[mythtv-users] .24 Audio results: mixed

Jean-Yves Avenard jyavenard at gmail.com
Mon Jun 28 05:52:58 UTC 2010


Hi

On 28 June 2010 15:35, Douglas Peale <Douglas_Peale at comcast.net> wrote:
> If I set up Pulse Audio to use analog 7.1, is there a difference between using "ALSA:pulse" and
> "ALSA:surround71:CARD=Intel,DEV=0"? Both seem to work, and I'm getting sound out of all 7 speakers regardless of which one I choose.
> If I understand things correctly, "ALSA:pulse" would mix system sounds with TV sounds if selected, and
> "ALSA:surround71:CARD=Intel,DEV=0" would give me TV sound at the expense of system sounds. But I've misunderstood this so many
> times, I don't trust my thinking.

If you select ALSA:pulse it goes via pulseaudio

If you select ALSA:surround71, then the pulse audio server will be
suspended and only myth will be able to output sound during the time
it's active

As ALSA:pulse go through the pulseaudio server, all output will be
resambled to 44.1kHz, and down to 16 bits audio.

so if you don't care about having other sounds working while using
mythfrontend, I suggest you use ALSA:surround71 (or surround51, 50
etc... which interestingly, all reports 8 channels.. seems to just be
an alias to the same device, at least on my machine)


>
> Selecting "ALSA:iec958:CARD=Intel,DEV=0" changes "Audio Processing Capabilities" to a greyed check box for "LPCM" with that
> checkbox checked. Speaker configuration is stereo only, no other options. I don't see how to enable digital pass through on
> this. Is that because my Pulse setup outside of mythTV is now analog 7.1?

That's interesting..
Don't you see AC3 and DTS checkbox ?

Could be a bug.

>
> manually entering "ALSA:default" ungreys the analog or LPCM checkbox, and I can select between stereo, 5.1 and 7.1 when it is
> checked, or stereo only when unchecked. The options for digital pass through are still missing though.

if you type a custom device, all safeguards are removed, until you
press the "Scan" button which will then check that device
capabilities.
You'll then get a message if it's working or not

>
> I don't plan to switch back to digital pass through permanently, but I am trying to test all of these settings for you. I have
> left the SPDIF cable in parallel with the analog cables so I can test it.
>
> Under "Advanced audio configuration", the check boxes don't quite line up.
>
> the comment for "Separate digital output device" I'm not sure I understand. It says: "Use a distinct digital output device from
> the default". Does this mean "explicitly specify the digital output device, ignoring what the default specifies"? (I know that
> sentence is worded awkwardly, don't use my wording).

This is a deprecated option, if it was just me, I would have removed
it... but just in case , I left it.

If you're trying to send digital passthrough, it will use this
specified device instead of the currently selected in the default
device.


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