The four codecs in one table
| Codec | Also called | Size at equal quality | Encoding speed | Support |
|---|---|---|---|---|
| H.264 | AVC | Baseline | Fast | Practically universal |
| H.265 | HEVC | Noticeably smaller | Slower | Most recent phones and computers; patchy in browsers |
| VP9 | Similar to H.265 | Slow | Chrome, Firefox, Edge, Android, recent Safari; YouTube | |
| AV1 | Smallest of the four | Slowest | Recent hardware and browsers; growing |
Efficiency figures vary a lot with content and settings, so treat the size column as a ranking rather than a promise.
H.264: the safe default
H.264 has been the standard for sharing for well over a decade. Every phone, browser, TV and social app can play it, and hardware in nearly every device decodes it efficiently. It is the right choice whenever you do not know where a video will be played.
Compress VideoCompress Video uses H.264 by default, so the result plays everywhere.H.265 (HEVC): smaller files for your own devices
H.265 reaches similar quality to H.264 at a noticeably smaller size, and iPhones record in it by default under the High Efficiency setting. The catch is support: some browsers, older Windows machines and some apps cannot play it without extra codecs. Encoding is also slower, and in a browser, where it runs on one CPU thread, much slower.
Use it for archives and for sharing with people you know have recent devices.
VP9 and AV1: the open codecs
VP9 and AV1 are royalty-free codecs designed for the web. YouTube streams most video as VP9 or AV1. VP9 sits in a WebM file and compresses about as well as H.265. AV1 is more efficient still, but encoding it is very slow without dedicated hardware, and older devices cannot decode it smoothly.
Aback Video's in-browser engine cannot decode AV1 input yet. If a file is AV1, the tools will tell you so instead of failing silently. Video Info shows the codec of any file.
Which codec should you choose?
- Sending to anyone, uploading to social apps: H.264.
- Keeping your own library small on recent devices: H.265.
- Web pages where you control the player: VP9 (with an H.264 fallback).
- Long-term efficiency when you have hardware or time to encode: AV1.
Remember that social apps re-encode whatever you upload. Sending them a heavily compressed H.265 file gains little: a clean H.264 file at a good bitrate gives their encoder more to work with.
What about the audio?
Every video codec is paired with an audio codec, and the pairing follows the container. The audio is a small part of the file size, so the choice is mostly about compatibility.
| Audio codec | Usually paired with | Notes |
|---|---|---|
| AAC | H.264 and H.265 in MP4 or MOV | The standard for sharing; 128 kbps is plenty for most video |
| Opus | VP9 and AV1 in WebM | Very efficient, excellent for speech at low bitrates |
| Vorbis | VP8 in WebM | Older open codec, largely replaced by Opus |
| MP3 | Older AVI files | Universal for audio files, less common inside modern video |
When you convert a video between containers, the audio may need converting too even if the picture is copied. A WebM with Opus audio moved into an MP4 for maximum compatibility, for example, usually gets AAC audio.
Convert VideoConverts the audio automatically when the new container needs a different codec, and copies it when it does not.Questions
Is H.265 better than H.264?
It is more efficient, giving a smaller file at similar quality, but it is slower to encode and not supported everywhere. H.264 remains the safest choice for sharing.
Why does my iPhone video not play on Windows?
iPhones often record in HEVC (H.265). Some Windows setups need an extra codec to play it. Converting to H.264 MP4 fixes it.
Does YouTube use VP9 or AV1?
YouTube re-encodes uploads and streams them in several codecs, including VP9 and AV1, choosing based on your device. You can upload H.264 and let it handle the rest.
Can Aback Video encode AV1?
Not at the moment. The browser engine encodes H.264, H.265 and VP8/VP9 WebM, and it cannot decode AV1 input yet.