timecode differences in AVI and MPEG-2

[coeng73]

I have a question regarding a difference in timecodes between an AVI file and its MPEG-2 encoded "equivalent".

In Premiere I rendered a 18 minute project as an AVI and wrote down the time codes that would represent the start of each chapter in a DVD.

When I encode the video into MPEG-2 (using at least four different methods...TMPGEnc, Studio 7, AVISynth, Ligos LSX-MPEG) and import it into DVDit, I noticed a difference in timecodes when inserting chapter points. During the first 8-9 minutes, when I type in the timecode of a chapter, it correctly goes to the correct start frame and creates the chapter. Every chapter after that point is off by a few frames. In other words, if I type in the timecode 11:42.15 that I had written down to mark Chapter 5, the timeline marker jump a few frames into chapter 5. I have to back off a few frames to get the chapter point correct (i.e. 11:42.12).

Why is this? I was hoping that I could set my chapter points most accurately using this method (versus setting them with the DVDit timeline which is a pain).

What can I do to get around this?

[paintmodel]

I'm not sure if you can. I have noticed that you MPEG-2 stream will have different time codes depending on what types of encoding you use and what bit rates you set your conversion at. I have especially noticed this when using 2 pass VBR conversions. My timecodes move all over the place, backwards and forwards depending on the stream rate per scene.

[BJ_M]

time is time and the timecode would be the same between avi and mpeg2 even after encoding if you didnt change something - i.e. change from 29.97 NDF to DF or to 30fps NDF

are you doing your avi in drop frame ? because tmpgenc will always encode in NDF (i think - or it was the otherway) which will cause the time code to drift .. unless you do both the same .. you can download freeware timecode calculaters to figure out the diff.

the timecode would also be off if frames were added or removed.

time written as 00:00:00;00 is drop frame and time written as 00:00:00:00 is non drop frame - ussually , though a few authoring apps don't use this rule. And more than 1 authoring app has caused me grief becuase of this.
With CCE it is selectable , w/ tmpgenc it is not.

frankly the whole timecode thing relating to NTSC is a mess and can mess you up (specially considering also audio is ussually expessed as 30fps and edited that way as most forget to set their audio editor up for ntsc timecode)