[vlc-devel] Re: [MOD] Mac OSX multichannel patch

Jean-Alexis Montignies ja at sente.ch
Fri Jun 4 12:03:17 CEST 2004

Hi Matt (and all folks),

I think I'm the last one to have patched coreaudio.c. I've just changed 
the code so that it works with other streams than the first one. In my 
idea, it was a quick patch.

There is a right and easiest solution for making it work in all cases 
(at least for a single interface) and have the user being able to map 
the channels.
It is to use the HALAudioOutputUnit of core audio which does all 
conversion/mapping/interleaving for you.

Now, another problem of VLC is that it decides which kind of surround 
to use depending on the number of channels you have on the interface. 
So if you have a 20 channels interface, it could be lost or output to 8 
channels, even if you have less speakers (let's say 4 or 5 for 
instance) connected.

Any idea on where to select the surround setup.

I've tried in the audio-channels menu, but my code just don't work for 
ouputs with more than 2 channels (even the left/right selection in the 
repository code doesn't work on more than stereo interfaces). Any ideas 

Jean-Alexis Montignies

On 4 juin 04, at 10:52, System administration wrote:

>  The deleted attachment is at:
>     <http://www.videolan.org/~admin/20040604-videolan/coreaudio.c>
> -- 
> System administration <admin at via.ecp.fr>
> VIA, Ecole Centrale Paris, France
> From: Matthew Romaine <Matthew.Romaine at jp.sony.com>
> Date: 3 juin 2004 15:06:14 GMT+02:00
> To: vlc-devel at videolan.org
> Subject: [vlc-devel] Mac OSX multichannel patch
> Hi folks.
> I have preliminary multichannel support working on OSX.  Unfortunately 
> I don't have svn working to make a patch, so here's the complete 
> coreaudio.c module.  I worked off the -20040524 snapshot, which still 
> seems to be the most current one.
> Many comments in the code to help figure out what's going on.  
> Basically what needed to happen was support for deinterleaved streams. 
>  Devices that had a single stream with multiple channels were easy 
> (such as most MOTU devices), but there are a few devices out there 
> that have multiple single-channel streams that need to be grouped 
> together for multichannel support, such as the RME Hammerfall.
> At some point in the future it might be nice to let users select or 
> map channels in a more adhoc fashion, or at least choose which 
> groupings they'd like to use (for example, when multiple devices 
> support multichannel...)
> maybe it's already implemented; i haven't figured out the whole VLC 
> interface; too many options :)
> The only serious bug I came across so far was when I detached an 
> unused device while playing through another one.  Basically the 
> DeviceListener callback needs to be looked at I think.
> Also, I have not tested any of the SPDIF/AC3 sections, as I don't have 
> the resources currently to do so.  Please check them, if you can.
> Anyways, if the attached is integrated, could someone please update 
> the snapshots directory?
> thanks,
> matt
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