[kdenlive] FW: KDENLIVE 0.9.10 Very Slow Rendering

[Dan Dennedy]

On Fri, Jan 23, 2015 at 9:28 AM, jb <jb at kdenlive.org> wrote:

> Hello,
>
> > Hi,
> > I recently had a major problem after upgrading from 0.9.6 to 0.9.10 using
> > Ubuntu 12.04
> >
> > I finished up spending about 2 weeks backing up, restoring, changing to
> > Ubuntu 14.04 hoping that would solve the problem but it didn't.
> >
> > What I found was that everything worked fine with 0.9.6 but rendering
> small
> > clips with 0.9.10 took twice the time. Larger clips just seemed to clog
> up
> > and die.
> >
> > After a lot of investigation I found out that it is the MLT rendering
> > profiles which are causing the problems. In 0.9.6 the typical profile for
> > an MPEG2 file render was :-
> >
> >
> > f=mpeg acodec=mp2 ab=%audiobitrate+'k' ar=48000 vcodec=mpeg2video
> minrate=0
> > vb=%bitrate+'k' bf=2 b_strategy=1 trellis=1 aspect=%dar pass=%passesWhere
> > in 0.9.10 the number of profiles was significantly reduced and the number
> > of parameters has substantially reduced, the main culprit being the
> > replacement 0f "f=mpeg" for "properties = MPEG-2" or something like
> that, I
> > no longer have 0.9.10 loaded having gone back to 0.9.6 so I cant remember
> > exactly what the MLT parameters are.
> >
> > The main problem is that the new profile takes at least twice as long to
> > render, but when the script is running it provides an estimated time
> > remaing which counts down (slowly) and then seems to stop at just a few
> > seconds remaining or 0 remaining where it sits for about the same time
> > again as the rendering all ready took. For short clips this is just an
> > incovenience but for longer clips it can sit there apparently frozen for
> > hours.
>
> Maintaining profiles for the many file formats supported by Kdenlive is
> not an
> easy task. So at some point, before the 0.9.10 release, it was decided to
> switch to the profiles provided by MLT with some minor customization.
>
> The MLT presets are simple text files with FFmpeg properties, that are
> installed in:
> $INSTALL_DIR/share/mlt/presets/consumer/avformat
>
> I did some tests with the MPEG-2 profile, and you are right, it takes
> almost
> twice the time to render, compared to the older settings.
>
> The difference is in some parameters set in the MLT preset:
> mbd=rd
> cmp=satd
> subcmp=satd
>
> This is probably supposed to enhance quality, but as you noticed, you can
>
>
yes
http://www.ffmpeg.org/faq.html#Which-are-good-parameters-for-encoding-high-quality-MPEG_002d1_002fMPEG_002d2_003f

-- 
+-DRD-+
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