MPEG–4 is the most common streaming format, and it consists of many parts, of which only MPEG–4 Part II applies for video coding. While still widely used, it's often strictly for video encoding and is often used with one of the more popular packs mentioned below. Both codecs can decode the output of the other, as they are both built on the implementation of MPEG–4. XviD/DivXĭivX is a commercially sold codec, while XviD is an open-source utility that functions as an alternative to its commercial cousin. Understanding where each codec is used can help you determine which codec you should use for your project. As you scale the video resolution, you must preserve the aspect ratio.Īs you might expect, some codecs are more popular than others.
Aspect Ratio: 4:3 and 16:9 are the two most common aspect ratios. If you want to understand more about frame types and keyframes, check out our guide on keyframes for video editing. They play an important role in video compression and are of three types: I-frame (keyframe), P-frame, and B-frame. Frame Type: It describes the way picture data is structured in an MPEG stream or file. It is expressed in frames per second (FPS). Frame Rate: The frequency or rate at which consecutive images are displayed. Constant bitrate maintains a constant bitrate per segment, regardless of the complexity. Video codec movie#
For example, higher bitrate for action-packed scenes in a movie and a lower-bit rate for slow scenes.
VBR and CBR: Variable bitrate encoding varies the output bits over time. The higher the bits, the more the picture quality increase-but so does file size. Bitrate: The number of bites you're allowing the tool to describe each frame of the video. Some settings are global, i.e., similar from codec to codec or specific to an individual codec. The key when using lossy compression is to settle on the highest quality compression format for your intended use so that you walk the fine line between loss of quality and file size.īefore we dive into the formats, you should be aware of the parameters that will directly affect the quality of the finished video. However, do remember that quality degrades with a higher ratio of compression.įor example, an average Blu-ray disc can exceed 40 GB, and that sort of storage space would not only be expensive, but it'd make digital downloads and purchases inconvenient. While you certainly lose quality in audio, video, or both, compressing is all about making the best compromises possible without giving up on quality. When looking for manageable file sizes, lossy compression is the most viable method. Depending on the codec, this encoding occurs in one of two ways: lossy or lossless compression. But principally, you have to maintain the trade-off between image quality, file size, processor usage, and popularity. Knowing when and when not to use a codec is important throughout the process of post-production, compression, and final delivery of your content. There are dozens of different codecs, and each uses a different technology to encode and compress your video file. Codecs use algorithms to effectively shrink the audio or video file size and then decompress it for playback, editing, or when needed. It is an encoding tool that processes video and stores it in a stream of bytes. You could spend weeks studying technologies that are useful only for a smaller number of applications, so instead, we're going to focus our attention on what technologies you'll use for video encoding, understanding the trade-offs and playback needs.Ĭodec is an acronym that stands for compressor/decompressor or coder/decoder. So, how do you teach yourself the difference between dozens of codec and container options? The lines blur when you realize that most common codecs aren't exclusive and can use multiple compression technologies to get the job done. Understanding the difference between codecs and containers is simple, but the hard part is explaining each format.
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