WOPC (walking OPC)

vbimport

#1

Any body in the forum knows what WOPC (walking OPC) is? Most of the drive used the techniques during writing for all types of disc (+/-r and +/- rw)…what is the benefit of WOPC technique? :confused:

thanks for your attention! :iagree:


#2

It’s a writing technique that periodically stops the burning process to adjust laser power. The purpose is to improve writing quality.

“Walking OPC” is a BenQ/Philips marketing term for intermittent OPC (optimal power control). A more proper term for intermittent or continuous OPC is Running OPC. You can do a Google search for it and get reasonable matches, including some technical papers:

http://www.google.com/search?q=running+opc

A search for “Walking OPC” will come up with mostly BenQ marketing literature.

Here’s one explanation of initial and running OPC:
http://www.mscience.com/faq64.html


#3

thanks for your prompt reply…


#4

W-OPC (Walking OPC) is not a writing technique by itself. It is an algorithm that is coupled to a write strategy (e.g. Z-CLV, P-CAV, etc.) that monitors burn quality in real-time and adjusts laser power and data transfer speed according to information passed on the drive’s main processor. Different chipsets have different implementations of W-OPC.

Regards,
TerminalVeloCD


#5

Huh? Sure it is. Technique is “a practical method or art applied to a particular task.” In this case, it is a method of adjusting laser power applied to the task of writing a CD or a DVD.


#6

According to this link http://club.cdfreaks.com/showthread.php?s=&postid=433891

“It is a technique to monitor and maintain write quality throughout the recording session. The laser power is adjusted on-the-fly throughout the writing process to maintain this optimum condition.”

But Philips preferred to used the term walking OPC “WOPC” applied on +/-R whereas running OPC “ROPC” on +/-rw disc. The algorithim, principle and objective are most likely the same. My question is: What is the main difference between those techniques? Or is it just a matter of naming and implementation of fw algorithm and depends on the developer how those things implemented?

Bottom line the purpose of techniques is used for monitoring and maintaining the quality of the disc writing and ensuring the accuracy of all marks and lands lengths across the disc. :smiley:


#7

NEC refers to their implementation as “Active OPC”.


#8

ok! so it means that every drive developer prefered to impelement with different name and approach but the main objective is to monitor and maintain the write quality.


#9

Does it really make a difference in write quality?
If so, is it minor or significant?


#10

Sometimes, pretty rarely in fact, it does make a difference, mostly with marginal media. Here’s an example, an 8x RICOHJPN R02 burn. Observe the last three power adjustments where you see notches in the white writing speed line. You can see how the PI error level (blue lines) drops every time. This disc was in danger of PI errors growing out of control as the burn approached the outer edge.


#11

It depends on the disc quality…if the disc is marginal or even bad and wopc procedure is active it will frequently compensate all possible write quality degradation including disc physical defect. Of course, the assurance and confidence level of writing quality is high if frequent wopc will perform. It would be helpful and significant specially to all marginal disc .