[mythtv] OT - Keeping HDMI audio link open

Kingsley Turner krt at krt.com.au
Fri Jun 24 00:11:01 UTC 2016

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.

     Run this in a terminal (or in /etc/rc.local, or ~/.gnomerc, or however 
you like):
     aplay -c2 -r48000 -fS16_LE < /dev/zero &



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