[Kdenlive-devel] Hi there!

Evert Vorster evorster at gmail.com
Sun Dec 6 23:22:53 UTC 2009


Yup...

The way I produce this error directly is to have one AVCHD clip that playes
for the whole time...

Then I have have another clip that I put and "in-time" and an "Out-time"
through the clip window, and drag it to be above the one longer clip that is
already there.

The I crossfade and mute the new clip, so as to have the audio from the
longer clip and the video from the newer clip for a section.

The shorter, newer clip always plays at the wrong speed.

FYI, ffpeg still does not transcode AVCHD correctly...

when I issue:
ffmpeg -i file.mts file.mp4

What I expect is an mp4 of the same duration/resolution than the mts ( AVCHD
) file. The audio is the same duration, but the video plays at 50% of the
speed.
Of course, the bitrate is down to 200bps, so the video does not look too
good, but that does not matter in this case. It just highlights a bug.
I really have tried specifying frame rates of both input and output, but
nothing seems to convince ffmpeg that I really do have a video that is
recorded at 25fps with full hd.

I do not particularly like to transcode my source material, as you can never
get the quality back, but if I have to, I would use a tool like gmerlin,
which handles these files perfectly.

Thanks for all your help, btw.
Once the bugtracker accepts my application I'll do the bug reports properly.
Sorry for putting all this in the devel mailing list.

Kind regards,
-Evert Vorster-

On Sun, Dec 6, 2009 at 6:47 PM, Dan Dennedy <dan at dennedy.org> wrote:

> On Sun, Dec 6, 2009 at 12:40 PM, Dan Dennedy <dan at dennedy.org> wrote:
> > 2009/12/6 Evert Vorster <evorster at gmail.com>:
> >> Hi, thanks for the help. I was following that guide as closely as my
> distro
> >> allows.
> >>
> >> I think I got most parts of it working. ( No Qimage support yet, will
> get
> >> that tonight )
> >>
> >> Already I ran into a nasty bug. I reported this to the ffmpeg guys last
> >> year, but they just ignored it.
> >>
> >> I have a Canon HF100 HD recorder. I record in 1920x1080x25fps, but
> ffmpeg
> >> picks it up as 50fps.
> >
> > Just because it reports 50 fps does not mean that it will play at the
> > incorrect speed; it depends more on the timestamps.
> >
> >> This messes around transcoding and kdenlive. I can
> >> transcode a clip fine, but once I start slicing and dicing the clips
> some
> >
> > Please be more clear about how you did "transcode."
> >
> >> run at "double speed" on the video while their audio is running
> normally.
> >
> > I have some sample clips from the 50i/25p Canon HF100, and they work
> > fine here. I did not do extensive cutting or anything, however - just
> > playback in the Clip Monitor. Also, I tested the output of Kdenlive's
> > Transcode to DNxHD, which just runs ffmpeg as a child, and that works
> > fine as well. And I am confident that cutting on the DNxHD output will
> > not give altered playback rate (less confident about that when
> > directly using AVCHD).
>
> OK, I did just see the problem when cutting the AVCHD directly.
>
> --
> +-DRD-+
>
>
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