[mythtv-users] "Woodchuck" sound on TV playback

Michael T. Dean mtdean at thirdcontact.com
Sun Aug 17 19:50:09 UTC 2008


On 08/17/2008 03:01 PM, John Welch wrote:
> Yes!  Thank you, thank you, thank you!  My problem is solved.  The
> keys were the changes in steps 3 & 4.
>
> Maybe this is explained elsewhere, but I couldn't find it, so can
> anyone tell me what "ALSA:iec958:(AESO 0x02)" means, particularly the
> "AES 0x02" part?

Says to set the IEC958 status bit for data type to non-audio (i.e. 
encoded audio formats, like AC-3 or DTS).

>   Also, can anyone tell me how to pass this along to
> mplayer?

Well, you can do it like you're doing with Myth, by specifying a 
partially correct***, but completely unintelligible, /ALSA/ 
configuration string within the settings for that one application 
(something like:  mplayer -ao "alsa:device="iec958={CARD 0 AES0 0x02}" 
-ac hwac3, /path/to/file), or you can set up your ALSA configuration 
correctly and give the configuration a useful and easy to remember name, 
like "passthrough" that can be used for any and all applications (i.e. 
Myth "Passthrough output device" would be "passthrough", mplayer could 
be started with mplayer -ao alsa:device=passthrough -ac hwac3, 
/path/to/file).

Oh, but wait, I must not know what I'm talking about because the wiki 
says that you don't need an ALSA configuration file...

Mike "doing it wrong because he puts ALSA configuration in the, er, ALSA 
configuration file" Dean

*** "partially correct" meaning that you really should specify all the 
IEC958 status bits because someone may have left them set for some other 
type of audio...  For Myth's HDTV recordings, AES0 0x06, AES1 0x82, AES2 
0x00, AES3=0x02 is probably what you'd want.


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