Live video sourced from another Mac

harrisonpault's picture

I want to source a video stream on one Mac and integrate it into a QC application on a second Mac. I have the general impression that the tools to do this are lying around, but I can't quite wrap my head around it. I am pretty sure that the way to get the stream between machines is TCP/IP. For the moment I am pretty sure I will be able to do wired 100Mb or 1Gb over CAT5. I also assume that this means an encode/decode process (pack it up as H.264, send it, reconstitute it).

I kind of get that, say Quicktime Broadcaster should let me stream a live DVCam or iSight (do the encode and send), and that a QC Video Input patch with the URL for the other machine's stream should pick it up (receive the packets and decode them) on the other end. Maybe this also needs a Quicktime Realtime Streaming Server?

But what if my source is a QC that is generating a video stream itself? Is there some way to make a QC consumer patch look like a DVCam to Quicktime Broadcaster? Or is there a plugin that takes an image as an input port and emits a TCP/IP stream like Quicktime Broadcaster? It seems that the QTKit or AVFoundation API's along with other standard XCode libraries ought to allow the creation of such a plug, but has anyone done it?

It also occurs to me that IF I had a 'Quicktime Broadcaster' plugin for QC, then I could marry it to a syphon client and kind of extend syphon over a network (with massive performance downgrade, of course). Any video source that could be served via syphon could be sent out over the local network and re-served with a video input patch married to a syphon server on a separate machine.

Anyway, how should I be doing this?

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Scratchpole's picture
Re: Live video sourced from another Mac

I think this should help you. http://kineme.net/wiki/StreamingQuartzComposer

harrisonpault's picture
Re: Live video sourced from another Mac

No, I've read through that wiki a few times, and searched the forums. But nothing seems to touch on the issue at hand: emitting video from one mac and retrieving it on another. Still looking for any ideas.

franz's picture
Re: Live video sourced from another Mac

video capture card is the safest/plug and play option

gtoledo3's picture
Re: Live video sourced from another Mac

I agree w/ franz. That said, there's an old project called "QuartzComposerTV". You might want to look at how it sets up the firewireDV out, and see if that can be mutated into your purposes.

Are you sure about the conclusions you're having with syphon though? My impression is that it's based on iosurface, and that it's about sharing resources that are already on a given computer/gpu. (On a similar note, there are good app examples at the ADC for this, with server and clients that actually let you choose which gpu they run on, if more than one is installed.)

cybero's picture
Re: Live video sourced from another Mac

@franz, any recommendations regarding the type / brand of video capture card? The Blackmagic range looks like it ought to be a very good fit.

gtoledo3's picture
Re: Live video sourced from another Mac

I'm not franz, but the blackmagic decklink is pretty popular/ok. You'd have to set QC to open in 32 bit mode and receive it with the video patch, or use some kind of custom patch.

franz's picture
Re: Live video sourced from another Mac

depends if you use a laptop or a desktop. I personally have a matrox mx02 --> crap and a decklink HD extreme --> good

The decklink intensity pro is also very good for the value.

They now make an Intensity Thunderbolt, suitable for laptops, which seems to be the way to go (untested tho', but i might get it at some point)

harrisonpault's picture
Re: Live video sourced from another Mac

That makes sense.

To be clear, you mean setup a video-out connection from machine 1 to the video input side of a capture device that is hosted by machine 2. Depending on the capture device and it's drivers it will appear as some sort of video input to machine 2, hopefully recognizable by a QC Video Input patch.

As one example, a Matrox MX02 Mini would take a machine 1 minidisplayport output (through an HDMI adapter) as input and connect to machine 2 with thunderbolt or express34 adapter to look like a connected video camera to machine 2?

Mind you, I am thinking non-MacPro-class Apple machines with no expansion slots for PCI cards.

Many of the capture devices on the market appear to be geared towards file ingest for later offline video editting. I mention the Matrox, because they articulate product usage for live streaming applications. Probably other manufacturers' products can also work in this fashion?

Paul

franz's picture
Re: Live video sourced from another Mac

totally correct.

However I wouldn't recommend the Matrox (it's a joke.. I had sooo many problems, faulty hardware, faulty drivers .. etc). Or maybe I was just unlucky ...

harrisonpault's picture
Re: Live video sourced from another Mac

Thanks for that suggestion. I also see that a LiveDV app was used back a while for doing this http://www.udart.dk/2009/07/30/the-5-video-mixer-how-to-do-a-dv-screen-c... So, as long as we are talking DVCam resolutions and codecs this is doable without the capture device in the middle. I will examine the QCTV / Quartz Composer TV developer example when I get a chance.

.lov.'s picture
Re: Live video sourced from another Mac

I'll get my hands on a Blackmagic Intensity Extreme in a week or so. I'll definitely try the Mac-to-Mac connection via HDMI+Thunderbolt - letting you know about the results if you guys are interested ;)

harrisonpault's picture
Re: Live video sourced from another Mac

Great. I would love to hear how it goes.

vade's picture
Re: Live video sourced from another Mac

It totally works well. There is some perceived latency though with all of these capture cards, but the Quality is very nice.

vade's picture
Re: Live video sourced from another Mac

The MXO2 Mini with the newer drivers is a lot better. It works pretty well, about on par with the Intensity to be fair. I just don't like the express card form factor.

franz's picture
Re: Live video sourced from another Mac

did some1 try QC-VNC plugin ?

https://github.com/mirek/quartzcomposer-vnc

.lov.'s picture
Re: Live video sourced from another Mac

So, I did some test since my Intensity Extreme card received :) First of all, the driver is buggy, I need to do a Log Out/In to make device working if I make a connect/reconnect between the device and the computer.

Anyway, I did NOT see any noticable latency when sending 1080p/720p from one Mac to another.

epochapex's picture
Re: Live video sourced from another Mac

I found this:

http://www.udart.dk/2009/07/30/the-5-video-mixer-how-to-do-a-dv-screen-c...

— How to connect two macs using firewire and QC screen capture patch.

I haven't tried it, but I hope it works for you.