DVD allows for the addition of 'chapter' markers or points throughout the video, enabling quicker access than using the 'fast forward' function.
This is often compared to tracks on a CD, but a more accurate comparison would be the chapters of a book, as they are intended to be markers within one piece of content, rather than separate videos.
Chapter points can only be set on MPEG-2 I-Frames, as these are the only 'full' frames within the video stream. |
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If the location of chapter points is known before the video is encoded, 24-7 DVD can 'force' I-Frames at the required locations, ensuring frame accurate placement.
If chapter points are requested after encoding, then the accuracy can be limited by 12 - 15 frames, as this is the usual distance between I-Frames. |
