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Choppy preview and output on fast machine

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Wed, 08/29/2012 - 22:00
#1
getut
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Choppy preview and output on fast machine

Please help, I am having a hell of a time getting Kdenlive to output a non-choppy video on my very fast computer running Linux Mint 13 and Nvidia proprietary video drivers. Its a 6 core I7 extreme with 16GB RAM, but yet the preview screen in kdenlive and any output video is choppy... and maybe not so much choppy as it looks like it "surges". Even when viewed in VLC.

Viewing the source media is fine with no choppiness or surging. The source video are 720x480 vob files straight from a DVD. They do have an odd framerate though. I think it was 24.0635 frames per second. It complains about no matching profile when I bring in my two video clips.

Is it possible that the mismatch between profile framerate and source framerate is the cause? I've tried creating a new profile, but I can't create anything but whole number values when I try to create the profile.

I have verified the behaviour on a Mint 13 Core I7 laptop also. I get the exact same thing.

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Sun, 09/02/2012 - 18:34
#2
getut
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Re: Choppy preview and output on fast machine

Please someone help me figure this one out. I have put a 60MB clip of the problem video up. My wife works in a Church office and simply has to splice a couple of these clips together for a lesson. We own the DVD the clips come from and also got permission for the re-ordering of the clips so no violations in any way here.

Anything we do to these clips other than simply copy the streams causes surging when watching it.

Here is the link:
http://www.pra13.org/vid.mpeg

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Mon, 09/03/2012 - 09:25
#3
normcross
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Re: Choppy preview and output on fast machine

I couldn't watch it streaming so I downloaded. Hope that's ok. I have a fix but I will have to explain tomorrow. At the moment, kdenline states the vid is 1min 15s.....VLC say 47sec and two other programmes say 1min.

Let's settle on 1min.

The reason for the delay. I like to pour myself a glass of wine when I see problems like this and it took two glasses+ to come up with a workaround.

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Sun, 09/02/2012 - 21:45
#4
getut
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Re: Choppy preview and output on fast machine

Your post made me smile. I'll wait patiently on the workaround. Based on how long I've been reading on this one I kind of got the impression that it was something wonky with the souce video.

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Sun, 09/02/2012 - 23:26
#5
yellow
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Re: Choppy preview and output on fast machine

Looks like a problem with pulldown.

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Mon, 09/03/2012 - 09:28
#6
normcross
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Re: Choppy preview and output on fast machine

Hi yellow, You've now got me scratching my head. What do you mean by "pulldown"?

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Mon, 09/03/2012 - 16:24
#7
normcross
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Re: Choppy preview and output on fast machine

@getut
The software I used last night, called Shotcut, would have to be built manually for use in Mint, so that's not the best option I suppose. Today I tried 'HandBrake', more widely known, and it worked fine. It just encoded your video into a .mp4 which then played well in Kdenlive.

I've never tried Mint, so see if you can install 'HandBrake'

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Mon, 09/03/2012 - 21:44
#8
yellow
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Re: Choppy preview and output on fast machine

hi normcross, here's a link:

http://en.wikipedia.org/wiki/Telecine

When I play the file through dgmpgdec. http://neuron2.net/dgmpgdec/dgmpgdec.html

It reports:

MPEG2 PS, 720x480 widescreen 16:9, 29.970030 fps, Video Type FILM, progressive Frame, SMPTE 170M

Mediainfo reports the sample file as 23.976fps NTSC Progressive with 2:3 Pulldown scan order. So my understanding was that depending on just how the source has been encoded inverse telecine may be required on the file for accurate editing / playback.

Luckily I'm too young to have come across much of that mangled mess. :-) So not that sure of the ins and outs, soft pull down, pull up, progressive mixed with interlaced and all that guff. :-)

Of coarse I'm not commenting on the quality of getut's source file just the antiquated methods it appears to have been originally encoded with, luckily things have moved on. :-)

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Tue, 09/04/2012 - 03:39
#9
getut
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Re: Choppy preview and output on fast machine

I'll try handbrake tomorrow, but can someone please give a layman's description of what the problem is and why Kdenlive isn't handling it? And maybe hopefully about what handbrake or other working program is doing to correct the problem with my source video.

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Tue, 09/04/2012 - 17:18
#10
normcross
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Re: Choppy preview and output on fast machine

Hi yellow, That made very interesting reading, now I have a better insight at the trickery going on in the background.

Back to getut's video. Nothing seems to see it the same.

Nautilus says 30 f/ps......time 1 min 15sec long
Vlc says 59.94 f/ps......time 47 sec long
HandBrake says 23.97 f/ps.....time 1 min 13 sec
Kdenlive say 24.06xx f/ps....time 1 min 15 sec
Shotcut say 30 f/ps.... time 1 min 2 sec.

Kdenlive show 7/8 video frames and then 6 static frames recurring.

So, when you say:-
......... "just the antiquated methods it appears to have been originally encoded with, luckily things have moved on. :-)" there's not much that can be done.

Hi getut,
As you just wants to join the clips, I would stay with running them through HandBrake and then importing them into kdenlive. Clips cut ok and a test render played fine.

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Tue, 09/04/2012 - 23:36
#11
yellow
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Re: Choppy preview and output on fast machine

hi normcross, a quick remux with mkvmergegui into a mkv container seems to have done the trick for me with the sample. A/V appears to stay sync'd and no stuttering frames.

http://www.bunkus.org/videotools/mkvtoolnix/

I was using the PPA I think.

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