What exactly is Frame Indexing? (DVDLAB)

[zoranb]

Ive read the tutorials for DVDlab but still:
1. I dont understand when i should use Frame Indexing or what it exactly does! Can anyone explain it to me as he understands it?

2. Can i set manualy the placing of chapters? I mean can i give the time settings somewere and then execpect them just to drop
on the timecode ive given?

[FOO]

Frame indexing usually means making a list of the addresses of
the start of each frame within a file so as to reduce the time to
find a particular frame. I dunno why that fundamentally
improves chapter placement however.

[SaSi]

Chapters on DVD are not really assigned to a timecode. They are assigned to frames. And chapter points must be placed on Index frames since these are the only ones that can be properly displayed when directly seeking into them.

Another complication is that normal MPEG-2 encoding allows a frame to require information from previous frames - which is normal - and even frames before the most recent Index frame. This means that you may have an Index frame which can be properly displayed by itself and this may be followed by a B frame that depends on information 3 frames before. This causes either bad display or frozen frames depending on how clever the DVD player is.

When you load a video in DVDLab, then it can only estimate the timecodes based on timestamps in the video stream. This gives you a rough precision in placing chapters.

If you frame index the movie, then DVDLab scans it and supposedly creates a list of valid frames you can select as chapter points.

The visible difference is that once you frame index the movie. then seeking and placing chapter markers is much faster and when you place a marker it remains where you placed it. I've noticed markers move forward or backward a couple of frames when compiling if I don't frame index the movie first.

Hope the explanation was clear enough.

[FOO]

What's an Index frame ?
I frames are Intra coded frames

[andkiich]

http://www.mediachance.com/dvdlab/tutorial/indexing.html

[FOO]

So Oscar doesn't trust Gop timecodes . Good idea.
I notice there is no mention of Index Frames

[SaSi]

What's an Index frame ?
I frames are Intra coded frames

You are correct. I was doing some work with Database indices this morning and my mind was full of them..

[FOO]

I am happy to see someone is doing work. My mind is
full of something other than indices.
It's the same stuff that makes plants grow.

[zoranb]

Ok, now how can i be precise on the chapter placing in a clip? Unfortunatelly I-frames are not exact and i want to place chapter exactly on some places in a movie, is there a way to do this? Someone suggested to make a chapter.txt file and then import it. But how can i make this and what can i use to see the correct timecode or frame of the the chapter id like the scebe to start from?