In the upper-right corner, an inset shows a close-up of a portion of the image that exhibits mosquito noise. Compression of video generally works by comparing two frames and recording the differences between them, one frame after another, until the end of the video.
This technique works well when the camera is fixed in place, or the objects in the frame are relatively stationary, but if there is a great deal of motion in the frame, the number of differences between frames can be so great that compression doesn't do any good. Motion compensation is a technique that looks for motion either of the camera or of objects in the frame of view and determines how many pixels the moving object has moved in each direction.
Then that shift is stored, along with a description of the pixels that have moved that can't be described just by that shift. In essence, the encoder finds the moving objects, then builds an internal frame of sorts that looks like the original but with all the objects translated to their new locations. In theory, this approximates the new frame's appearance.
Then, to finish the job, the remaining differences are found, then the set of object shifts and the set of pixel differences are stored in the data representing the new frame. This object that describes the shift and the pixel differences is called a residual frame. There are two general types of motion compensation: global motion compensation and block motion compensation. Global motion compensation generally adjusts for camera movements such as tracking, dolly movements, panning, tilting, rolling, and up and down movements.
Block motion compensation handles localized changes, looking for smaller sections of the image that can be encoded using motion compensation. These blocks are normally of a fixed size, in a grid, but there are forms of motion compensation that allow for variable block sizes, and even for blocks to overlap. There are, however, artifacts that can occur due to motion compensation.
These occur along block borders, in the form of sharp edges that produce false ringing and other edge effects. These are due to the mathematics involved in the coding of the residual frames, and can be easily noticed before being repaired by the next key frame.
In certain situations, it may be useful to reduce the video's dimensions in order to improve the final size of the video file. While the immediate loss of size or smoothness of playback may be a negative factor, careful decision-making can result in a good end result. If a p video is reduced to p prior to encoding, the resulting video can be much smaller while having much higher visual quality; even after scaling back up during playback, the result may be better than encoding the original video at full size and accepting the quality hit needed to meet your size requirements.
Similarly, you can remove frames from the video entirely and decrease the frame rate to compensate. This has two benefits: it makes the overall video smaller, and that smaller size allows motion compensation to accomplish even more for you.
For example, instead of computing motion differences for two frames that are two pixels apart due to inter-frame motion, skipping every other frame could lead to computing a difference that comes out to four pixels of movement. This lets the overall movement of the camera be represented by fewer residual frames. The absolute minimum frame rate that a video can be before its contents are no longer perceived as motion by the human eye is about 12 frames per second.
Less than that, and the video becomes a series of still images. Motion picture film is typically 24 frames per second, while standard definition television is about 30 frames per second slightly less, but close enough and high definition television is between 24 and 60 frames per second.
Anything from 24 FPS upward will generally be seen as satisfactorily smooth; 30 or 60 FPS is an ideal target, depending on your needs. It achieves higher data compression rates than VP9 and H. AV1 currently offers three profiles: main , high , and professional with increasing support for color depths and chroma subsampling.
In addition, a series of levels are specified, each defining limits on a range of attributes of the video. For example, AV1 level 2. It's worth noting, however, that at least for Firefox and Chrome, the levels are actually ignored at this time when performing software decoding, and the decoder just does the best it can to play the video given the settings provided.
For compatibility's sake going forward, however, you should stay within the limits of the level you choose. The primary drawback to AV1 at this time is that it is very new, and support is still in the process of being integrated into most browsers.
Additionally, encoders and decoders are still being optimized for performance, and hardware encoders and decoders are still mostly in development rather than production. For this reason, encoding a video into AV1 format takes a very long time, since all the work is done in software. For the time being, because of these factors, AV1 is not yet ready to be your first choice of video codec, but you should watch for it to be ready to use in the future.
Varies depending on the video's level; theoretical maximum reaches Mbps at level 6. See the AV1 specification's tables of levels , which describe the maximum resolutions and rates at each level.
It's a motion compensation based codec that is widely used today for all sorts of media, including broadcast television, RTP videoconferencing, and as the video codec for Blu-Ray discs. AVC is highly flexible, with a number of profiles with varying capabilities; for example, the Constrained Baseline Profile is designed for use in videoconferencing and mobile scenarios, using less bandwidth than the Main Profile which is used for standard definition digital TV in some regions or the High Profile used for Blu-Ray Disc video.
Most of the profiles use 8-bit color components and chroma subsampling; The High 10 Profile adds support for bit color, and advanced forms of High 10 add and chroma subsampling. AVC also has special features such as support for multiple views of the same scene Multiview Video Coding , which allows, among other things, the production of stereoscopic video.
AVC is a proprietary format, however, and numerous patents are owned by multiple parties regarding its technologies. While web browsers are not required to do so, some do. However, be aware of its licensing requirements before choosing to use AVC in your project! Firefox support for AVC is dependent upon the operating system's built-in or preinstalled codecs for AVC and its container in order to avoid patent concerns.
