Re: Re: [PATCH] Add support for Acer TravelMate and similar laptops

[Lee Revell <rlrevell@joe-job.com>]

On Wed, 2006-03-01 at 09:52 +1030, Jonathan Woithe wrote:
> The "CD" input on the ALC260 is an analog input.  It expects the CD drive to
> do all the audio decoding and present an ordinary stereo signal to this pin. 
> If when playing a CD and enabling the "CD" control you get no audio that
> strongly suggests that there is no audio signal running to that pin.
> However, if there is no analog connection to the ALC260 one does wonder
> precisely how these systems are expected to play CDs.  The only option 
> left would be for software to read the raw CD bitstream (which isn't a straight
> audio bitstream), decode it and then send the resulting audio bitstream to
> the DAC.  Given that CD drives are more than capable of doing all this it would
> surprise me if this were the case.
> 
> One thing worth checking though - have you tested *all* ALC260 inputs with
> the CD playing?  Maybe Acer connect the CD audio to some other ALC260 pin. 

I would not be surprised if some vendors were leaving out the DAC from
their CD drives, and expect you to play audio CDs in digital mode.  I
believe this is how Windows Media Player works by default (it also
allows it to generate visual effects from the CD audio).  You might just
have to use a player that implements CD playback this way.

Lee



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