which FRM to choose when cutting a video in Avidemux ?

[Editall]

Hi

I'm new to cutting but read few threads and decided to use avidemux. I don't want to compress anything so I left Video/Audio Output as Copy and Output Format as Avi muxer. BTW the video is an AVI, MPEG-4 Visual, xvid and H 263

Now, I seem to have problems with keyframes. Which one of these should I choose to cut I-frm, P-frm or maybe B-frm ?

I'm asking cause when I cut 4 parts (i-frames and p-frames) and clicked Save I got this warning



To choose my cut points I used that slider and clicked A for a beginning and B for the ending - click me

I don't know, however, if cut point should begin with I-FRM and end with I-frm or if it can end with P or B-FRM
??

I'd really appreciate your help.

[poisondeathray]

Yes, both start/end cut points should be on I-frames

You can use the "<<" and ">>" buttons in the GUI to navigate (jump to) the next keyframe




But for xvid/mpeg-4, avidemux has "smart rendering" capability - it basically re-encodes the few frames around a cutsite. Thus you can have frame accuracy and do not have to cut on keyframes. If you want to try this, set video to "xvid mpeg4". A pop up box will come up when yiou save it and it will ask if you want to "smart render" and asks the quantizer. Lower value is higher quality. You will know it's working , because video is saved very quickly (only a few frames are re-encoded)

[Editall]

set video to "xvid mpeg4".

Where can i find this, drop down menu in Video Output ? I have avidemux 2.6.8 - click me

A pop up box will come up when yiou save it and it will ask if you want to "smart render" and asks the quantizer. Lower value is higher quality.

How can I get there ? I mean avidemux doesn't ask me about smart render/quantisizer and such.

[poisondeathray]

maybe they've removed it in that version, try another one if you can't find it. This feature has been available for many years

It will say under video output:
"mpeg4 asp (xvid4)"

The pop up should come up automatically as soon as you save it. If it doesn't something is wrong (maybe your video uses incompatible settings), or you actually did cut on keyframes.

[Editall]

It will say under video output:
"mpeg4 asp (xvid4)"

The moment I choose "mpeg4 asp (xvid4)" and click Save, it starts to encode right away, doesn't allow me to put anything, doesn't ask me about anything - click me

or you actually did cut on keyframes.

by keyframes you refer to I-FRM only, right ? The thing is I have some P and B frames I need to cut, is it possible ?

[poisondeathray]

What does mediainfoxp say about your video ? (view=>text)

You might have to set the xvid configuration to match or at least more similar characteristics

Yes I-frame is a "keyframe" in avidemux for xvid. If you cut on a P or B frame, it should be possible (hence the smart rendering, not quality loss, except for a few frames, the rest of the video is "passed" through).

[Editall]

MediainfoXP didn't work for me, couldn't run it somehow so here's MediaInfo - clickme


My xvid settings - clickme

[Editall]

poisondeathray, thanks for the info, btw what version of avidemux you are using ?

[poisondeathray]

poisondeathray, thanks for the info, btw what version of avidemux you are using ?

I don't really use avidemux or xvid for a few years, but I have a few versions on a test computer, just used for testing purposes

It used to be, that if settings didn't match, it would force a complete re-encode instead of stream copy + smart render. e.g. if the profile was different, or you set b-frames different (2 instead of 0), or some other characteristic. This is true with vdub xvid smart render as well. This is the reason for using mediainfo, gspot etc.. so you can match the xvid configuration to the source file

[Editall]

Regarding the numbers inside open parentheses, if starting p-frm has got (02) ednig should be (02) right ? To make sure A and B should have the same numbers inside parentheses right?

Will try to download some other versions of avidemux.

[poisondeathray]

I don't know that those numbers are supposed to indicate inside parentheses

You should try to match the settings. That's increases your chances of "convincing" it to smart render (avidemux calls it "smart copy"), in bot avidemux and vdub.

If another version doesn't work, you can try vdub

[MP4_loseless_cutting]

To choose my cut points I used that slider and clicked A for a beginning and B for the ending - click me

I don't know, however, if cut point should begin with I-FRM and end with I-frm or if it can end with P or B-FRM??

Your question and the answers where very helpful - thanks!

I used Avidemux 2.6.12 for loseless cutting of an MP4 video file. I was suprised that the frame selected as cutting point B was not deleted. To delete the last frame of a sequence you have to select the following frame (in my case a I-FRM) as B! After that the selected I-FRM remained and finally the last frame of the sequence I wanted to delete was gone. Now it was B-FRM, I-FRM... The video played without any hickup.

http://www.avidemux.org/admWiki/doku.php?id=using:cutting

The Edit→Delete menu entry will remove frames from [A,B) from the stream.

= The frame marked as B is not deleted! See https://en.wikipedia.org/wiki/Interval_(mathematics)#Including_or_excluding_endpoints

Make sure the B marker is an I-frame.

= The I-FRM is not deleted but the broken 'half-frames' before it, which could cause video playback hickups.