Re: Question about CoreAudio, digital output out and multichannels audio
Re: Question about CoreAudio, digital output out and multichannels audio
- Subject: Re: Question about CoreAudio, digital output out and multichannels audio
- From: Jean-Yves Avenard <email@hidden>
- Date: Thu, 03 Mar 2011 00:49:25 +1100
Hi again
On 02/03/2011, at 6:15 PM, Jean-Yves Avenard wrote:
> When it comes to playing stereo audio and AC3 or DTS digital audio ; there's no problem whatsoever. Everything works according to plan, and this has been working fine for several years.
>
> When multi-channels audio however, not quite.
>
> when using the DisplayPort -> HDMI adapter (with audio support obviously).
> In either analog or digital mode :
> The AudioDeviceID only reports 2 and 8 channels as being available
>
> Is it expected for CoreAudio to only supports explicitly those? or can I assume that if 8 channels is supported then anything in between is also supported? (in particular 6 channels)
>
> In analog mode; even though I open the audio stream with 8 channels; and no error occurred. My amplifier shows that it's only getting 2 channel PCM. And effectively, writing some audio samples for each speaker on all 8 channels and getting CoreAudio to play it; only the front and left can be heard.
Looking even further into this; I found looking into "Audio MIDI Setup" ; that the HDMI output is automatically set as 2 channels audio.
If I set it to 8 channels ; then sure enough I get 8 channels audio.
However, as soon as I output digital audio, it reset to 2 channels again.
How can I programatically set the hdmi (or default audio output) to be 8 channels or 2 channels ?
I know how to set the number of channels per frame, but that is irrelevant to the problem at hand.
Thanks
JY _______________________________________________
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