Mailing List Archive: MythTV: Users

Myth CVS + Alsa + S/PDIF

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mythtv at narkov

May 12, 2004, 9:55 PM

Post #1 of 13 (7718 views)
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Myth CVS + Alsa + S/PDIF

Hey guys,

I'm currently using myth from CVS and are having some problems with audio.

I'm attempting to output all audio via spdif to my receiver. The sound
card is a cheapie C-Media Electronics Inc CM8738 but works fine when
using mplayer. I assume that all the connections and hardware is working
fine given this.

I have tried ALSA 0.9.8 and 1.0.3. In Myth I have tried setting
ALSA:default, ALSA:spdif, ALSA:iec958 and also tried the OSS emulation
mode. Nothing works :( I can immediately drop out of myth and have it
working with mplayer.

Can anyone offer any advice?

Thanks,

Nick.

mediapc root # /usr/local/bin/mythbackend --version
0.15.20040505-1

mediapc root # uname -a
Linux mediapc 2.6.5-gentoo-r1 #3 Mon May 10 22:30:37 EST 2004 i686
Celeron (Coppermine) GenuineIntel GNU/Linux

mediapc root # lspci -vv
02:05.0 Multimedia audio controller: C-Media Electronics Inc CM8738 (rev 10)
Subsystem: C-Media Electronics Inc CMI8738/C3DX PCI Audio Device
Flags: stepping, medium devsel, IRQ 5
I/O ports at c800 [disabled] [size=256]
Capabilities: [c0] Power Management version 2

james at thearmstrongs

May 13, 2004, 6:26 AM

Post #2 of 13 (7609 views)
Permalink

Re: Myth CVS + Alsa + S/PDIF [In reply to]

Nick Adams wrote:

> Hey guys,
>
> I'm currently using myth from CVS and are having some problems with
> audio.
>
> I'm attempting to output all audio via spdif to my receiver. The sound
> card is a cheapie C-Media Electronics Inc CM8738 but works fine when
> using mplayer. I assume that all the connections and hardware is
> working fine given this.
>
> I have tried ALSA 0.9.8 and 1.0.3. In Myth I have tried setting
> ALSA:default, ALSA:spdif, ALSA:iec958 and also tried the OSS emulation
> mode. Nothing works :( I can immediately drop out of myth and have it
> working with mplayer.
>
> Can anyone offer any advice?
>
> Thanks,
>
> Nick.
>
>
> mediapc root # /usr/local/bin/mythbackend --version
> 0.15.20040505-1
>
> mediapc root # uname -a
> Linux mediapc 2.6.5-gentoo-r1 #3 Mon May 10 22:30:37 EST 2004 i686
> Celeron (Coppermine) GenuineIntel GNU/Linux
>
> mediapc root # lspci -vv
> 02:05.0 Multimedia audio controller: C-Media Electronics Inc CM8738
> (rev 10)
> Subsystem: C-Media Electronics Inc CMI8738/C3DX PCI Audio Device
> Flags: stepping, medium devsel, IRQ 5
> I/O ports at c800 [disabled] [size=256]
> Capabilities: [c0] Power Management version 2
>
>------------------------------------------------------------------------
>
>_______________________________________________
>mythtv-users mailing list
>mythtv-users [at] mythtv
>http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users
>
>
Same here. I don't know if anyone is looking at this yet. I am using the
Intel 810 sound chip. SPDIF works using mplayer ALSA:SPDIF, Myth does
not work.

- James

goincrazy at gmx

May 13, 2004, 9:44 AM

Post #3 of 13 (7579 views)
Permalink

Re: Myth CVS + Alsa + S/PDIF [In reply to]

James Armstrong schrieb:

> Same here. I don't know if anyone is looking at this yet. I am using
> the Intel 810 sound chip. SPDIF works using mplayer ALSA:SPDIF, Myth
> does not work.

I've a similar problem, see here:
http://www.gossamer-threads.com/lists/mythtv/users/67787
but only at TV functions, mythmusic and mythvideo (which uses mplayer
native with alsa)
are working flawless.

I didn't wrote this in my first mail to the list, but I'm using S/PDIF
too, maybee that's the problem...
I need to try regular analog output...

