[Kdenlive-devel] quick question

Dan Dennedy dan at dennedy.org
Mon Dec 7 04:03:02 UTC 2009

2009/12/6 Evert Vorster <evorster at gmail.com>:
> I still have no Qimage support in kdenlive.
> How does MLT/kdenlive figure out what is supported?

Each module has a configure sh script. Most of them are fairly readable.

> I found a bug that sounds similar to my kdenlive crashing when I want to add
> a title clip, and since kdenlive shows me I have no QImage support, I think
> it's all related.


> kdenlive does not show up on the "melt -query producers" list.
> I think I should have qimage support, though, and I'm just going through the
> documentation now.
> grepping through the compile/install logs of mlt, I can see both the qimage
> and kdenlive modules built and installed:

Yes, I agree from the logs. More than likely, at run time ld.so can
not locate the qt libs. 'ldd /usr/lib/mlt/libmltqimage.so' will help
you determine that.

> So my only question here is how do I tell MLT that the qimage/kdenlive
> packages are installed?

ld.so uses /etc/ld.so.conf and LD_LIBRARY_PATH environment var.

> Sorry, Dan, you asked me how I did the "transcode" earlier.
> I meant I was able to pull an AVCHD clip into kdenlive, and just render that
> one clip as x264 .mp4 file. Not much of a codec change, I know, but it ran
> through the encoder and decoder.

ok. If you right-click a clip in the Project Tree of Kdenlive, there
is a Transcode feature that uses ffmpeg alone. It uses presets
configurable in the Settings. We have a preset for DNxHD, which is
what worked for me on my transcode. DNxHD is near lossless.

Direct AVCHD is still a bit dicey. Where it does work rather well
(seems to depend on what camera it comes from), performance of
accurate seeking is painful. I only recently got gmerlin working here
to be able to judge its support for AVCHD and Ogg Theora (our other
popular problematic format). Indeed, it is quite nice for both, but it
is a major effort to integrate gmerlin-avdecoder, and it is a rather
large dependency stack that gets less distro maintainer attention
compared to another potentially large dependency stack - gstreamer.
So, using FFmpeg-alone is appealing as it has given us a lot but with
a small footprint. In 2009, with respect to AVCHD, we did at least
gain clean and accurate seeking and better seek performance was close
but not accepted due to regression or side effects. So, it made sense
to wait and see how that work progressed. Now, the waiting is starting
to get long. But, I am also quite busy just maintaining what I already
do have to take on gmerlin-avdecoder or gstreamer at this time.


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