[mythtv-users] SPDIF Passthrough stopped working again

[Ole Nissen]

One more thing..

I notice that if I see a movie which has 2 ch normal and 2ch AC3 then
changing to the AC3 stream doesn't route the stream through the passthrough
device. This makes perfect sense, but I still think it would be a nice
behavior. I think a lot of people like me has a AC3/DTS amplifier without
HDMI input, which would like this feature.

Anyway thanks for all your help.

Ole

2011/1/9 Ole Nissen <mail at olenissen.com>

> Hi again
>
> Well I found the right combination:
>
> ----------
>
> Sound outputdevice: ALSA: hdmi:CARD=NVidia,DEV=0
>
> Digital Audio Capabilities:
> Dolby digital + DTS
>
> Speaker configuration: 5.1
>
> Don't upscale to 5.1 surround (They are greyed out)
>
> Advanced sound configuration checked.
>
> Resample not checked
> Force sounddevice to 48kHz output no checked
> Seperate digital output device: ALSA:iec958:{ AES0 0x06}
>
> Stereo PCM checked.
>
> Internal sound control disabled
> -------------
>
> As you explained, when it is playing 2 ch it will be passed to HDMI, but if
> more channels chosen, then it will be passed to passthrough device..
> This was not how it was setup last it worked, but it seems its ok now.
>
> Thank you very much for your inputs.
>
> Ole
>
>
> 2011/1/9 Ole Nissen <mail at olenissen.com>
>
> Hi
>>
>> You sound so sure, so I believe that what your telling me is true..
>>
>> I think I have tried all possible combinations i think. This is how its
>> currently set, which ofcause doesn't work eighter:
>>
>>
>> Sound outputdevice: ALSA: hdmi:CARD=NVidia,DEV=0
>>
>> Digital Audio Capabilities:
>> Dolby digital + DTS
>>
>> Speaker configuration: Stereo
>> Don't upscale to 5.1 surround (They are greyed out)
>>
>> Advanced sound configuration checked.
>>
>> Resample not checked
>> Force sounddevice to 48kHz output no checked
>> Seperate digital output device: ALSA:iec958:{ AES0 0x06}
>>
>> Stereo PCM only NOT checked.
>>
>> Internal sound control disabled
>>
>> Still no passthrough. Which of these settings are false?
>>
>>
>> 2011/1/9 Jean-Yves Avenard <jyavenard at gmail.com>
>>
>>> Hi
>>>
>>>
>>> On 10 January 2011 00:57, Ole Nissen <mail at olenissen.com> wrote:
>>> > Hi again,
>>> >
>>> > After reading the posts you were referring to I'm beginning to get the
>>> > picture. But...
>>> >
>>> > The HDMI device which is my primary device supports up to 7.1 channels.
>>> The
>>> > overall Audio capability is set to AC3 and DTS.
>>> > The HDMI device is only my flatpanel TV which has only 2 speakers
>>> therefore
>>> > I set the speaker configuration to stereo.. This means that all audio
>>> > upscaling is disabled... If I have a passthough device which supports
>>> more
>>> > than stereo, the logic would be to choose this for audio if the primary
>>> > device cant handle it (This should be the case for me if i'm trying to
>>> play
>>> > more than 2 ch audio), instead of downscaling to stereo, but I guess
>>> that is
>>> > not the case.
>>>
>>> I explained in that other post what was going on ; you have configure
>>> myth in such way that it requires audio processing to be applied,
>>> forcing myth to decode the audio to be able to apply some processing.
>>> As soon as you do that, it's not passthrough anymore is it ?
>>> Passthrough means passthrough: the audio stream is passed as is, no
>>> processing involved.
>>>
>>> Remember, it's because of how you configured myth that processing has
>>> to be enabled. Disable the option that are most likely causing
>>> processing to be performed and the issue is gone.
>>> That is, don't check flags like 48k audio override, don't use software
>>> volume control, don't use audio upmixing, don't force resample etc..
>>>
>>> This override passthrough device is a settings that was never design
>>> to be used for cases like you are using now ; it's a side effect.
>>>
>>>
>>> >
>>> > How is it ever possible to use a passthrough device if you have a HDMI
>>> > device which natively accepts multichannels, if not the speaker
>>> > configuration is honored? If the speakerconfiguration is set to stereo,
>>> then
>>> > the multichannel audio iś converted to stereo before its send to the
>>> hdmi
>>> > device. If the speaker configuration is set to 5.1 then multichannel
>>> audio
>>> > is simply passed to the HDMI device.. Never to the passthrough device..
>>>
>>> That's why you have the "StereoPCM" flag for.
>>>
>>> Check that, and it will never try to ouput LPCM audio, instead will
>>> re-encode all audio to AC3
>>>
>>> You have checked 48k override, so if you try to play any file that
>>> aren't 48kHz ; it will have to resample : meaning decoding the audio.
>>>
>>> Is there any particular reasons you checked that flag? In 99.9% of the
>>> time there should be no reason whatsoever to check that flag . I only
>>> put it there to fix the problem of ONE person.
>>> He had an audio card for which if you fed it anything other than 48k
>>> would crash and will necessitate a reboot.
>>>
>>> >
>>> > How I need it to work, worked like a charm for a little more than a
>>> week
>>> > ago.
>>>
>>> you must have changed the audio configuration, simple as that
>>> _______________________________________________
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>>> mythtv-users at mythtv.org
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>>>
>>
>>
>
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