Steffen

john at sturgeonfamily

May 13, 2004, 4:03 PM

Post #4 of 13 (7624 views)
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Re: Myth CVS + Alsa + S/PDIF [In reply to]

james at thearmstrongs

May 13, 2004, 8:00 PM

Post #5 of 13 (7600 views)
Permalink

Re: Myth CVS + Alsa + S/PDIF [In reply to]

John Sturgeon wrote:

> Nick Adams wrote:
>
>> Hey guys,
>>
>> I'm currently using myth from CVS and are having some problems with
>> audio.
>>
>> I'm attempting to output all audio via spdif to my receiver. The
>> sound card is a cheapie C-Media Electronics Inc CM8738 but works fine
>> when using mplayer. I assume that all the connections and hardware is
>> working fine given this.
>>
>> I have tried ALSA 0.9.8 and 1.0.3. In Myth I have tried setting
>> ALSA:default, ALSA:spdif, ALSA:iec958 and also tried the OSS
>> emulation mode. Nothing works :( I can immediately drop out of myth
>> and have it working with mplayer.
>>
>> Can anyone offer any advice?
>>
>> Thanks,
>>
>> Nick.
>>
> Let me guess.. You get a floating point exception. Using OSS
> emulation is the only thing that works for me. Good luck.
>
> --
> John Sturgeon <><
> _______________________________________________
> mythtv-users mailing list
> mythtv-users [at] mythtv
> http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users

I am getting frustrated now. I have a big noisy backend in my living
room because it is the only thing I can watch recorded shows on. I built
a frontend using the MSI 865. I just got one of two things working
tonight that I needed before I can move the backend and start using the
frontend. I was tired of waiting for interlace with NVidia so I bought a
cheap SIS 315 card and had 1920x1080i working in about 10 minutes. Now
all I need is SPDIF to work. I can use mplayer and -ao alsa1x:spdif and
it works great. Myth still does not work with SPDIF. I just get audio
out the headset. My question is, is anyone really looking into this or
should I get another Audigy card that I know works with SPDIF. The
frontend is running the latest CVS and uses an Intel 8x0 chipset for
audio. The ALSA:spdif is no longer giving me floating point errors, it
just says, Unable to playback audio, Continue anyway?

- James

_______________________________________________
mythtv-users mailing list
mythtv-users [at] mythtv
http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users

john at sturgeonfamily

May 14, 2004, 2:40 PM

Post #6 of 13 (7562 views)
Permalink

Re: Myth CVS + Alsa + S/PDIF [In reply to]

James Armstrong wrote:

>
> I am getting frustrated now. I have a big noisy backend in my living
> room because it is the only thing I can watch recorded shows on. I
> built a frontend using the MSI 865. I just got one of two things
> working tonight that I needed before I can move the backend and start
> using the frontend. I was tired of waiting for interlace with NVidia
> so I bought a cheap SIS 315 card and had 1920x1080i working in about
> 10 minutes. Now all I need is SPDIF to work. I can use mplayer and -ao
> alsa1x:spdif and it works great. Myth still does not work with SPDIF.
> I just get audio out the headset. My question is, is anyone really
> looking into this or should I get another Audigy card that I know
> works with SPDIF. The frontend is running the latest CVS and uses an
> Intel 8x0 chipset for audio. The ALSA:spdif is no longer giving me
> floating point errors, it just says, Unable to playback audio,
> Continue anyway?
>
> - James
>
James,

When you talk about 1920x1080i, are you talking about your output
monitor output resolution, or high definition video playback?

--
John Sturgeon <><

james at thearmstrongs

May 16, 2004, 5:15 PM

Post #7 of 13 (7575 views)
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Re: Myth CVS + Alsa + S/PDIF [In reply to]

mythtv at narkov

May 16, 2004, 7:37 PM

Post #8 of 13 (7550 views)
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Re: Myth CVS + Alsa + S/PDIF [In reply to]

James Armstrong said:

> I finally got spdif working in mythtv on the Intel 810 chip using
> ALSA:spdif. [snip]

Can I ask how? I'm still without SPDIF audio.
_______________________________________________
mythtv-users mailing list
mythtv-users [at] mythtv
http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users

mythtv at narkov

May 17, 2004, 2:21 AM

Post #9 of 13 (7542 views)
Permalink

Re: Myth CVS + Alsa + S/PDIF [In reply to]

Nick Adams wrote:

> James Armstrong said:
>
>
>>I finally got spdif working in mythtv on the Intel 810 chip using
>>ALSA:spdif. [snip]
>
>
> Can I ask how? I'm still without SPDIF audio.

