在家里刻录CD或DVD时，您可能会感到奇怪，为什么数据总是从中心向外添加？如果数据被反方向添加，就像旧的乙烯基记录被修复一样，这真的有关系吗？还有别的吗？今天的超级用户问答帖子回答了一位好奇的读者的问题。

今天的问答环节是由SuperUser提供的，SuperUser是Stack Exchange的一个分支，是一个由社区驱动的问答网站分组。

问题

超级用户读者Burgi想知道为什么CD和DVD会从中心向外添加数据：

Recently, I had to burn a DVD for the first time in ages and I was wondering why CDs and DVDs start adding data in the center of the disc and work their way toward the outer edge.

Older rotating-disc media like vinyl records started from the outer edge and went in toward the center, so it could not have been for historical reas***.

I am looking for good sources that explain the reasoning for this data structure/setup.

为什么CD和DVD从中心向外添加数据？

答案

超级用户贡献者DavidPostill为我们提供了答案：

Why do CDs and DVDs add data from the center outwards?

Note that the assumption made in the question above is incorrect.

Summary

• For historical reas***, writing (and reading) from the inside makes sense (different sized discs are possible as explained in other answers).
• For read performance reas***, modern discs may be written (and read) outside in or even in both directi*** (dual layer).

Notes

• Most discs are a standard size.
• Commercially produced CDs and DVDs are not written at all, they are stamped on a press.

Source: The Difference Between Commercial and Home-Recorded DVDs

The rest of this answer concentrates on the performance aspect. The excepti*** to writing (and reading) from the inside are Xbox games (and other game c***oles’ games) and Dual Layer DVDs (movies).

Xbox Games

Xbox games have the data written from the outside in for performance reas***. Since the outside is spinning faster than the inside, the data can be read faster.

Source: Hardware Behind the C***oles – Part I: Microsoft’s Xbox

Dual Layer DVDs (Movies)

Dual Layer DVDs can be written in either direction, there are two write modes. Most movies are written using the opposite track path technique. A movie will be split across across the layers, so no seek back to the inner edge is needed at the layer change point.

Source: DVD-R DL

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