Linking 2 powerbooks to synch H.264 720P playback?

Aug 6, 2006 at 8:26pm

Linking 2 powerbooks to synch H.264 720P playback?

I’m producing several stereoscopic films in 720P at 24 fps. In order to project them for audiences, I need to synchronize fullscreen QuickTime playback (in 24 FPS, 720P H.264) from 2 powerbooks or the dual DVI outputs from a Power Mac G5. This is currently a stumbling block that I’m trying to overcome in order to develop a platform for lowcost, immersive, HD sterescopic film presentation. I’m looking for a simple solution that doesn’t require a huge software programming or development effort. I’ve tried some of the obvious solutions; setting a time for 2 QT windows to launch and play, spreading one large QT movie over 2 screens and cropping the controls, etc. None so far have been frame accurate enough. I really need the playback to be absolutely frame accurate (at least to the frame level, 1/24th of a second). I would love to have this on a G5 (or dual powerbooks is another possibility), since my entire workflow is Mac and QuickTime is a lot nicer to work with.

Can Jitter and Max do this? Anyone know of any other way?

Just getting frame accurate playback of 2 HD QuickTime streams from the dual DVI outputs of an NVIDIA card in a G5 would be a huge leap forward….
Here?s a test movie that I made (very compressed!!)

http://www.emoclients.com/3d/paris.mov

#27056
Aug 6, 2006 at 9:43pm

Just recently I synced 4 laptops playing HD quicktime movies by using a 1
master and 3 slave setup. All laptops used a simple qt player patch, but
instead of letting jit.qt.movie playback using the “play” message, I
triggered each frame by number, using the “frame” message. The master had a
clock + counter sending the framenumbers over a network, using mxj.maxhole.
The only problem I had was that the rather old ibooks couldn’t handle all
parts of my movies at 24fps. Other than that the syncing worked fine.

hth, -thijs

On 8/6/06, Paul Lundahl

wrote:
>
>
> I’m producing several stereoscopic films in 720P at 24 fps. In order to
> project them for audiences, I need to synchronize fullscreen QuickTime
> playback (in 24 FPS, 720P H.264) from 2 powerbooks or the dual DVI outputs
> from a Power Mac G5. This is currently a stumbling block that I’m trying to
> overcome in order to develop a platform for lowcost, immersive, HD
> sterescopic film presentation. I’m looking for a simple solution that
> doesn’t require a huge software programming or development effort. I’ve
> tried some of the obvious solutions; setting a time for 2 QT windows to
> launch and play, spreading one large QT movie over 2 screens and cropping
> the controls, etc. None so far have been frame accurate enough. I really
> need the playback to be absolutely frame accurate (at least to the frame
> level, 1/24th of a second). I would love to have this on a G5 (or dual
> powerbooks is another possibility), since my entire workflow is Mac and
> QuickTime is a lot nicer to work with.
>
> Can Jitter and Max do this? Anyone know of any other way?
>
> Just getting frame accurate playback of 2 HD QuickTime streams from the
> dual DVI outputs of an NVIDIA card in a G5 would be a huge leap forward….
> Here?s a test movie that I made (very compressed!!)
> http://www.emoclients.com/3d/paris.mov
>

#81498
Aug 7, 2006 at 12:11am

Thank you for the prompt feedback!!
Dumb question, what do I need to do this?
Max, Jitter and any hardware?
Is there a script that runs it all?

I?m clueless as regards to Max, any direction would be appreciated.

Thanks in advance.

Cheers,

Paul

#81499
Aug 7, 2006 at 8:25am

I was about to make a suggestion but looking at your exerpt, you already do that…
make one video out of your left and right eyes, like in the one posted on the website.
It s the best thing to do if you do the thing with one computer.
Then you have several choices.
First, a good hardware solution for its simplicity: the dualhead2go from matrox.
have a look here http://www.matrox.com/mga/offhome/dh2go/home.cfm
with this box you only need qtplayer pro (or VLC, though i m not sure it recognizes the H264) to
play your movie in full screen mode.
The two sides will automaticly be sent to the two monitors connected to the dualhead2go.
the second “way” is to use jitter to spread a jit.window across two screens (pay attention to the
fact that not all graphic cards allow openGL accel on two cards, but Nvidia’s do… I guess) and
use a jit.qt.movie connected to a jit.videoplane, addapt the scalling correctly and there you go.
If I were you, I d go for the dualhead2go, it realy is interesting for synching two
streams…and especialy if you have no knowledge of max it will save you a lot of time.

salut!
//yac

#81500
Aug 7, 2006 at 2:57pm

On 8/7/06, Paul Lundahl

wrote:
>
>
> Thank you for the prompt feedback!!
> Dumb question, what do I need to do this?
> Max, Jitter and any hardware?

You’ll need max + jitter. setup a simple network using a hub for example.
Make a simple patch with the mxj net.maxhole object in it. It will output
any message you put in, on all max instances that are on the same network.
Simply send the framenumbers from your counter into maxhole and use the
output on all computers to trigger the video in your jit.qt.movie. You’ll
have to follow the “frame n” messages by a bang to output each frame. Check
the helpfiles of jit.qt.player and mxj net.maxhole for details.

-thijs

#81501

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