--- title: "What Is a Video Codec? Definition and Examples | RentAnOTT" description: "A codec is the method used to compress and decompress video. See the main streaming codecs, H.264, H.265, AV1 and VP9, and how to choose between them." url: "https://www.rentanott.com/glossary/codec" markdown_url: "https://www.rentanott.com/glossary/codec.md" category: "Streaming technology" updated: "2026-10-05" --- # What is a video codec? A codec is the algorithm used to compress video or audio for storage and delivery and to decompress it for playback. The name combines coder and decoder. The choice of codec determines how small a file is at a given quality and which devices can play it. ## The main video codecs in streaming - H.264 (AVC): plays on practically every device; the universal baseline - H.265 (HEVC): roughly 40% to 50% smaller than H.264 at the same quality; standard for 4K and HDR; well supported on televisions and Apple devices - VP9: Google's royalty-free codec, similar in efficiency to H.265; common in Chrome and on Android - AV1: royalty-free and roughly 30% more efficient than H.265; hardware support growing on newer devices ## Audio codecs - AAC: the standard for streaming audio, supported everywhere - Dolby Digital and Dolby Digital Plus: surround sound for films and television - Opus: efficient and royalty-free, used mainly with WebRTC and on the web ## Codec vs container A codec compresses the video. A container, such as MP4 or MKV, is the file format that holds the compressed video, audio and subtitles together. An MP4 file may contain H.264 or H.265; the extension alone does not tell you which. ## How to choose Three things pull against each other: compression efficiency, which lowers delivery cost; device support, which decides who can play it; and encoding cost, which rises steeply with newer codecs. Licensing terms differ too. The usual answer is more than one. Encode everything in H.264 so that it plays everywhere, and add a more efficient codec for 4K and for your most-watched titles, where the saving in delivery outweighs the extra encoding and storage. ## Codec on RentAnOTT RentAnOTT handles encoding for you, up to 1080p on Launch and up to 4K on Growth and Scale. The bitrate calculator shows how codec choice changes bitrate and file size. [Try the bitrate calculator](https://www.rentanott.com/tools/video-bitrate-calculator). ## Related terms - [H.264](https://www.rentanott.com/glossary/h264) — H.264, also called AVC (Advanced Video Coding), is the most widely supported video compression standard. Finalized in 2003, it plays on practically every phone, computer, television and browser in use, which makes it the baseline codec for streaming. - [H.265](https://www.rentanott.com/glossary/h265) — H.265, also called HEVC (High Efficiency Video Coding), is the successor to H.264. It delivers the same picture quality at roughly 40% to 50% lower bitrate and is the standard codec for 4K and HDR streaming. - [AV1](https://www.rentanott.com/glossary/av1) — AV1 (AOMedia Video 1) is an open, royalty-free video codec released in 2018 by the Alliance for Open Media, a group that includes major browser, chip and streaming companies. It compresses roughly 30% more efficiently than H.265 and about 50% more than H.264. - [Video encoding](https://www.rentanott.com/glossary/video-encoding) — Video encoding is compressing video with a codec, such as H.264, H.265 or AV1, so that it is small enough to store and stream. It removes detail the eye will not miss and describes each frame by how it differs from its neighbors. - [Bitrate](https://www.rentanott.com/glossary/bitrate) — Bitrate is the amount of data used to represent one second of video or audio, measured in kilobits or megabits per second (kbps or Mbps). A higher bitrate carries more detail and produces larger files and higher delivery costs. - [Transcoding](https://www.rentanott.com/glossary/transcoding) — Transcoding is converting a video from one encoded format into another. On a streaming platform it means taking an uploaded file or a live feed and producing the several resolutions and bitrates needed for adaptive playback on every device. - [4K streaming](https://www.rentanott.com/glossary/4k-streaming) — 4K streaming is delivering video at a resolution of 3840 × 2160 pixels, also called Ultra HD or UHD, which is four times the pixel count of Full HD. It is usually offered together with HDR and reserved for a premium tier. - [Bitrate ladder](https://www.rentanott.com/glossary/bitrate-ladder) — A bitrate ladder, or encoding ladder, is the list of versions a video is encoded into for adaptive streaming. Each rung pairs a resolution with a bitrate, and the player moves up and down the rungs as the viewer's connection changes. ## Further reading - [Matroska vs MP4](https://www.rentanott.com/blogs/matroska-vs-mp4) - [Streaming bandwidth cost calculator](https://www.rentanott.com/tools/streaming-bandwidth-cost-calculator) - [Pricing](https://www.rentanott.com/pricing) ## Frequently asked questions ### What does codec stand for? Coder-decoder, or compressor-decompressor. ### Which codec is best for streaming? H.264 for reach, since everything plays it. H.265 or AV1 where devices support them and the delivery saving justifies a second encode. ### Is MP4 a codec? No. MP4 is a container. The video inside it is compressed with a codec such as H.264. All 163 terms: [Streaming and OTT glossary](https://www.rentanott.com/glossary). ## Book a demo Tell RentAnOTT what you are launching. The team walks through the platform and maps the path to go-live around your catalog, markets and revenue model. Book a demo: https://www.rentanott.com/contact ## More from RentAnOTT - [Home](https://www.rentanott.com/index.md) — What RentAnOTT is, what every plan includes, and how launch works - [Features](https://www.rentanott.com/features.md) — Every core feature and optional add-on - [Pricing](https://www.rentanott.com/pricing.md) — Platform tiers, apps, add-ons, usage rates and example bills in INR and USD - [Free tools](https://www.rentanott.com/tools.md) — OTT app builder and calculators for streaming revenue, bandwidth, bitrate and pricing - [Insights](https://www.rentanott.com/blogs.md) — All streaming business articles - [Glossary](https://www.rentanott.com/glossary.md) — Definitions of streaming and OTT terms - [Book a demo](https://www.rentanott.com/contact.md) — Talk to RentAnOTT about your launch Full site in one file: https://www.rentanott.com/llms-full.txt