Surround Sound setup - Mac Pro

[Darren Fry]

Hi All

We have a 6 projector setup in the pipeline - 2 x 3 projector edge blends - one of which has a 5.1 surround track accompanying it.

The surround system is a Yamaha YHT2910 - regular domestic type job and has a Digital Optical input.  I assume that it isn't as easy as plugging an optical cable out of the (new model) Mac Pro and into this amp to get the 5.1 surround out of Qlab?  My understanding is that the Digital Optical is 2 channels of audio that is encoded - presumably Qlab will not play this encoded file as an audio track?  The amp does not accept 5.1 analogue audio in.

So - please suggest a way to get 5.1 out of Qlab and into this system!  Converters would not be a problem if required but we would like to the keep the cost down if possible.  This is a custom created soundtrack so any advice on what format we will require this in it would be great.

Thanks in advance!

Darren

[Paul Gotch]

On 22 Jan 2015, at 14:56, Darren Fry <darre...@mac.com> wrote:

So - please suggest a way to get 5.1 out of Qlab and into this system!  Converters would not be a problem if required but we would like to the keep the cost down if possible.  This is a custom created soundtrack so any advice on what format we will require this in it would be great.

Things like QuickTime Player and VLC can output non audio streams via the toslink output. I don't know if QLAB can but I would guess not.

I'm not sure if this is still true but certainly at one point Qlab could only cope with playback of discrete stereo tracks in videos.

I suspect if I was doing this I'd use something else to play the video and control it from qlab with scripts.

-p

[micpool]

On Thursday, January 22, 2015 at 2:56:04 PM UTC, Darren Fry wrote:

>
> We have a 6 projector setup in the pipeline - 2 x 3 projector edge blends - one of which has a 5.1 surround track accompanying it.
>

I don't quite follow, one of what has a 5.1 soundtrack? Do you mean you are playing a video file from Qlab with 6 channel audio? . In which case what is the format of the video file and its audio tracks?


Mic

[Chris Ashworth]

On January 22, 2015 at 11:09:01 AM, Paul Gotch (pa...@chiark.greenend.org.uk) wrote:

I'm not sure if this is still true but certainly at one point Qlab could only cope with playback of discrete stereo tracks in videos.

That was v1 era; since v2 it plays back multiple (discrete) audio tracks in video files.

-C

[Sam Kusnetz]

Just to elaborate a bit on Chris' post:

QLab 3 can only access the first track in a video. That track can
contain up to sixteen channels of audio.

A 5.1 surround mix is sometimes encoded as channels in one track, in
which case it's no problem. But it's sometimes encoded as six tracks
with one channel each, in which case QLab will only play the first track.

If you're using Final Cut Pro, you can set your project to surround
sound and drop in multichannel AIFF or WAV files and they will correctly
appear as multiple channels in one track.

Cheerio
Sam
--
Sam Kusnetz | Figure 53 Field Operative
s...@figure53.com

[Darren Fry]

Thanks for all the replies so far.

So the setup is 2 edge blended projection screens (3 projectors on each screen) with 2 videos - 1 per screen and only 1 has audio. All run simultaneously from the same machine

So running a video from a third party application is out as qlab has to handle the blend but I guess we could trigger the audio from a separate application and get it synced up?

Does anyone know if qlab will play an encoded surround audio track so we can utilise the optical out?
Darren

[micpool]

Qlab will not play files with  AC3 audio

Even if it could it wouldn't be a good idea as passing a bitstream that requires subsequent decoding through any audio processing is a bad idea.

Qlab will play files with 5.1 audio (or any other format) if the audio is interleaved and is the first track in the Quicktime audio container

You can convert a movie with an AC3  soundtrack into a format Qlab will play by using the export in Quicktime Player

So you now have a file Qlab will play to 6 discrete audio outputs on an interface

An option for getting this into your Yamaha  Home Cinema setup might  be HDMI.  Getting audio in the correct format to replay over HDMI can be quite troublesome, but I have a Mac Mini 2011 and a Pioneer VLX70 AV Receiver in my lounge and Qlab will play 8 channels of audio through it using the HDMI connection from the Mac Mini. Open Audio Midi Setup and setup an HDMI audio output which you can map in the speaker set up page. You can click each speaker to play pink noise out of each output for testing

Select HDMI as the Qlab output patch

On the AV receiver switch through the audio input formats to find one that works. This might no be the most obvious on my Receiver it's Digital rather than HDMI.

The thing with HDMI is that there are so many variants of input output and connections, plus copy protection and other complications that the only way to know for sure if 2 pieces of equipment are going to work fully is to test it out.

If you can't connect over HDMI then I can't see another way of getting audio in to that amp as it lacks Multi audio in. Having said that, if you have a new MacPro, 6 projectors, and all the signal distribution to feed them, a cheap domestic Home Cinema system doesn't really seem commensurate with the investment you have made in the rest of the system. A proper audio interface, 6 channel amplifier and decent speakers might be a better idea.

Mic

[micpool]

And if you need a test video  file with AC3 I use the Alcorn McBride AC3 Test Clip (HD) one as it is very clear

http://www.alcorn.com/ftp/media/

Mic

[Darren Fry]

Amazing response!  Thanks that has answered everything very clearly :)

Agreed in terms of the system being quite domestic - I have been drafted in at the last minute as the previous setup was not suitable - a good learning curve for all though!

Anyhow, thanks again - I am looking forward to getting onto it and testing :)

[mick...@gmail.com]

Hi darren

> Does anyone know if qlab will play an encoded surround audio track so we can utilise the optical out?
> Darren

sorry for delay in picking up on this but qlab 2 will output ac3 files using the Perian components for
quicktime. Ive had to do it a few times and found that Perian by default will access multiple outputs via a
soundcard allowing 5.1 AC3 audio to be mixed on its own and from video files. With a little tweak of
the Perian pref file iot qlab2 can also output ac3 as a dolby digital stream to cheap home cinema systems
as I was asked to do once for a gallery install using composed ac3 audio.

There a few caveats as It wont do both full audio and ac3 reliably while set for digital and of course without the digital
Perian preference all ac3s sound like grating metal on the mac. It is also a bit flakey pastry doing setups and getting smapole rates correct
but once working with any time delays accounted for it ran smoothly for days (note days not weeks once it drops out a complete reboot
is needed.) With digital outputs volume fades are also a bad idea as the reciever can change its mind what its recieving
and i never found one that would just lock onto "dolby digital" they all had auto settings.

I used Snowleopard for this and was surprised that it still works in Mavericks exactly the same but of course qlab3
just spits back ac3 files as I guess avfoundation "says no". There are also some open source developments of Perian
which I havent tried yet but i imagine its only quicktoime based. I also can find only the Neyrink ac3 encoder for protools
which is a bit surprising expensive.

I can see for video you'll need qlab3 but wonder outloud if qlab2 and 3 will run synced together on the same mac given the different audio
and video engines they use ora macmini could the audio? I do have a bunch of links on another machine if youre still toying with the idea

And I know for qlab always say no to compressed audio

mick