[mythtv-users] Turtle Beach Audio Advantage Spdif help.

Allen Edwards allen.p.edwards at gmail.com
Thu Feb 5 04:23:48 UTC 2009


On Wed, Feb 4, 2009 at 4:30 PM, Gregory Hartman <ghartman17022 at gmail.com> wrote:
> Gregg wrote:
>> I have just installed Mythdora 10.21 as a frontend, and I am trying to
>> get The Turtle Beach Audioadvantage working with spdif.  When I select
>> ac3 pass through I get static.  I have looked at the groups, and
>> people suggest unmuting iec958 in alsamixer.  Unfortunately it does
>> not give me that option it only lists PCM.  Is there a way to enable
>> that option in alsa?  Should I create an .asoundrc file?  I heard
>> fedora didnt need it anymore.
>>
>> Here is what I get with aplay -l :
>> **** List of PLAYBACK Hardware Devices ****
>> card 0: default [USB Sound Device        ], device 0: USB Audio [USB Audio]
>>   Subdevices: 1/1
>>   Subdevice #0: subdevice #0
>>
>> I do not see digital in the list.  Shouldn't there be?
>>
>
> I'm fairly certain that this is a long-standing driver issue in ALSA.
>
> I have the same USB device and was unable to get AC3 passthrough to
> work. It looks like ALSA doesn't support AC3 playback on most USB
> devices because the devices don't follow the USB audio spec:
>
> "The USB driver currently doesn't support AC3 streams because we have
> never seen any device that would implement it according to the USB Audio
> specification."
>
> https://bugtrack.alsa-project.org/alsa-bug/view.php?id=1438
>
> https://bugtrack.alsa-project.org/alsa-bug/view.php?id=1615
>
> During my investigation this also seemed to hold on the Windows side:
> the vendor-specific driver was needed to allow AC3 passthrough.
>
> I was able to get DTS passthrough to work, but this isn't nearly as
> interesting because most of the ATSC shows are using AC3.
>
> Apparently there has been some progress with the M-Audio Audiophile USB:
>
> http://www.alsa-project.org/main/index.php/Changes_v1.0.14_v1.0.15_detail
>
> But at $160 it's quite an investment.
>
> Greg
>
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If you have an ASUS MB, there will be a spdif output on the board
somewhere.  You can buy an adapter or make one with 2 resistors and a
capacitor. I made one and it works.  Perhaps other MBs have this
feature as well.

Allen


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