Video Codec Guide: H.264, H.265, VP9, and AV1 Explained

A video codec compresses and decompresses video data. The codec determines file size, quality, compatibility, and how long encoding takes. Choosing the right one matters — the wrong choice means larger files, slower uploads, or playback failures on older devices.

Here is a plain-language breakdown of the four codecs you will encounter most often.

H.264 (AVC) — The Universal Standard

Full name: Advanced Video Coding Container: MP4, MKV, MOV Released: 2003

H.264 is the most widely supported video codec in history. Every device made in the last 15 years plays it: iPhones, Android phones, smart TVs, game consoles, browsers, and every media player.

When to use H.264:

Typical file size: A 1-hour 1080p video at high quality is roughly 4–8 GB.

Quality setting: CRF 18–23 for high quality. Lower CRF = larger file, better quality.

H.264 is the safe default. If you are unsure which codec to use, use H.264 in an MP4 container.

H.265 (HEVC) — Better Compression, Fewer Devices

Full name: High Efficiency Video Coding Container: MP4, MKV, MOV Released: 2013

H.265 delivers the same visual quality as H.264 at roughly half the file size. A 4 GB H.264 file becomes approximately 2 GB in H.265 with identical quality.

The tradeoff is compatibility. Older Android phones, some smart TVs, and many web browsers cannot play H.265 without hardware support. Safari and Apple devices play H.265 well. Chrome and Firefox require hardware decoding.

When to use H.265:

Avoid H.265 when:

VP9 — Google's Royalty-Free Alternative

Full name: VP9 Container: WebM, MKV Released: 2013

VP9 is Google's answer to H.265: similar compression efficiency, but royalty-free. No patent licensing fees. This makes it the codec of choice for web video — YouTube uses VP9 extensively for HD streams.

VP9 is used almost exclusively in WebM containers for web embedding.

When to use VP9 (WebM):

Compatibility: Chrome, Firefox, Edge, and Opera play VP9 natively. Safari does not (Apple prefers H.265). iOS devices require a fallback format.

AV1 — The Future Codec

Full name: AOMedia Video 1 Container: WebM, MKV, MP4 (ISOBMFF) Released: 2018

AV1 is the next generation: up to 50% better compression than H.264 at equivalent quality. Netflix and YouTube use AV1 for bandwidth reduction at scale.

The catch is encoding speed. AV1 encoding is extremely slow — 10–50x slower than H.264. A video that takes 2 minutes to encode in H.264 might take 40 minutes in AV1. Hardware encoders (Intel Arc, newer AMD and Nvidia GPUs) reduce this significantly, but software AV1 encoding remains impractical for most users.

When to use AV1:

When to avoid AV1:

Quick Comparison

| Codec | Quality | File Size | Compatibility | Encode Speed | |-------|---------|-----------|---------------|--------------| | H.264 | Good | Larger | Universal | Fast | | H.265 | Better | 50% smaller | Good (modern) | Medium | | VP9 | Better | 50% smaller | Web browsers | Medium | | AV1 | Best | 50–70% smaller | Newer devices | Slow |

Which Codec Does VideoConvert Use?

VideoConvert encodes using FFmpeg and defaults to H.264 (libx264) for MP4 output — the universally compatible choice. WebM output uses VP9 (libvpx-vp9).

For Pro users, you can control quality via CRF settings. The codec selection is handled automatically based on your target format:

This ensures your converted files play everywhere without manual codec configuration.