Beginner Question: Documentation for mpeg2 (ff) settings?

[bbruecker]

Hi,

I'm removing advertisments from dvb-t recordings. I would like to keep the quality of the source. So I tried to save the file in copy mode, I got a warning:

"The video is in copy mode but the cut points are not on keyframes.
The video will be saved but there will corruption at cut point(s).
Do you want to continue anyway ?"

From the wiki article http://www.avidemux.org/admWiki/doku.php?id=using:b-frames and http://www.avidemux.org/admWiki/doku.php?id=using:i-framesI have learned I should keep the order. So I think there are two options for me:

• I cut on key frames: this means I loose some pictures. Result is, the film "jumps" sometimes. I have to say, I don't like that.
• I try Mpeg2 (ff) output.

I'm not an expert for the settings, and for a non-expert they are not self-explaining. Is there a documentation for the Mpeg2 (ff) settings? Or in other words: What settings would you recommend to me, to keep the source source quality?

Thx!

[AQUAR]

Maybe read this part of the WIKI.
http://www.avidemux.org/admWiki/doku.php?id=using:main_window_-_qt_version

Make the cut's on Intra-Frames (AKA Key Frames) by using the navigation buttons for key frames (ones with >>).
Cutting out adverts, in Copy Mode, by starting and finishing on I frames, should be fine.
Don't know what you mean by jumps, but deleting adverts this way should not add artifacts.

If you recode with Mpeg2 you will loose some quality.

[bbruecker]

AQUAR, thank you for the replay,

Well, I try to explain it in different way. If I only cut on Intra Frames/Key Frames I will loose in most cases some B-Frames (other pictures). This means, I will loose some pictures. It might not seem to be much, but in my cases its a bit disturbing. The tv company very often repeats after advertisement blocks parts of the film which was before the advertisement block. I like the feature of avidemux to set cut points in a way to make the pictures really fit to each other, in other word, gap-less. This kind of gap-less cutting is not possible, because sometimes the pictures which are fiting, are b-Frames. I will loose those pictures, if I only cut on Intra Frames. The result are in that case gaps (ore repeating of some pictures).

Well if I ignore the warning about cut points, which are not key frames in copy mode, VLC seems to be able to keep audio and video in sync (or the difference is not recognizable) and I don't see other effects. Kodi and Quicktime seems to be able to deal with that copy mode files as well. But I would like to keep standards -- who knows if those media players will keep standards in future time in a more  restrictive way. Thats why I'm asking.

Are there other possibilities then either to cut only by Intra Frames or re-encode MPEG2 with loosing quality? I don't care for file size or rendering time (if the size of the file will not be double of the source or it will takes days for cutting one film).

[AQUAR]

Okay, I think I understand your editing problem.
You need smart copy to re-encode just those bits with the resulting orphan frames around your cut points.
ADM 2.6 is time based and AFAIK cannot do smart copy because of its reliance on the codec doing frame ordering.
If you're media has mpeg2 in it, then ADM 2.5 (different program!) which is frame based (has control over frame ordering), has a smart copy function. So strange as this seems, go back to the deprecated ADM 2.5.6 (it deals better with older codecs!).

Note that this advice is from an end user perspective (not expert on the workings of ADM).

You can run both along side each other.