What is the VP9 Codec?
VP9 is an open video compression format developed by Google as a successor to VP8 and offered under the WebM project’s royalty-free patent license. It is widely supported for web video and can compress more efficiently than H.264 for many sources.
How the VP9 Codec works
VP9 encodes pictures with block-based prediction, transforms, and entropy coding, using similarities within a frame and across frames to reduce data. It is a codec rather than a container, so deployment also requires a compatible packaging format, browser or device decoder, audio codec, and manifest declaration. Media pipelines commonly keep VP9 as one branch of a multi-codec ladder because encoding speed and client decode support differ from those of other delivery codecs.
Key facts
- VP9 is commonly packaged in WebM for browser delivery, but container support and codec support are separate; a client may accept the container yet reject a profile or bit depth.
- Hardware decoding depends on the device and the exact VP9 profile. Falling back to software decode can increase CPU use, power consumption, and dropped frames at demanding sizes.
- Two-pass VP9 encoding can use statistics from an analysis pass to allocate bits across difficult and easy scenes, improving rate control at the cost of turnaround time.
When the VP9 Codec matters
VP9 renditions can reduce bandwidth in compatible browsers and devices, particularly at higher resolutions. The benefit must be weighed against encoding cost and clients that require another codec.