Stray frame from previous or next clip appears...

J_Mac wrote on 12/5/2004, 4:00 PM
DVD 2b, My main menu has 1 button going to a page with 2 buttons. 1 button plays all for vid 1 and the 2nd button goes to another page with 28 sub-clip buttons for vid 1.
My problem has been to set the in-out points on the subclips so that the subclip starts on a specific frame and ends on a specific frame. The subclips seem to pick up a stray frame from the end of the previous clip; when beginning to play the sub clip, or the beginning of the next clip; at the end of playing the sub clip
.
All my subclip chapter markers and in-out points are lined up exactly together and are at least 1 second between sub clips. Is their a trick to this that I'm am missing?
Each TL subclip, naturally, displays all the chapter markers for all the subclips.
Would deleting all the markers except those for the individual subclip I am working on help?

This problem does not show up in the preview, or TL players, so I have to prepare and burn to test. I've done this a dozen times, and has taken all week to adjust and test.
Thanks for any help or advice. John.

Comments

ScottW wrote on 12/5/2004, 5:28 PM
You cannot set frame specific in/out points. With DVDA basically you have +/- 1/2 second that the clip will actually begin in.

I have found that when you render your MPEG-2, if you reduce the number of I Frames from 15 to some smaller value (via the customize button) that you can gain some additional control, but I've not done an extensive amount of testing yet to see if there are any undesireable side effects - certainly your mpeg's will be larger.

--Scott
J_Mac wrote on 12/5/2004, 6:52 PM
So reading into your response, if I put my in-out points at the I frames, I should be ok? How do I determine where they are, or are they simply at every 1/2 second? Thanks, Scott for your help. John.
ScottW wrote on 12/6/2004, 5:14 AM
The in/out points must be on an I frame - clarification - when I spoke of lowering the I frame value on the video tab when rendering, what I was doing was reducing the number of frames before an I frame gets inserted.

The default value is 15, so an I frame gets inserted every 15 frames.

By taking the value down to 4 (for example) an I frame will get inserted every 4 frames, so you have better accuracy on your chapter points at the expense of having more I frames (and hence a larger file).

--Scott
J_Mac wrote on 12/6/2004, 7:20 AM
Thanks, Scott. Will the Main Concept encoder automatically adjust the B and P frames during encoding, or do I determine the appropriate values for the video block? Or are they really unrelated?
Here is the info that prompted my question. Certainly more info than I can digest in one sitting.
Thanks again for your help. John.
J_Mac wrote on 12/6/2004, 7:34 AM
Sorry left out the link. John

http://bmrc.berkeley.edu/research/mpeg/faq/mpeg2-v38/faq_v38.html
ScottW wrote on 12/6/2004, 12:47 PM
So far as I can tell, the MC encoder will adjust everything else as needed.
J_Mac wrote on 12/6/2004, 6:57 PM
Scott, I used the 12 I frame setting, and changed the B between 1 and 2. Both gave me blockiness and a degraded picture. Setting the in/out points became difficult, trying to determine how many frames to the right or left the closest I frame was at I=12 vs I=15.
I solved my overall problem by simply offsetting the out points and the next in point by 30 frames or more, and stayed with the 15 setting.
Unfortunately my client gave me no pre/post roll, so it does effect each clip. I had my preview tonight and they loved the DVD, but we'll see after they preview this week. Thanks again, John
ScottW wrote on 12/7/2004, 5:37 AM
I wouldn't have thought that changing the I frame settings would have had that type of effect (I've not played with the B frame settings). An I frame is a complete frame - that's why chapter points have to happen on them, because when the player jumps to that frame it has to have a starting point. B and P frames are not complete.

Anyway in the testing that I did, I lowered just the I frame setting down to 2. The resulting mpg did not appear to be visually any different than the default setting of 15 and I had a lot more control over things.

--Scott