Author Topic: Editing: Blank video but keep audio but in a section  (Read 7961 times)

douche

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Editing: Blank video but keep audio but in a section
« on: August 10, 2015, 12:33:18 PM »
Hi,

I need to edit videos so that, for certain sections, the screen turns black, while keeping the sound intact. So, the duration of the video would stay the same, only the visual track would be cut off.

A more elaborate way to do this would be to blur only a certain area of the screen while keeping audio, but I'd be satisfied with a simple blank screen for now.

I already know how to cut scenes from movies using Avidemux 2.6, setting markers, using delete. Can anybody please tell me if it's possible (and how) to "cut" (make blank) only the video, keeping the audio, as I explained above?

Thank you!

Jan Gruuthuse

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Re: Editing: Blank video but keep audio but in a section
« Reply #1 on: August 10, 2015, 03:36:42 PM »
While re-encoding video with fade (in/out). Video-output select encoding like: Mpeg4 AVC
Filters: Transform: Fade
 1st: fade out: set start time, set end time
 2nd: fade in: set start time, set end time
Overlap both where you want full black.
Try with a small video 1st, to get a feel of it. See: small sample
No idea how long you could create black screen this way (duration)



« Last Edit: September 15, 2015, 10:42:56 AM by Jan Gruuthuse »

douche

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Re: Editing: Blank video but keep audio but in a section
« Reply #2 on: August 12, 2015, 06:42:16 PM »
Hello.

thank you so much for your help. I've been playing around with your tips, getting some good results, and also some not-so-good results.

Just like you wrote, the problem is the duration of the "black-out". I always have to make the fade-out "compete" with the fade-in as they overlap, so it is quite hard to get full-black where I really want it, and make it last more than a few seconds.

I tried playing with other filters (like "blacken borders", with borders filling the entire screen), but most filters don't use start and end time parameters. The "partial" filter option is also not working - a known bug, from what I gather. So  I'm left with the option of spliiting the video in three segments, then filtering the middle section, then appending them all back together - but this is a nuisance!

I was wondering if a different approach would work: making an auxiliary video with, say, 10 seconds of black and no audio, and then somehow pasting this over a segment of my original video... is this possible with Avidemux?

Thanks!

mean

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Re: Editing: Blank video but keep audio but in a section
« Reply #3 on: August 13, 2015, 05:52:26 AM »
If you are in no hurry, maybe better to wait a few days for the partial filter to be back

Jan Gruuthuse

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Re: Editing: Blank video but keep audio but in a section
« Reply #4 on: August 13, 2015, 09:57:51 AM »
I was wondering if a different approach would work: making an auxiliary video with, say, 10 seconds of black and no audio, and then somehow pasting this over a segment of my original video... is this possible with Avidemux?
This was the 1st path I looked at. The problem is here to match exactly the video/audio codecs encoding between the different parts. It was/is nearly impossible to do so.
Better option:
If you are in no hurry, maybe better to wait a few days for the partial filter to be back
If urgent: overlap additional fade out / fade in, shifted in time. You can add several at the same pass, I think: not tested by myself.
Fade out to the point where you want black, then fade in from there to where you want picture back.
« Last Edit: August 13, 2015, 10:51:38 AM by Jan Gruuthuse »

douche

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Re: Editing: Blank video but keep audio but in a section
« Reply #5 on: August 13, 2015, 11:20:31 AM »
If you are in no hurry, maybe better to wait a few days for the partial filter to be back
No, I don't have any special hurry, so I'll happily wait.

Where should I look for the new version with the bugfix? Is it some beta or will it come out at the sourceforge site?
http://sourceforge.net/projects/avidemux/

Thank you and thanks also to Jan.

Jan Gruuthuse

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Re: Editing: Blank video but keep audio but in a section
« Reply #6 on: August 13, 2015, 12:24:11 PM »
You're welcome, enjoy avidemux, all thanks to mean. I'm just a (enthusiastic) user ;) .
Info is found here: https://github.com/mean00?tab=activity
avidemux build: http://avidemux.org/nightly/ check the date!
possibly here: http://www.fosshub.com/Avidemux.html
« Last Edit: August 13, 2015, 12:26:46 PM by Jan Gruuthuse »

douche

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Re: Editing: Blank video but keep audio but in a section
« Reply #7 on: August 13, 2015, 07:18:11 PM »
Thanks for the links! I'll keep an eye on that.

This got me thinking of a more generic question. Shouldn't there be some sort of integration between the A-B marker system, and the filters? I mean, instead of the partial button, and having to define start and end markers (and deal with frame numbers or milliseconds), wouldn't it be better to make the filter work as part of the "Edit" menu, applying only to the currently defined section?

Lots of filters would benefit from this. But I don't know if it's too complicated to implement...

P.S.- at least the partial button could include an action to the get start and end positions from the A-B markers.

Jan Gruuthuse

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Re: Editing: Blank video but keep audio but in a section
« Reply #8 on: August 14, 2015, 12:09:08 AM »
I believe this is what mean refers to:
Quote
maybe better to wait a few days for the partial filter to be back

douche

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Re: Editing: Blank video but keep audio but in a section
« Reply #9 on: August 14, 2015, 11:28:25 AM »
Well, my only view into what the "Partial" option does in the filters (since it isn't working in my installation) are tutorials like this:
http://www.howtogeek.com/108584/how-to-quickly-edit-combine-transcode-apply-filters-to-videos-with-avidemux/
(see the "Filters" section)

It doesn't seem to be connected to the A-B markers used in the main UI of Avidemux...

douche

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Re: Editing: Blank video but keep audio but in a section
« Reply #10 on: September 12, 2015, 02:35:41 PM »
Hello,

I see we have a new version that came out a few days ago, 2.6.10 (150911_d8fa922130e).

I'm trying to run it to see if there is anything new regarding the topic of this thread. I see there is a checkbox under the A/B buttons saying "Play filtered", so we can see the video with the filters applied while playing it normally.

I don't see any "partial filter" button in the filters dialog box, though.

Am I missing something? Or is it just that this feature is still left for a future release?

Thanks in advance!

mean

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Re: Editing: Blank video but keep audio but in a section
« Reply #11 on: September 12, 2015, 02:40:37 PM »
Not done yet, after looking into it, it's complicated to do that i thought

Jan Gruuthuse

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Re: Editing: Blank video but keep audio but in a section
« Reply #12 on: September 13, 2015, 09:55:43 AM »
And implementing in fade (in/out) the 3rd option fade: "Black to Black".
As you have the skeleton already there?
Going from picture to black
Going from black to picture
and now starting black, staying black, ending black?
If I'm not viewing this to simplified.

@douche
[ ] Played filtered, is already there some time on avidemux main surface.

Jan Gruuthuse

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Re: Editing: Blank video but keep audio but in a section
« Reply #13 on: September 13, 2015, 01:06:57 PM »
Build. Installed  and tested.
@douche: You're Gonna Like This One.
« Last Edit: September 13, 2015, 01:54:19 PM by Jan Gruuthuse »

Jan Gruuthuse

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Re: Editing: Blank video but keep audio but in a section
« Reply #14 on: September 13, 2015, 01:38:22 PM »
Wow, wonderful, works great, as expected.
Small sample done with my 3sat demo mpeg-ts (most of you already know by now)
Blacked Out <- play or download in dropbox (45 MB +-)
Without blackout <- play or download in dropbox (69 Mb)
New video filter Black introduced by mean:
probably windows 32/64-bit already available in http://avidemux.org/nightly/
« Last Edit: September 15, 2015, 10:36:50 AM by Jan Gruuthuse »