[mythtv] OT - Keeping HDMI audio link open

Kingsley Turner krt at krt.com.au
Fri Jun 24 00:46:15 UTC 2016

On 24/06/16 10:11, Kingsley Turner wrote:
> On 23/06/16 19:46, Mark Perkins wrote:
>>> -----Original Message-----
>>> From: mythtv-dev [mailto:mythtv-dev-bounces at mythtv.org] On Behalf Of
>>> John Veness
>>> Sent: Thursday, 23 June 2016 5:55 PM
>>> To:mythtv-dev at mythtv.org
>>> Subject: Re: [mythtv] OT - Keeping HDMI audio link open
>>> On 23/06/2016 05:11, Kingsley Turner wrote:
>>>> hi,
>>>> I have an annoyance with MythTV, it's not Myth, but my amplifier.
>>>> The amp goes to some quasi-sleep-state, and takes about 2-4 seconds
>>>> for audio to start.
>>>> That's fine if it's a movie (with studio-self-promotion at the
>>>> beginning), but for music clips etc, it's quite a PITA as you have to
>>>> rewind.
>>>> I was thinking about using the ALSA libs to write a little program
>>>> that continuously plays a silent clip to keep the line open. Maybe the
>>>> program would also look for DPMS events and stop when the screen-saver
>>>> comes on too.
>>>> Does this seem to be the correct way to go about alleviating this ?
>>>> thanks,
>>>> -kt
>>> You might want to look at my recent thread "HDMI keep alive, maybe via
>>> sending silent audio?"
>>> http://www.gossamer-threads.com/lists/mythtv/users/599838  where I had
>>> the same problem as you. I tried to fix it by periodically playing a
>> silent WAV
>>> file, which kept is alive, but then had the problem that starting playback
>> in
>>> MythTV would sometimes say that it couldn't play any audio. I didn't get
>> any
>>> further and gave up in the end, and wired up my devices differently.
>>> I think the best software solution would be something integrated into Myth
>>> itself, so that it would properly start/stop the playback of silent audio
>> when
>>> going into/out of menus, but I don't know how to do that.
>>> John
>>> --
>>> John Veness, MythTV user, UK, DVB-T
>>> _______________________________________________
>> John, in your testing did you try something like the solution presented here
>> -
>> https://www.tolaris.com/2011/07/03/solving-the-2-second-sound-delay-with-xbm
>> c-and-hdmi/
>> Kingsley, might work for your situation as well.
>> To be honest (full disclosure I have no real experience with this kind of
>> stuff so make of it what you will) playing silence has never really felt
>> 'right' to me. I find it hard to image that that is what the manufacturers
>> of the other devices (roku et al) are doing. I did a little googling about
>> power saving and modules going into suspended mode and found this link
>> http://askubuntu.com/questions/218444/sound-output-starts-delayed  which has
>> two proposed solutions regarding preventing audio modules from going into
>> sleep / power save modes.
> Thanks Mark,
> I have tried telling pulse audio to no longer suspend-on-idle, and this 
> did significantly alleviate the problem - sometimes saving a second or two.
> I've since removed PA completely from my mythbox.
> I'll try the suggestion on that first link, see if there's any joy.
> Ref: 
> https://www.tolaris.com/2011/07/03/solving-the-2-second-sound-delay-with-xbmc-and-hdmi/
>     Run this in a terminal (or in /etc/rc.local, or ~/.gnomerc, or however 
> you like):
>     aplay -c2 -r48000 -fS16_LE < /dev/zero &
> [/QUOTE]

Ok, so trying this for my system:
     aplay -D hw:CARD=NVidia,DEV=7 -c2 -r48000 -fS16_LE < /dev/zero

It caused MythTV to not be able to open the audio port.
I thought ALSA may have handled this automatically and simply mixed the 
audio, but it did not.

None of the intel driver lower-power mode things seemed to do anything.
But I don't even know if it uses the intel stuff on the motherboard at all - 
it all goes out through NVidia HDMI.
Does nVidia still use intel audio ?


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