[mythtv-users] Confused 5.1 Sound Mapping?

[HP-mini]

On Tue, 2015-08-04 at 19:29 -0400, Jim wrote:
> 
> On 08/04/2015 07:00 AM, Tim Draper wrote:
> >
> > ---- On Tue, 04 Aug 2015 02:31:32 +0100 Jim  wrote ----
> >>
> >> On 08/03/2015 11:28 AM, Jim wrote:
> >>>
> >>> On 08/03/2015 10:35 AM, Tim Draper wrote:
> >>>> ---- On Mon, 03 Aug 2015 14:37:27 +0100 Jim wrote ----
> >>>>> I am experiencing an odd mapping of the 5.1 sound channels. The
> >>>>> materials I've found on ALSA and Pulse have not led me to a remedy.
> >>>>> I've
> >>>>> tested all available configuration options in the Audio Setup, all with
> >>>>> the same result.
> >>>>>
> >>>>> The sound is not simply a front-back misalignment. When performing the
> >>>>> 5.1 speaker test built into Mythtv, or using speaker-test I find the
> >>>>> following:
> >>>>>
> >>>>> front left out of front right
> >>>>> front right out of rear left
> >>>>> rear left out of rear right
> >>>>> rear right out of front center
> >>>>> front center out of LFE
> >>>>> LFE out of front left
> >>>>>
> >>>>> Has anyone else experienced this and have any idea of how to fix it?
> >>>>>
> >>>> i'm going to start with the basics:
> >>>> - how are to connecting the FE to your speakers; AVR, amp, or direct
> >>>> speakers?
> >>>> - does 5.1 work correctly when you use another device via
> >>>> same/different connections?
> >>>> - i use pulseaudio for my setup and do get channel mis-configuring on
> >>>> first install before i've configured it. Have you ran 'pavucontrol'
> >>>> on the desktop and configured your output type correctly. iirc it's
> >>>> on the last/2nd-to-last tab where you get various options like
> >>>> analogue stereo, digital stereo, digital surround, spdif etc as the
> >>>> output method.
> >>>>
> >>>>
> >>>> my last install refused to work correctly. a fresh install &
> >>>> configure pavucontrol fixed it.
> >>>>
> >>> The computer is connected via HDMI to a Yamaha RX-V575 AV Receiver.
> >>> The receiver is directly driving all 5.1 speakers, and is connected
> >>> via HDMI to the TV. The TV speakers are off.
> >>>
> >>> A Blu-ray player is also connected via HDMI to the receiver. All 5.1
> >>> sound is normal when playing DVDs and Blu-ray discs via this player.
> >>>
> >>> I have run pavucontrol, selecting via the Configure tab the Digital
> >>> Surround 5.1. (HDMI) Output. The Output Devices tab shows the
> >>> expected information.
> >>>
> >>> I am glad to learn others have discovered and conquered this problem.
> >>> I am sad to hear that it may take a new install. Is there no way to
> >>> correct the mapping without a complete new install?
> >>>
> >>>
> >> I may have found a solution to the wrongly mapped 5.1 surround sound
> >> problem. There is a module, called module-remap-sink, available in the
> >> pulse audio module suite that supports remapping of all the speakers.
> >> I've not tested with all possible configurations but at least one
> >> configuration is working properly and now the sound is coming from the
> >> correct speakers. There may be more to address, but at least the wife is
> >> happy for now!
> >>
> >>
> > Thats good to know of that tool. Maybe one to try in the future when i next encounter an issue. Reinstalled an FE isnt much of an issue for me; i have it on USB stick, so that plus a 20minute dist-upgrade is quicker than spending hours finding a solution.
> >
> >
> >
> I should have asked for clarification early regarding your mention of 
> re-install. Glad to hear it is only the Mythtv FE and not the whole system!
> 
> _______________________________________________

A workaround for channel mapping bug with your h/w would be to use
bitstream/digital-pass-thru' for AC3 (& DTS etc) so you HT-amp/AVR does
the decoding. This is possible over SPDIF/HDMI/DVI/DP.
In mythtv audio setup you can tick which audio formats your HT amp
supports.

Only downside is no (easy) volume control in mythtv & no sharing (dmix)
audio output with other running programs.