You might see the word used when talking about audio codecs or video codecs.
Without codecs, downloads of video and audio would take three to five times longer than they do now.
How Many Codecs Do I Need?

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There are hundreds of codecs in use; you will need combinations that specifically play your files.
Some people who share their files on the web choose to use obscure codecs to shrink their files.
Instead, it is a container format that many different codecs can use.
Hundreds of codecs are compatible with AVI content.
How Do I Know Which Codec to Download and Install?
Because there are so many codec choices, codec packs are a convenient option.
Codec packs are collections of codecs gathered into single files.
Note this code and then visitFOURCCto obtain the missing codec.
FOURCC’sSamples pageoffers some FAQs if you need more information on what’s offered there.
Another option for getting codecs is to download media players that include them.
FAQ
A video codec is a piece of software that compresses and decompresses digital video.
Video codecs usually have four characters, such as MPEG, DivX, and HEVC.
Audio codec formats includeFLAC, WAV, ALAC, andOgg Vorbis.
The Xvid codec compresses and decompresses XVID files.