Couple of definition questions

[cyberbob25]

I've made several backups now using Rebuilder and I'm starting to understand most aspects of this art that you guys have mastered so well. However, I just wanted to know the definition of a few things that I couldn't find by searching.

First, what is the GOP?

Second, what is the difference between a transcoder, and an encoder? Isn't transcoding still encoding?

Sorry if these are answered elsewhere, but I've been unable to find these.

[jggimi]

A "GOP" is a Group of Pictures. It's a key part of all MPEG compression technology. A group always starts with an Intra frame, or I-frame. This frame is also called a Keyframe. Additional frames in the group, if any, may be Predicted frames (P-frames)or Bidirectional frames (B-frames). These latter types will not have complete image information.

"Transcoding" means to convert content from one format to another, while "encoding" means to place the content into a format. One uses "encoding" when converting from uncompressed video or audio, and "transcoding" when going from one compression format to another. This gets confusing, as many of the processes we use include a technology called frameserving, which, during transcoding, presents uncompressed content to an encoder. Most of us don't sweat about the difference, and use the terms interchangeably.

[Mac Sidewinder]

Most people also agree that an encoder (like Cinema Craft) does a better job (visually) than a transcoder (like those built in most "one click" dvd copy programs).

Mac

[cyberbob25]

Thanks guys!