[Kdenlive-devel] possibly impossible feature request - multichannel preview

[Dan Dennedy]

Hey
On Thu, Mar 6, 2008 at 8:06 AM, robcanning <robcanning at eircom.net> wrote:
> Dan Dennedy wrote:
>  > On Tue, Mar 4, 2008 at 2:32 AM, robcanning <robcanning at eircom.net> wrote:
>  >>
>  >>  i am currently working on a multichannel video installation using
>  >>  kdenlive and four different projectors playing four synchronized films
[...]
>  > used with SDI boards. However, you might be able to get multiple SDI
>  > outputs working as a poor man's solution.
>
>  (did you mean multiple SDI outputs as a poor mans solution or something
>  else? multiple sdis seem kinda rich mans solution no?)

Heh, dangit, SDL and SDI are so similar to each other! I meant
multiple SDL output as the poor man's solution. :-)

>  i thought there might be an easy solution for this but it seems not.
>  I'm quite happy to forget about monitoring the 4 outputs during the
>  composition of the piece and just focus on frame accurate synched
>  playback of the final rendered files.
>  i was looking at ivysync http://montevideo.dyne.org/wiki/IvySync which
>  says it can sync upto 4 mpeg2 files out  IvyTV <http://ivtv.sf.net>
>  supported hardware decoders

You could also do something using DV and firewire DV/analog
converters. The project sponsor of MLT first sponsored my development
of dv1394d, which is the foundation of the miracle video server
software I described. Either a MPEG-2 or DV solution would require
everything to be pre-encoded, which is a drawback and why MLT and
miracle were developed. At the moment, neither dv1394d or miracle have
a way to simultaneously start playback of multiple units, but within a
matter of a second, it should be possible to send the play command to
each unit. It would also be trivial to add a new command to do this.

>  i think maybe ivysync maybe a good solution but if anyone can think of a
>  better way i'm all ears :)

DV over FireWire has a little "warmup" time for the device to lock on.
There might be less accuracy in a DV-based solution than the ivysync
one. Also, you should know that the developer of IvySync, Jaromil, has
recently started hacking with MLT.

Hmm, doing a little research on ivtv, and I see there is a framebuffer
kernel module and an X driver with XVideo support. Also, I wonder if
it possible to direct the XVideo of certain video display cards to its
TV-Out. I had a feature on my old Matrox card and Windows driver to do
that. It could take whatever was sent to DirectDraw video overlay and
send that alone to the TV-Out. Jaromil should know more about this. It
would be interesting to add ivtv compatibility to MLT and IvySync-like
behaviour to Miracle.

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