Adaptive Bitrate Streaming
Every video uploaded to AVCaption is encoded into multiple resolution variants. The player picks the right variant based on the viewer’s actual bandwidth — switching up when the connection is fast, switching down before a buffer event happens.
This is adaptive bitrate (ABR) streaming via HLS. It’s the standard used by YouTube, Netflix, Twitch, and every modern video platform. AVCaption ships it by default on every video.
What gets encoded
| Variant | Resolution | Bitrate (target) | Use case |
|---|---|---|---|
| 360p | 640×360 | 600 kbps | Slow mobile, weak Wi-Fi |
| 540p | 960×540 | 1.2 Mbps | Moderate mobile |
| 720p | 1280×720 | 2.5 Mbps | HD on standard broadband |
| 1080p | 1920×1080 | 5 Mbps | Full HD, default desktop |
| 1440p | 2560×1440 | 8 Mbps | 2K (all tiers, including Free) |
| 2160p | 3840×2160 | 16 Mbps | 4K (Premium / Enterprise only) |
Source resolution caps the encoding ladder — a 720p source produces variants up to 720p, no upscaling. Free tops out at 2K (1440p); Premium and Enterprise unlock 4K (2160p).
How the player decides
When playback starts:
- Player fetches the master
.m3u8listing all variants with their bandwidth. - Player picks a starting variant based on the initial network probe (usually 720p or 1080p on broadband).
- Each segment download is timed. If actual bandwidth is sustainably higher, player switches up at the next segment boundary.
- If a segment download stalls or the buffer drops below threshold, player switches down immediately.
Switches happen at segment boundaries (every 6 seconds in AVCaption’s pipeline) so they’re seamless — viewers see clarity changing, not a buffering icon.
Codec support
AVCaption encodes in H.264 by default for maximum compatibility. Premium and Enterprise can opt into HEVC (H.265) for lower bitrates at same quality, or AV1 for the cutting edge. See the H.264 vs HEVC vs AV1 codec comparison for the tradeoffs.
| Codec | Compatibility | Bitrate efficiency |
|---|---|---|
| H.264 | Universal (every browser, every device since 2010) | Baseline |
| HEVC (H.265) | Safari, Edge, modern Android | ~30% better than H.264 |
| AV1 | Chrome / Firefox / modern Android | ~50% better than H.264, slow encode |
For mixed audiences, H.264 is the safe default. For 4K with bandwidth-cost concerns, HEVC saves significant bandwidth.
Why this matters for SEO and engagement
- Faster first paint — picking a lower variant on cold connection start means video plays within 1 second.
- Less abandonment — buffer events are the #1 cause of video abandonment. ABR reduces them.
- Better mobile experience — phones on cellular get a watchable lower variant instead of a stuck high variant.
- Lower bandwidth costs for viewers — viewers on metered connections get just enough quality to watch.
CDN delivery
ABR works because every variant’s segments are cached at Cloudflare edge (read more on CDN vs origin). When a viewer’s player switches from 720p to 1080p, the next segment is fetched from the nearest edge — usually under 100ms.
The first segment of the default variant is pre-warmed at upload time, so cold-start playback is sub-second on most connections.
Compared to other platforms
ABR is table stakes for serious video hosting. The differences are:
- Variant count — AVCaption ships 4-6 variants depending on source. Some platforms ship only 2-3.
- Codec coverage — AVCaption supports H.264/HEVC/AV1; some platforms are H.264 only.
- 4K support — AVCaption does 4K on Premium; Cloudflare Stream and Wistia cap at 1080p.
Get started
ABR is on by default — every video gets the full ladder up to your tier’s resolution cap. Upload a 4K test source on the free tier and watch the player switch variants live in DevTools as you throttle the network.