Turning off "Enable AC3 to SPDIF passthrough" makes/allows the audio to
work. This somehow doesn't seem like it's operating as it's designed to.
Yes/no?

steven.cruysberghs at pi

May 17, 2004, 5:42 AM

Post #10 of 13 (7549 views)
Permalink

Re: Myth CVS + Alsa + S/PDIF [In reply to]

>>
>> Can I ask how? I'm still without SPDIF audio.
>
> Turning off "Enable AC3 to SPDIF passthrough" makes/allows the audio to
> work. This somehow doesn't seem like it's operating as it's designed to.
> Yes/no?

It is operating as it is designed.
The ac3 passthrough is only usable if your tv broadcast have ac3 audio in
them. What you are doing is outputting stereo (2 channel) audio on the
spdif output
_______________________________________________
mythtv-users mailing list
mythtv-users [at] mythtv
http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users

james at thearmstrongs

May 17, 2004, 5:44 AM

Post #11 of 13 (7568 views)
Permalink

Re: Myth CVS + Alsa + S/PDIF [In reply to]

Nick Adams wrote:

> Nick Adams wrote:
>
>> James Armstrong said:
>>
>>
>>> I finally got spdif working in mythtv on the Intel 810 chip using
>>> ALSA:spdif. [snip]
>>
>>
>>
>> Can I ask how? I'm still without SPDIF audio.
>
>
> Turning off "Enable AC3 to SPDIF passthrough" makes/allows the audio
> to work. This somehow doesn't seem like it's operating as it's
> designed to. Yes/no?
>
>------------------------------------------------------------------------
>
>_______________________________________________
>mythtv-users mailing list
>mythtv-users [at] mythtv
>http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users
>
>

That is correct. Once I recompiled CVS with ALSA support I got it to
work only by turning off the AC3 passthrough off. I thought I read that
it was supposed to passthrough the AC3 signal if present. I figured that
if it was not present it would work as if it was not checked. With it
checked I get no audio at all. I had my frontend turned off this weekend
so I could not check to see if the AC3 option is also present on the
mythmusic page. I had mythtv working with spdif, just not mythmusic.

- James

paul_woodward at fastnet

May 17, 2004, 6:17 AM

Post #12 of 13 (7580 views)
Permalink

Re: Myth CVS + Alsa + S/PDIF [In reply to]

would it be possible to make this option fall-back if there is no AC3 audio for
a particular channel?

Quoting Steven Cruysberghs <steven.cruysberghs [at] pi>:

>
> >>
> >> Can I ask how? I'm still without SPDIF audio.
> >
> > Turning off "Enable AC3 to SPDIF passthrough" makes/allows the audio to
> > work. This somehow doesn't seem like it's operating as it's designed to.
> > Yes/no?
>
> It is operating as it is designed.
> The ac3 passthrough is only usable if your tv broadcast have ac3 audio in
> them. What you are doing is outputting stereo (2 channel) audio on the
> spdif output
> _______________________________________________
> mythtv-users mailing list
> mythtv-users [at] mythtv
> http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users
>

mythtv at narkov

May 17, 2004, 6:12 PM

Post #13 of 13 (7569 views)
Permalink

Re: Myth CVS + Alsa + S/PDIF [In reply to]

Steven Cruysberghs wrote:

>>> Can I ask how? I'm still without SPDIF audio.
>>
>> Turning off "Enable AC3 to SPDIF passthrough" makes/allows the
>> audio to work. This somehow doesn't seem like it's operating as
>> it's designed to. Yes/no?
>
>
> It is operating as it is designed. The ac3 passthrough is only usable
> if your tv broadcast have ac3 audio in them. What you are doing is
> outputting stereo (2 channel) audio on the spdif output
> _______________________________________________ mythtv-users mailing
> list mythtv-users [at] mythtv
> http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users
>

No it's not. The description presented when you highlight the option states:

"Enables sending AC3 directly to your sound card's SPDIF output, ***on
sources which contain AC3 soundtracks*** (usually digital TV). Requires
that the audio output device be set to something suitable".

The asterisks were added for emphasis. As you correctly stated, this
analog stereo source doesn't and couldn't contain an AC3 soundtrack so
according to that definition this option should have no effect.

So either that blurb of text needs to be updated or the behavior of the
option needs to be changed. I think the latter one would be preferred.

Thanks,

Nick Adams.

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