A codec (coder-decoder) is software or hardware that compresses raw video data for efficient storage and transmission, then decompresses it for playback. Without codecs, a single minute of uncompressed 1080p video would require over 10 GB of storage. Modern codecs reduce this to just 50-150 MB while maintaining visual quality.
How video codecs work
Video codecs exploit two types of redundancy to compress data: spatial redundancy (similar pixels within a single frame) and temporal redundancy (similar content between consecutive frames). The encoder analyzes each frame, predicts content based on previous frames, and stores only the differences.
Intra-frame compression: removes redundancy within a single frame (similar to JPEG)
Inter-frame compression: stores only differences between consecutive frames
Motion estimation: predicts how objects move between frames to reduce data
Quantization: reduces precision of less visually important data
Entropy coding: applies lossless compression to the final bitstream
Common video codecs
The video industry has evolved through several generations of codecs, each offering better compression efficiency at the cost of increased encoding complexity.
Codec
Year
Efficiency vs H.264
Browser support
License
H.264 / AVC
2003
Baseline
Universal
Licensed (MPEG LA)
H.265 / HEVC
2013
~50% better
Safari, Edge
Licensed (complex)
VP9
2013
~30-40% better
Chrome, Firefox, Edge
Royalty-free (Google)
AV1
2018
~50% better
Chrome, Firefox, Edge, Safari 17+
Royalty-free (AOMedia)
Codec vs container format
A common source of confusion is the difference between a codec and a container format. The codec defines how video is compressed (H.264, VP9, AV1). The container format defines how compressed video, audio, subtitles, and metadata are packaged together (MP4, WebM, MKV). One container can hold different codecs: for example, an MP4 file can contain H.264 or H.265 video.
How Videas handles codecs
Videas supports multi-codec streaming, automatically transcoding your uploads into H.264, H.265, and VP9 renditions. The Videas player detects each viewer's browser and device capabilities, then selects the most efficient codec available. This means Chrome viewers may receive VP9 (smaller files, same quality) while Safari viewers receive H.264 or H.265 — all from a single upload, with no extra configuration needed.
A video codec is software that compresses (encodes) video for storage and transmission, then decompresses (decodes) it for playback. Common codecs include H.264, H.265, VP9, and AV1.
H.264 is the safest choice for universal compatibility. However, newer codecs like VP9 and AV1 offer significantly better compression, meaning smaller files at the same quality. Videas automatically transcodes into multiple codecs and serves the best one to each viewer.
H.265 (HEVC) achieves roughly 50% better compression than H.264 at the same visual quality. However, H.265 has limited browser support and complex licensing. VP9 and AV1 offer similar compression gains with broader, royalty-free availability.