How is a severely scratched CD still readable sometimes?

Question

I’ve noticed this on DVDs and BluRays but also with games on any console. I’ve rented a movie and the disk is riddled with scratches and I’m sure it’s not going to read, but it somehow does. However, sometimes it hitches. But playing it back on a different DVD player presents no issues at all. What’s happening here?

In: 6

Answer 1

Adding to the above, I’m convinced that some of the cheaper readers are designed without enough processing grunt, or good enough firmware, to implement all of the layers of error correction. Thus a scratched disc won’t play on them but will on a higher quality device.