For example, Motion-JPEG uses only intra-frame compression, encoding each frame as a separate JPEG image. Intra-frame compression is essentially still image compression applied to video, with each frame compressed without reference to any other. Lossy compression technologies use two types of compression, intra-frame and inter-frame compression. In other words, the more you compress, the more quality you lose. Lossy codecs have one immutable trade-off–the lower the data rate, the less the decompressed file looks (or sounds) like the original. In contrast to lossless codecs, lossy codecs produce a facsimile of the original file upon decompression, but not the original file.
There are some lossless video codecs, including the Apple Animation codec and Lagarith codec, but these can’t compress video to data rates low enough for streaming. Lossless codecs, like PKZIP or PNG, reproduce the same exact file as the original upon decompression. There are two kinds of codecs lossless, and lossy. There are codecs for data (PKZIP), still images (JPEG, GIF, PNG), audio (MP3, AAC) and video (Cinepak, MPEG-2, H.264, VP8). Codec BasicsĬodecs are compression technologies and have two components, an encoder to compress the files, and a decoder to decompress. Next we’ll examine how H.264 became the most widely used video codec today, and finish with a quick discussion of audio codecs. First we’ll cover the basics regarding how codecs work, then we’ll examine the different roles performed by various codecs. Though you probably know what a codec is, do you really know codecs? Certainly not as well as you will after reading this article. Many video producers also touch the DVD-ROM and Blu-ray markets, as well as broadcast, and codecs play a role there as well. From shooting video to editing to encoding our streaming media files for delivery, codecs are involved every step of the way. Executive SummaryĬodecs are the oxygen of the streaming media market no codecs, no streaming media. This is an installment in our ongoing series of " What Is.?" articles, designed to offer definitions, history, and context around significant terms and issues in the online video industry.
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