Streaming Quality
tapflow streams each device screen as H.264 and decodes it in the browser. The resolution and decoder aren't fixed — tapflow picks one of three profiles per viewer, based on how that viewer connects, balancing image sharpness against decode cost for the path.
You don't select a profile. It follows from your relay deployment and the viewer's network, so the same device can serve a localhost-grade stream to one teammate and a bandwidth-trimmed stream to another on the road.
Profiles
| Profile | Connection | Resolution | Decoder | Experience |
|---|---|---|---|---|
| Standard (recommended) | LAN over HTTP | 1280 px | WASM (tinyh264) | Near-localhost responsiveness |
| Sharp | LAN over HTTPS (or localhost) | Native | WebCodecs (hardware) | Localhost-grade |
| Remote | External over HTTPS | 1000 px | WebCodecs (hardware) | Usable QA threshold |
Standard is what most teams use day to day — a plain-HTTP relay on the LAN. The browser decodes H.264 with the software WASM decoder, so tapflow caps the resolution at 1280 px to keep decode load low while keeping responsiveness close to localhost.
Sharp is the best tapflow can offer. On a secure context — HTTPS on the LAN, or localhost — the browser unlocks WebCodecs and decodes in hardware, so the agent sends native resolution at minimal CPU cost.
Remote covers viewers connecting from outside the LAN (a public IP). HTTPS keeps hardware decoding, but the resolution is trimmed to 1000 px because the link is bandwidth-constrained — enough for QA, at the edge of comfortable.
How your deployment maps to a profile
The profile is decided by how the browser reaches the relay — which is exactly what you choose when you self-host the relay.
| Your setup | Profile |
|---|---|
| Relay on the LAN over plain HTTP | Standard |
| Relay on the LAN over HTTPS | Sharp |
| Relay reached from outside the LAN over HTTPS (VPS, tunnel) | Remote |
To move a shared LAN from Standard to Sharp, serve the relay over HTTPS — see External access in Self-Hosting the Relay.
Why HTTPS unlocks hardware decoding
WebCodecs is only available in a secure context. Plain HTTP on the LAN is not secure, so the browser falls back to the WASM decoder — which is why Standard caps resolution and Sharp (HTTPS) doesn't.
Tuning the resolution
The profile is automatic, but you can override the resolution caps. Set these on the Mac running the agent.
| Variable | Default | Description |
|---|---|---|
TAPFLOW_MAX_SIZE | (per profile) | Cap for all platforms (px, longest side). 0 forces native resolution on every connection. |
TAPFLOW_MAX_SIZE_LAN | 1280 | Standard (LAN HTTP) cap. |
TAPFLOW_MAX_SIZE_EXTERNAL | 1000 | Remote (external) cap. |
TAPFLOW_IOS_MAX_SIZE | (per profile) | iOS-specific override. Takes precedence over TAPFLOW_MAX_SIZE. |
TAPFLOW_ANDROID_MAX_SIZE | (per profile) | Android-specific override. Takes precedence over TAPFLOW_MAX_SIZE. |
Stream quality also depends on a stable, low-latency link between the agent and the relay. For agent placement and network requirements, see Agent Setup.