ITU's H. Despite being optimized for low-bandwidth networks, it is fairly CPU intensive and may not perform adequately on lower-end computers. Variations on H. However, no major browser has ever included H.
Certain media plugins have enabled support for H. Unlike most codecs, H. During encoding, a value is selected for BPPmaxKb, and then the video cannot exceed this value for each frame. The final bit rate will depend on this, the frame rate, the compression, and the chosen resolution and block format.
The only real reason to use H. To use H. Version 1 of H. Later versions may support additional resolutions. HEVC was designed to support efficient encoding and decoding of video in sizes including very high resolutions including 8K video , with a structure specifically designed to let software take advantage of modern processors. For example, each coding tree unit CTU —similar to the macroblock used in previous codecs—consists of a tree of luma values for each sample as well as a tree of chroma values for each chroma sample used in the same coding tree unit, as well as any required syntax elements.
This structure supports easy processing by multiple cores. An interesting feature of HEVC is that the main profile supports only 8 bit per component color with chroma subsampling. Also interesting is that video is handled specially. Instead of having the luma samples representing the image's pixels in grayscale and the Cb and Cr samples indicating how to alter the grays to create color pixels , the three channels are instead treated as three monochrome images, one for each color, which are then combined during rendering to produce a full-color image.
HEVC is a proprietary format and is covered by a number of patents. Be sure to review the latest license terms and requirements before making a decision on whether or not to use HEVC in your app or web site! Information below is provided for the major profiles. There are a number of other profiles available that are not included here. MP4V is essentially H. You almost certainly don't want to use this format, since it isn't supported in a meaningful way by any major browsers, and is quite obsolete.
Files of this type should have the extension. There are no active patents remaining in relation to MPEG-1 video, so it may be used free of any licensing concerns.
However, few web browsers support MPEG-1 video without the support of a plugin, and with plugin use deprecated in web browsers, these are generally no longer available. This makes MPEG-1 a poor choice for use in web sites and web applications. The goal was to allow MPEG-2 to compress standard definition television, so interlaced video is also supported. But when you factor in its processing power and cost, H.
Plus, the number of devices that can encode and decode H. It lends especially well to low-latency workflows. Google developed VP9 as a royalty-free, open-source alternative to H.
VP9 was released in , which puts it in the middle of the pack as far as age goes. For one, VP9 performs about the same as H. This makes it well suited for 4K video, especially when publishing to YouTube. Beyond that, VP9 ranks second only to H. Samsung, Sony, LG, Roku, and many other household names support it. Both are open-source, and both claim to be royalty-free although there is some doubt surrounding this. For the time being, VP9 is also a better alternative to AV1, since more devices support it.
VP9 is a more advanced and higher-quality compression technology than H. It generates smaller files than H. This makes it an ideal codec for high-resolution streaming. That said, only about 10 percent of encoded files take the form of H. Uncertainties about royalties have stifled adoption. The patent and royalty drama surrounding H. Industry leaders like Google, Microsoft, and Mozilla had no interest in adding support for the costly codec to Chrome, Edge, and Firefox.
One place where H. Frustrated about the royalties associated with H. The goal? Create an open-source, royalty-free alternative called AV1. While the codec has been finalized, this initiative to democratize high-quality video delivery and playback is still playing out. This is why Cisco joined AOMedia as a founding member, and why Cisco has invested in making AV1 both efficient and accessible to the internet community. AV1 touts itself as being 30 percent more efficient than H.
It will also take some time before AV1 hardware decoding capabilities are integrated on a mass scale. Even Apple devices lack support for the codec, despite the fact that Apple joined the Alliance back in January of It will take some time before AV1 hardware decoding capabilities are integrated on a mass scale. The AV1 codec also requires lengthy encoding times, and time is money. The use of these formats is only recommended if you need to support a legacy system that can only accept this type of file.
These files use the H. MPG file. Choosing the right video file format depends entirely on what you plan on using the video for. You should choose a format that achieves the quality of video you require, but nothing more.
Unnecessarily high-quality video files can be unwieldy to move, share, convert, and manage. In addition, how the video files will be viewed is important. Not all programs, browsers, and devices can open a specific video format. Consider a couple of scenarios:. In summary, the most common video file types are:.
There are certain times when it is best to use one file format over another, and often, you have to convert between file formats. Get started for free with Filestack today.
Skip to content. Sign Up Free Log In. All Posts. What is the difference between a video codec, video container, and a video file format? Video files are made of 2 parts: a codec and a container. Which file format is my video file?
Which video format is the smallest? Video File Formats. More information about video codecs. Check your inbox! Click on the button in the email body to verify your email address - if you can not find it, check your spam folder.
The 1 Communications System! Sitemap Privacy. Get it Free for 1 Year Pricing. What are codecs? The following is a list of Codecs that are in common use today:. Audio codecs:.
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