Where VP9 comes from
VP9 is a video codec developed by Google and released as a royalty-free format in 2013. Its roots go back to a company called On2 Technologies, which created the VP family of codecs. Google acquired On2 in 2010 and made the VP8 codec available as open source, alongside the WebM project, which defined a media file format built around open codecs (VP8 or VP9 for video, with Vorbis or Opus for audio).
VP8 was meant to give the web a freely usable alternative to H.264. It was adopted in some places but was generally considered less efficient than H.264, and its licensing position was debated at the time. VP9 was the follow-up, designed to compete on efficiency, especially at high resolutions.
How VP9 improves on VP8
VP9 follows the same general method as other modern codecs, based on block prediction. It divides pictures into blocks, predicts them from neighbouring or earlier data, transforms and quantises the differences, and compresses the result.
Key improvements over VP8 included:
- Larger blocks. Superblocks of up to 64 by 64 pixels, subdivided as needed, make high-resolution video cheaper to describe.
- More prediction and transform options. A wider range of block shapes and transform sizes lets the encoder match different kinds of detail.
- Better motion handling and reference frames. Improved ways of referring to earlier frames reduce the data spent on movement.
- Parallel-friendly design. Features such as tiles make it easier to split encoding and decoding across several cores, which helps at 4K.
These ideas are comparable to those in HEVC, which was developed around the same time. Comparisons between the two generally find them in a similar range, with results depending on the encoder, the content and the settings. Compared with H.264, VP9 is typically able to deliver similar quality at a noticeably lower bitrate, with the gain larger at high resolutions.
Licensing
The reason VP9 mattered beyond efficiency is licensing. Google published the specification and granted a royalty-free patent licence, so that anyone could implement it without paying fees. That made it appealing to browser developers and open-source projects. As with any codec, no one can give an absolute guarantee about every possible third-party patent claim, and legal outcomes vary by country. Still, VP9 was a significant step towards royalty-free video on the web and an influence on the later AV1 codec.
Where VP9 is used
VP9 became important on the web mainly through YouTube. Google’s video platform used VP9 to deliver higher-resolution versions of videos to browsers and devices that could play it, reducing the data needed for each view. Other services and applications also use it, and it appears in video conferencing and in some real-time communications, where WebRTC calls can negotiate it as one of the available codecs.
Support in browsers is broad, though the history was uneven:
- Chrome and other browsers based on the same engine were early supporters.
- Firefox also supports VP9 playback.
- Support in Apple’s Safari arrived later and has historically depended on the operating system version and device capabilities.
Because exact support differs by version and platform, anyone relying on it should check current compatibility information rather than assuming it.
VP9 video is commonly delivered in the WebM container, though it can appear in others. The codec compresses the pictures, while the wrapper, one of the container formats, holds the streams together.
Hardware support
For a codec to spread beyond computers, devices need hardware decoders. VP9 hardware decoding appeared in many chips for phones, televisions and set-top boxes over the years, which is why it became practical to use on mobile and in living rooms. Encoding support in hardware is less common than decoding support, so many VP9 files are created with software encoders, which can be slow at high quality.
Limitations
- Slower encoding. Compared with H.264, VP9 encoding generally requires more time or computing power to reach its efficiency.
- Uneven support in professional tools. Cameras, broadcast systems and some editing software favour H.264 and HEVC.
- Not universal on Apple devices. Gaps in support have historically meant services keep other formats available as well.
- Overtaken in efficiency. AV1 is generally reported to be more efficient than VP9, at the cost of heavier encoding.
How platforms use it in practice
A video service generally prepares multiple versions of each upload so viewers get something their device can play. A browser that supports VP9 may be sent a VP9 stream at a particular resolution, while a device that does not may receive H.264. The player chooses among them, and adaptive bitrate logic switches quality as network conditions change. Preparing those versions is part of the wider streaming pipeline.
Why VP9 still matters
VP9 is sometimes treated as a stepping stone to AV1, which is fair, but it also did real work. It showed that a royalty-free codec could be competitive at scale, it saved bandwidth for a very large video platform, and much of its design lived on in AV1. How long it stays in use depends on how quickly AV1 and later formats reach the devices people actually own, which is uncertain. In the meantime, VP9 remains a widely supported option on the web.