Tuning struggles

Here you can ask your questions on how to use Comskip for the detection of commercials. Also questions on how to remove commercials are welcome
djtaylor
Posts: 8
Joined: Mon Feb 13, 2006 8:23 pm

Tuning struggles

Post by djtaylor »

Hi

I know you're going to ask for the set of files but before we get that far, i'm happy to play a while but it seems that the issue is that US shows have a nicely formatted start/end to commercials (I may be wrong?)

I have had little success getting any general settings to work well in the UK, we seem to have some shows with logos, some without, some where there's a stupid sponsor message after the logos and before the show. Some where they'll go straight to the show after the commercials with no nice black frame etc.

No matter what I try for the segment lengths, Comskip just isn't finding blocks that fit nicely to the programme.

Also, I have one show where there is a nice logo during the show but not the adverts and I can't get sensible detection there either. In the gbpvr forum, you posted about changing the maxvolume but after much playing around with that, i'm getting no success there either.

It would help if you could provide some workflow tips as to how you go about fine tuning because yes, i've read the docs, i've tried to pick up what I can but you must have a methodology yet all I can find tends to drift quickly to here are the settings, play around with them to make it work!

Thanks
David.
erik
Site Admin
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Joined: Sun Aug 21, 2005 3:49 pm

Post by erik »

Just to make you happy, there are channels on which comskip will never be able to do a decent job.

First is to get the silences detected.
There is little reason why setting max_volume=500 will not work.

Next set max_avg_brightness=25 and see if there are black frames found.

If you send me the .csv file I will have a look for your and suggest settings for these two values.

They should be channel independend because they depend on the quality of your antenne signal, the cvbs decoder and the settings of your mpeg encoder.
Once this is ok we can investigate what tricks should be used to get the maximum out of the .csv
djtaylor
Posts: 8
Joined: Mon Feb 13, 2006 8:23 pm

Post by djtaylor »

Thanks, here's the csv of one that should work well. It has logos during the show and I can see that the logo detection is working well when using debug mode, I just can't seem to get any sensible blocks set up with commercials.

You posted a nice tease for tipster in the gbpvr forums, i'm aiming for that result as a starter! :)

csv file on its way.

David.
erik
Site Admin
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Joined: Sun Aug 21, 2005 3:49 pm

Post by erik »

Its easy to see that
comskip -w filename.csv
Press F1 for help on the keys you can use.
Click anywhere on the timeline (top of the window) to quickly position.
erik
Site Admin
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Joined: Sun Aug 21, 2005 3:49 pm

Post by erik »

OK,

Very interresting recording, no black frames at the start of the commercial.
so we need to open the box of tricks.

Try to set
after_logo=5
and
max_commercialbreak=300
in the comskip.ini from the comskip distribution file.

The after_logo=5 is explained in the tuning.htm file.
Basically it will insert a cutpoint after 5 seconds after the logo disappears at the first silence found within 30 seconds.
WIll require some tuning.
djtaylor
Posts: 8
Joined: Mon Feb 13, 2006 8:23 pm

Post by djtaylor »

Thanks, that was much better.

I think if you can jot down a sticky with your basic workflow and tips under a variety of scenarios, you'll save yourself a lot of repeat answering.

I'll send you a harder one later ;)

Cheers
David.
erik
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Joined: Sun Aug 21, 2005 3:49 pm

Post by erik »

The tuning guide works well.
Its only the very exceptional cases like this (no black frames) that are insufficiently covered.
The bonus for me is that I receive the .csv files i can use for further enhancement.
djtaylor
Posts: 8
Joined: Mon Feb 13, 2006 8:23 pm

Post by djtaylor »

ok :)

I will have pleasure in sending you a few more from the UK over the coming weeks ;)

If it helps, I can host some sections of the difficult mpg's.

David.
djtaylor
Posts: 8
Joined: Mon Feb 13, 2006 8:23 pm

Post by djtaylor »

Ok, another csv on its way to you.

There's a clear aspect ratio change at frame 22730 (or thereabouts) then at the end of that commercial, back to the previous aspect ratio.

The programme then resumes at frame 28567.

What I don't understand is that there's a pink line at this change but the top grey bar spans this and part of the adverts.

I can't see anything obvious in the graphs as to how to either interpret the information in them nor what to change.

Any help appreciated once again. :)

David.
azuanaa
Posts: 1
Joined: Fri Feb 10, 2006 4:18 am

Post by azuanaa »

erik wrote: The after_logo=5 is explained in the tuning.htm file.
Basically it will insert a cutpoint after 5 seconds after the logo disappears at the first silence found within 30 seconds.
WIll require some tuning.
Hi erik,
I got almost the same problem as this, not black frame before commercial here in Malaysia. I also tried the after_logo and before_logo, and now I understand why the cutpoint is 11 second after the logo disappears, is it possible to just insert the cut point right after the logo disappears and not looking for the first silence. :)

TQ
azuanaa
erik
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Post by erik »

Not at the moment.
Should it actually be directly after the logo disappears?
Or is there a usable silence or other clue directly after the logo disapears?
Or is there a silence shortly before the logo disappears?

In the last situation you can use
shrink_logo=5
and
after_logo=3
to cut at the silence after 2 seconds before the logo disapears
erik
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Post by erik »

djtaylor wrote:Ok, another csv on its way to you.

There's a clear aspect ratio change at frame 22730 (or thereabouts) then at the end of that commercial, back to the previous aspect ratio.

The programme then resumes at frame 28567.

What I don't understand is that there's a pink line at this change but the top grey bar spans this and part of the adverts.

I can't see anything obvious in the graphs as to how to either interpret the information in them nor what to change.

Any help appreciated once again. :)

David.
I am making progres, but.
Is it possible to send an edited .txt file with the correct start and stop frame numbers of all the things you want to cut out?
Please change the extension to .ref so I know you did edit it.
Always send this together with a .csv file. It saves me a lot of work.
djtaylor
Posts: 8
Joined: Mon Feb 13, 2006 8:23 pm

Post by djtaylor »

files sent.

I created this text file manually because no matter which keys I pressed, i, b, e, w etc, nothing seemed to get written to the file.

What's the correct sequence of keys to use the commercial review?! :)

David.
erik
Site Admin
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Joined: Sun Aug 21, 2005 3:49 pm

Post by erik »

The editing only works when you start comskip on the .txt file so
comskip chicken.txt

With respect to the last csv file you did send, it is a very interresting recording you made. The ini file for this will be incompatible with many other channels......
Please try these changes w.r.t your default ini file

detect_method=47
cut_on_ar_change=2
delete_show_after_last_commercial=1

The cut_on_ar_change=2 is undocumented yet, ar cutting at 1 is normally disabled when no logo is found. Setting it to 2 means always cutting at ar change if there is a silence.

This is the first case where scene change detection did a good job, so thanks for this input.
djtaylor
Posts: 8
Joined: Mon Feb 13, 2006 8:23 pm

Post by djtaylor »

Understood about opening the txt file, i'll try that next time.

Unfortunately all those settings I already had. Probably not going to work too well on this one I guess?

Like I said, we have some evil scene changes with show going to animated full screen logo then fade to commercials with not a logo in sight.

Broadcasting gits! :)

David.
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