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Short pauses after cuts

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Thu, 10/22/2009 - 18:59
Marko
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Joined: 10/22/2009
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Hello,

I am new to this forum. I have switched from Kino to Kdenlive as I upgraded from DV to HDV.

I have a strange problem: in the rendered video, and also on the project monitor, after each cut there is a varying small number of identical frames, giving a "freeze frame" effect for a fraction of a second.
I've already noticed this on v 0.74, now I have 0.76 and this has not changed.

It only happens with HDV, if I work with DV, this does not come up.

Like something to do with MPEG inter/infra frames???

Anybody else noticed this? I have opensuse 11.1 and have installed Kdenlive from the rpm repositories.

Marko Cebokli

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Thu, 10/29/2009 - 19:43
#1
Marko
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Re: Short pauses after cuts

Nobody else encountered this?

I tried SD MPEG files, and the results are OK.

So it seems that this problem only occurs when I edit HDV from my Canon HV30, and regardless of what output format I render to.

I have put a little example here:

http://lea.hamradio.si/~s57uuu/video/example.mpg

Marko Cebokli

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Tue, 11/03/2009 - 07:31
#2
ddennedy
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Re: Short pauses after cuts

It is a problem with using with open-GOP HDV.
See this bug: http://www.kdenlive.org/mantis/view.php?id=1216
You need to trim the ends to remove this.

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Sun, 11/08/2009 - 15:41
#3
Marko
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Joined: 10/22/2009
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Re: Short pauses after cuts

Thanks for the info!

I see now that if I trim the ends of the clips by ca 1 sec, things are OK.
So this means, that while shooting, apart from the 1..2 sec of "meat" that I provide for editing at each end, I should provide one second more for this....

Of course, this is impossible with existing clips... so I tried transcoding from "open GOP" to "closed GOP" like this:

mencoder infile.m2t -ovc lavc -lavcopts vcodec=mpeg2video:vbitrate=24000000:aspect=16/9 -oac copy -o outfile.mpg

This seems to work well, no more "freeze frame" effect on splices of untrimmed clips.

However, since the maximum bitrate you can specify to mencoder is 24Mbps, the output file is cca 20% smaller than the original, which I guess causes some quality loss... (although my squinty myopic eyes can't really see any difference).

Anyway, this is a clumsy workaround, so I still hope for a fix in Kdenlive... :-)

Marko Cebokli

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