[mythtv-users] additional configuration items for new sound system in 0.24

[Jean-Yves Avenard]

Hi

On 17 November 2010 00:00, Brian J. Murrell <brian at interlinx.bc.ca> wrote:

> Having played a bit with the new sound system in 0.24, I have to say, I
> like it's direction.  I find that there could be more options though.
>
> Recently I reported a bug about AC3 stereo not being passed through to
> the receiver.  I reported it because I thought it was a bug, but that's
> not to say I didn't like the behaviour.  I do prefer to have AC3 decoded
> by Myth because my receiver has some latency (and a click) between when
> it starts getting an AC3 track and when it starts decoding/playing it.
>

if you want AC3 to be decoded by myth, uncheck AC3 passthrough.
I understand what you are saying, and read below


> So it seems that what I would want to do is disable DD and DTS in my
> Myth config and enable LPCM, which I am guessing indicates to myth that
> I want it to do the AC3 decoding.  That's fine, except that the
> connection between my TV and my receiver is optical (and my FE->TV is
> HDMI) and so not capable of carrying 5.1 on LPCM (as far as I
> understand), but only 2.0.
>
> So what I would like to tell Myth is, that if the sound is AC3 and it's
> 2ch (or less), decode it and send it over LPCM, but if it's more than
> 2ch and it's DD or DTS then pass it through to the receiver for
> decoding.
>

I won't be adding such option. The idea is to simplify the setup, not make
it once again overcrowded with options 99% of the people won't use


> In order to achieve that it seems that I need an option box to tell Myth
> to prefer decoding AC3 itself when possible and I also need an input box
> to tell Myth how many channels it can use LPCM to send to the reciever.
>

This is already done internally.
Myth knows how many pcm channels the audio card support.

so if using spdif, it will send PCM for stereo only, anything multichannels
will be sent as DTS or AC3.

For hdmi, multichannels audio will be sent as LPCM where it can, or DTS/AC3
if passthrough has been selected.


>
> With regard to this latter option though, perhaps many people don't
> understand the abilities of HDMI vs. toslink so perhaps rather than a
> more technical option like specifying how many channels can be carried
> to the receiver a more simple/consumer-like option to specify whether
> your receiver is connected via optical cable or HDMI should be provided
> and from that, Myth determines how many channels it can send with LPCM.
>
> it already does that
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