eDP Bandwidth API — Documentation (CVT v1 r1.2, Reduced Blanking)

Base URL

https://www.promptbox.cn/api/edp.php

Protocol

HTTPS

Auth

None (public)

Formats

Request: GET POST (JSON) • Response: application/json

Rate limits

No formal limit; please cache and be considerate.

Version

1.0.0 (Calculator parity with UI tool provided by user)

Overview

This endpoint calculates the active pixel clock and required DisplayPort/eDP transport bandwidth for a given timing using CVT v1 r1.2 Reduced Blanking assumptions. It also suggests a minimal lane/rate configuration that meets the transport requirement. Optional DSC 3:1 transport compression can be applied.

Model: CVT v1 r1.2 (RB). Horizontal blanking fixed to 80 px. Vertical blank minimum 460 µs. Pixel clock is rounded down to the nearest 1 kHz step. DisplayPort 8b/10b encoding overhead included.

Endpoint

GET  /api/edp.php?resolution=2560x1600&refresh=120&bpp=30&dsc=1
POST /api/edp.php
Content-Type: application/json

{
  "resolution": "2560x1600",
  "refresh": 120,
  "bpp": 30,
  "dsc": true
}

Request Parameters

Name	Type	Required	Description	Examples
`resolution`	string	yes	Active resolution in `H×V`. H is rounded down to a multiple of 8 cells.	`2560x1600`, `2880x1800`, `3840x2400`
`refresh`	number	yes	Vertical refresh rate in Hz. Must be > 0. Supports fractional values.	`60`, `120`, `59.94`
`bpp`	number	yes	Transport bits per pixel (e.g., 24 for 8bpc RGB, 30 for 10bpc RGB).	`24`, `30`
`dsc`	boolean \| number	no	Apply 3:1 DSC transport scaling if true/1.	`true`, `false`, `1`, `0`

Response Schema

Field	Type	Description
`pixel_clock_mhz`	number	Active pixel clock after RB rounding (MHz, 3 decimals).
`required_bandwidth_gbps`	number	Raw DP transport including 8b/10b overhead (Gbps) without DSC.
`effective_bandwidth_gbps`	number	Transport after optional DSC 3:1 scaling; equals `required_bandwidth_gbps` if DSC disabled.
`dsc_applied`	boolean	Whether DSC reduction was applied.
`recommended_link`	string	Suggested minimal lanes/rate among {1/2/4 lanes} × {1.62, 2.7, 5.4, 8.1 Gbps}.

HTTP Status Codes

200 OK — Successful calculation.
400 Bad Request — Validation error (missing/invalid parameters).
5xx Server Error — Unexpected error.

Error Format

{
  "error": "Parameter 'resolution' is required (e.g. 2560x1600)."
}

Validation & Calculation Notes

Horizontal active is rounded down to the nearest multiple of 8 pixels.
RB horizontal blanking fixed at 80 px (RBv2-style simplification).
Minimum vertical blank time: 460 µs.
Pixel clock rounding: floor to 1 kHz steps.
Encoding overhead: 8b/10b (×10/8).
DSC option scales transport by ~1/3 (i.e., 3:1 compression) for link sizing.
Recommended link chooses minimal lanes first, then the lowest per-lane rate that meets required Gbps.

Security

No authentication is required. Use HTTPS. Consider client-side caching and input validation.

Fair Use

No formal rate limit; please avoid high-frequency polling. Batch inputs on your side when possible.

Versioning

1.0.0 — Initial public release; parity with the provided HTML tool logic.

License & Warranty

Provided “as is,” without warranty of any kind. Engineering due diligence is recommended before production decisions.

Quick Examples

GET (query string)

curl "https://www.promptbox.cn/api/edp.php?resolution=2560x1600&refresh=120&bpp=30&dsc=1"

POST (JSON)

curl -X POST "https://www.promptbox.cn/api/edp.php" \
  -H "Content-Type: application/json" \
  -d '{ "resolution": "2560x1600", "refresh": 120, "bpp": 30, "dsc": true }'

JavaScript (fetch)

const res = await fetch("https://www.promptbox.cn/api/edp.php", {
  method: "POST",
  headers: { "Content-Type": "application/json" },
  body: JSON.stringify({ resolution: "3840x2400", refresh: 120, bpp: 30, dsc: true })
});
const data = await res.json();

Python (requests)

import requests
payload = {"resolution":"2880x1800","refresh":120,"bpp":30,"dsc":True}
r = requests.post("https://www.promptbox.cn/api/edp.php", json=payload)
print(r.json())

PowerShell

$body = @{ resolution = "2560x1600"; refresh = 120; bpp = 30; dsc = $true } | ConvertTo-Json
Invoke-RestMethod -Method Post -Uri "https://www.promptbox.cn/api/edp.php" -ContentType "application/json" -Body $body

PHP

$payload = ["resolution" => "3200x2000", "refresh" => 60, "bpp" => 24, "dsc" => false];
$ch = curl_init("https://www.promptbox.cn/api/edp.php");
curl_setopt_array($ch, [
  CURLOPT_POST => true,
  CURLOPT_HTTPHEADER => ["Content-Type: application/json"],
  CURLOPT_POSTFIELDS => json_encode($payload),
  CURLOPT_RETURNTRANSFER => true
]);
$resp = curl_exec($ch);
curl_close($ch);
$data = json_decode($resp, true);

Sample Responses

Success (DSC on)

{
  "pixel_clock_mhz": 563.200,
  "required_bandwidth_gbps": 21.120,
  "effective_bandwidth_gbps": 7.040,
  "dsc_applied": true,
  "recommended_link": "2 lanes @ 5.40 Gbps (capacity 10.80 Gbps)"
}

Success (DSC off)

{
  "pixel_clock_mhz": 563.200,
  "required_bandwidth_gbps": 21.120,
  "effective_bandwidth_gbps": 21.120,
  "dsc_applied": false,
  "recommended_link": "4 lanes @ 5.40 Gbps (capacity 21.60 Gbps)"
}

Error (400)

{
  "error": "Invalid resolution format. Use e.g. 2560x1600."
}

Try it

(results will appear here)

Changelog

2025-09-28 — Initial HTML documentation published.

Contact

Questions or issues? Open a ticket in your repo or contact the maintainer of /api/edp.php.