[mythtv-users] How to get 5.1 dts spdif out from ac3 sources?

Michael T. Dean mtdean at thirdcontact.com
Tue Jun 2 04:21:29 UTC 2009

On 06/01/2009 11:10 PM, Allen Edwards wrote:
> On Mon, Jun 1, 2009 at 7:33 PM, Richard Shaw wrote:
>> On Mon, Jun 1, 2009 at 2:48 PM, Harry Coin wrote:
>>> My second mistake was setting the 'maximum channels' to 5.1.   The correct
>>> choice for multichannel digital output is 'stereo'.  Why that is correct
>>> when I actually want and have 5.1 output is confusing.
>> I'll do my best to answer this part from previous posts I've read. I think
>> this only applies to analog out channels. When using digital audio, you only
>> ever have 2 real channels, it's just that the format (AC3 or DTS)
>> multiplexes the audio into 5.1 (6) or 6.1 (7) channels. I agree it's
>> confusing on the surface and I'm not sure that expecting the average user to
>> understand this is a good idea. I haven't messed with it lately but I know
>> that there is often additional info on the bottom of the setup screens. I
>> wonder if something to this affect could be added to clairify. I suppose
>> another option would be to add the logic to Myth to have it make the right
>> choice anyway since it must be set to 2 channels for digital audio.
> The 5.1 option is broken and should never be selected.  Read my wiki.

Better stated, the 5.1 option is meant for /analog/ output *only* as 
S/PDIF is inherently 2-channel (or non-audio) and has no support for 5.1 
channels (AC-3 and DTS are non-audio data, so channels don't apply).

Richard's answer is correct.


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