Bandwidth & Performance¶
Excalibur SAM (Streamed Access Management) uses two distinct technologies to deliver remote access: Pixel-based Streaming (for Desktop/Terminal access) and Vitro DOM-based Streaming (for Web Application access).
Because these technologies handle data differently, their bandwidth footprints vary significantly.
Pixel-Based Streaming (RDP, VNC, SSH)¶
Used for full desktop environments or server consoles. This method captures the screen as a series of images and streams them to your browser.
Bandwidth Benchmarks (at 1080p)¶
| Activity Level | Estimated Bandwidth | Data Used per Hour |
|---|---|---|
| Idle / Static Screen | 5 – 20 kbps | ~5 – 10 MB |
| Light Office Work (Email, Coding) | 100 – 300 kbps | 45 – 135 MB |
| Active Web Browsing (Scrolling) | 500 kbps – 1.5 Mbps | 225 – 675 MB |
| High Motion / Video | 2 Mbps – 8 Mbps+ | 1 GB – 3.5 GB+ |
Why It Varies¶
- The Pixel Delta Principle — Excalibur SAM only transmits pixels that change. If your screen is static, bandwidth is negligible. If you play a video, every pixel changes 30–60 times per second, increasing data usage.
- Protocol Optimization — SSH is the lightest (text-only, <50 kbps), while RDP is more efficient than VNC due to advanced caching.
Vitro: Web App Streaming (DOM-Based)¶
Used for secure, isolated web application access. Unlike pixel streaming, Vitro does not send images of the website. Instead, it observes the structure of the page (the DOM) and sends the "blueprint" to your browser.
How Vitro Works¶
- Full Snapshot — when you first open a session, Vitro sends a serialized snapshot of the target website's state.
- Mutation Tracking — Vitro monitors the target site for "mutations" (changes in text, new buttons, or UI updates).
- Serialized Delivery — only the specific change is serialized and sent to your browser to be reconstructed.
- Isolation — all scripts (JavaScript) run on the secure Excalibur server, not your local machine. You receive the visual structure without the security risks.
Bandwidth Impact¶
- Native-like Traffic — bandwidth usage is almost identical to browsing the original website directly.
- Efficiency — because it sends text-based "instructions" rather than image frames, Vitro is significantly lighter than RDP or VNC for web-based tasks.
- Lower Overhead — scrolling a long page in Vitro uses a fraction of the bandwidth compared to Pixel Streaming, as it only requires updating the scroll position rather than re-rendering thousands of pixels.
Comparison at a Glance¶
| Feature | Pixel Streaming (RDP/VNC) | Vitro (Web App Streaming) |
|---|---|---|
| Delivery Method | Video-like stream of pixel tiles | Serialized DOM mutations/blueprints |
| Best For | Desktop OS, Legacy Apps, Servers | Web Portals, SaaS, Admin Consoles |
| Bandwidth | Highly dependent on screen motion | Nearly identical to native web traffic |
| Visual Quality | Depends on compression/bitrate | 1:1 "Pixel Perfect" (it is the actual site) |
Monitor Your Real-Time Usage¶
You can verify the performance of either stream type directly in your browser:
- Press F12 to open Developer Tools.
- Go to the Network tab and select WS (WebSockets).
- Select the active Excalibur session.
- View the Messages / Frames tab to see the size (in bytes) of the data being sent. For Vitro, you will see small "mutation" packets; for Pixel Streaming, you will see larger binary "data" packets.
Optimization Tips¶
- For Pixel Streams — disable desktop wallpapers and menu animations to reduce the number of "changed pixels" the system must send.
- For Vitro — since Vitro is already highly optimized, ensure your local browser is up to date to handle the reconstruction of the DOM mutations as efficiently as possible.