the oldest video containers and is not widely used anymore, but it is still widely supported and a lot of existing content is in AVI. The number of codecs that can be used in the AVI container is staggering, which is another reason why you would break a sweat trying to play an AVI file back in the good old days of the wild west of digital video. .
The MOV container is associated with the Apple Fast time Player and is the internal format. In a MOV file, you will most likely find MPEG-4 video data. Therefore, in most cases, you can rename a MOV file to an MP4 file and it will work exactly the same.
The main difference between MOV and MP4 files is that MOV files sometimes have copy protection. This prevents sharing and playing by unauthorized users.
Down The Video Format Rabbit Hole
These common video formats and containers are just the tip of the iceberg. DVDs, for example, use MPEG-2, but that’s rarely used now outside of the actual DVD discs you’d buy from a store. There are also professional video formats (eg ProRes RAW) and common formats traded on the Internet (eg MKV).
It would literally take an entire book to cover them all. However, the world is standardizing to H.264 and H.265. So if you’re making videos at any point, either one is probably a safe bet. With H.264 currently the safest of all!