How do you locate intraframes in editing?

MichaelJ70

Newbie Location: England Joined: Jun 14, 2012 03:00 Messages: 35 Offline

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Jun 23, 2013 05:08

I am learning, if slowly! I have read this on another forum, concerning I frames: "So when you edit an MPEG-2 video all we have to do is back up to the nearest I frame and recode the few frame between it and the edit point to get a clean cut."

This is new to me. I think I now understand what an intraframe is, and what it does, but can someone explain how to back up to the nearest I frame etc. and recode or is this stuff that as a simple-minded tecchie I don't NEED to understand??

MichaelJ70 Michael J.

stevek

Senior Contributor Location: Houston, Texas USA Joined: Jan 25, 2011 12:18 Messages: 4663 Offline

Jun 25, 2013 10:45

Apparently not many understand your question. Perhaps if you asked about "key" frames.

Where did you get that quote from?

I have never worried about it in 10 years of family video. The programs always cut where I wanted them to without needed to back up to a key (or I frames).

Perhaps if you tell us if you are having an issue with trimming a video? .
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Anything I post unless stated with a reference is my personal opinion.

MichaelJ70

Newbie Location: England Joined: Jun 14, 2012 03:00 Messages: 35 Offline

Jun 25, 2013 12:20

Apologies. Stevek. I should have specified Key Frames although when Googled they are also referred to as 'intraframes'. I'm not having a specific issue, but I understand that Key frames are important carriers of information. When I cut a section of clip (not in PowerDirector by the way - I use a separate programme for trimming lengths of raw footage. This enables me to retain AVCHD format before editing in PowerDirector) I sometimes see a warning 'you are cutting several Key Frames; do you want to continue?'. I just want to be clear about what I am doing, and whether I am missing something important. But you seem to be saying ignore key frames?
MichaelJ70 Michael J.

stevek

Senior Contributor Location: Houston, Texas USA Joined: Jan 25, 2011 12:18 Messages: 4663 Offline

Jun 25, 2013 12:24

I'm not saying to ignore them. In the home video editing I'm doing, I don't worry about them. Are you using a pro video editing program (don't name it). What does that program say about key frames? Why are you using it rather than just using PD 10? PD 10 should accept your AVCHD video as is. .
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BoilerPlate: To posters who ask for help -- it is nice to thank the volunteers who try to answer your questions !
Anything I post unless stated with a reference is my personal opinion.

MichaelJ70

Newbie Location: England Joined: Jun 14, 2012 03:00 Messages: 35 Offline

Jun 25, 2013 12:50

I'm actually using PD11, as of this week upgraded from PD10, and like it very much, so that provides the answer to your first query. PD10 and PD11 will accept AVCHD, but they will not allow me to make basic cuts to raw clips and allow me to return them to my library as AVCHD. I am making some quite complex educational videos from large numbers of clips, and I was finding that my 'raw' video library was taking up an awful lot of hard drive space without some basic trimming out of 'dross'.

However, having Googled for more information about keyframes, and checked out their use in PD11, I am inclined to go along with your suggestion and ignore them!

MichaelJ70
Michael J.