What Is a Codec, Actually?
A codec (coder-decoder) is an algorithm that compresses video data. Without compression, one minute of 1080p video is 10+ GB. With H.264, it's 100–200 MB. Same visual quality, 99% smaller.
The catch: newer codecs compress better, but require more CPU to decode and may not be supported on older devices.
The Four Codecs Worth Knowing
H.264 (AVC) — The Universal Standard
Released in 2003. Still the most-used codec in the world, and for good reason.
The numbers:
- File size: baseline (everything else is compared to this)
- Decode support: 100% of devices made in the last 10 years
- Encode speed: fast
- Quality at low bitrates: good
Use when: compatibility matters more than anything else — social media, email, clients who might be on older devices, embedding on websites.
Real-world example: A 60-second 1080p clip at 8 Mbps in H.264 = ~60 MB.
H.265 (HEVC) — Better Compression, Patchier Support
Released in 2013. Compresses 40–50% better than H.264 at identical visual quality.
The numbers:
- File size: ~50% smaller than H.264
- Decode support: ~90% of modern devices (not all older Android, some Linux setups)
- Encode speed: 2–5× slower than H.264
- Quality at low bitrates: excellent
Use when: you're storing large files (4K footage, archives), targeting modern devices, or uploading to platforms that support it (YouTube, Vimeo).
Real-world example: Same 60-second 1080p clip at 8 Mbps in H.265 = ~30 MB (same quality as H.264 60 MB).
VP9 — Google's Open Alternative
Released by Google in 2012. Royalty-free, comparable compression to H.265.
The numbers:
- File size: ~30–40% smaller than H.264
- Decode support: Chrome, Firefox, Edge, Android, YouTube — not Safari/iOS natively
- Encode speed: very slow
- Quality at low bitrates: excellent
Use when: web delivery where you control the player (e.g., a Chrome-only internal tool), or YouTube uploads (YouTube re-encodes everything to VP9 anyway).
AV1 — The Future
Released in 2018 by the Alliance for Open Media (Google, Netflix, Apple, Amazon, Mozilla). Royalty-free. Best compression available.
The numbers:
- File size: ~30% smaller than H.265, ~50% smaller than H.264
- Decode support: growing rapidly — all modern browsers, iPhone 15+, most 2022+ Android devices
- Encode speed: 10–50× slower than H.264 (hardware encoders are catching up)
- Quality at low bitrates: the best
Use when: streaming (Netflix, YouTube use it), long-term storage where encode time doesn't matter, future-proofing your archive.
Side-by-Side Comparison
| Codec | File Size | Compatibility | Encode Speed | Best For |
|---|---|---|---|---|
| H.264 | Baseline | Universal | Fast | Everything, everywhere |
| H.265 | −50% | Modern devices | Slow | 4K, storage, modern platforms |
| VP9 | −40% | Web/Android | Very slow | Web video, YouTube |
| AV1 | −50%+ | 2022+ devices | Very slow | Streaming, archives |
Which Codec for Which Use Case
Uploading to YouTube → H.264 or H.265. YouTube re-encodes to VP9/AV1 on their end. Upload in H.264 for speed, H.265 for smaller upload file.
Sharing with clients → H.264 always. You don't know what device they're on.
Website background video (muted loop) → WebM (VP9) for Chrome/Firefox, MP4 (H.264) as fallback. Serve both.
4K archiving → H.265 or AV1. H.265 if you need compatibility, AV1 for maximum compression.
Mobile-first content → H.264 at 720p. Still the safest for widest device support.
Streaming service / large audience → AV1 if your encoder supports hardware acceleration. Otherwise H.265.
What About the File Format?
Codecs and file formats are different things:
- .mp4 = container that can hold H.264, H.265, or AV1
- .webm = container that holds VP9 or AV1
- .mkv = flexible container, holds anything
H.264 in MP4 is the universal safe choice. Most video hosting platforms accept it and re-encode on their end anyway.
Compress Your Video Now
Video Compressor — upload your video, choose output format (MP4 or WebM), select quality. FFmpeg handles the encoding using the same codec logic described above. No account, no watermark.