X.org/XFree86 Video Timings HOWTO

Eric Steven Raymond

Revision History
Revision 6.62013-09-22Revised by: esr
Ten years after: minor updates for X.org. kvideogen and xf86setup are dead, read-edid has a new home page.
Revision 6.52003-09-28Revised by: esr
License changed to Creative Commons.
Revision 6.42004-10-14Revised by: esr
URL fixes.
Revision 6.32003-02-22Revised by: esr
URL fixes.
Revision 6.22002-02-03Revised by: esr
Minor corrections about mode line autogeneration.
Revision 6.12001-10-29Revised by: esr
Note that VESA modes top out at 1920x1440.
Revision 6.02001-08-09Revised by: esr
Clearer explanation of DDC and EDID. This HOWTO is now basically obsolete.
Revision 5.02000-08-22Revised by: esr
First DocBook version.

This HOWTO is effectively obsolete, and has been so since 2003. Current versions of X compute optimal modelines from EDID information returned by your monitor. In addition, many of the constraints and caveats in this document applied to CRTs but no longer apply to digital flatscreens.

How to compose a mode line for your card/monitor combination under X.org (originally written for its ancestor XFree86). X distributions now include good facilities for configuring most standard combinations; this document is mainly useful if you are tuning a custom mode line for an ultra-high-performance monitor or very unusual hardware. It may also help you in using xvidtune to tweak a standard mode that is not quite right for your monitor.

Table of Contents
1. Disclaimer
2. Why This HOWTO Is Obsolete
3. Introduction
4. Tools for Automatic Computation
5. How Video Displays Work
6. Basic Things to Know about your Display and Adapter
6.1. The monitor sync frequencies
6.2. The monitor's video bandwidth
6.3. The card's dot clock
6.4. What these basic statistics control
7. Interpreting the Basic Specifications
7.1. About Bandwidth
7.2. Sync Frequencies and the Refresh Rate:
8. Tradeoffs in Configuring your System
9. Memory Requirements
10. Computing Frame Sizes
11. Black Magic and Sync Pulses
11.1. Horizontal Sync:
11.2. Vertical Sync:
12. Putting it All Together
13. Overdriving Your Monitor
14. Using Interlaced Modes
15. Questions and Answers
16. Fixing Problems with the Image.
16.1. The image is displaced to the left or right
16.2. The image is displaced up or down
16.3. The image is too large both horizontally and vertically
16.4. The image is too wide (too narrow) horizontally
16.5. The image is too deep (too shallow) vertically
17. Plotting Monitor Capabilities
18. Credits