audio pain

[Matthew S. Sacks]

bscott at ntisys.com wrote:

>On Wed, 14 Aug 2002, at 4:06pm, Matthew S. Sacks wrote:
>
>>The lspci command identifies the Multimedia audio controller as an Intel
>>Corp. 82801BA/BAM AC'97 (rev 05) (This may make sense if ADI chip has been
>>integrated onto a motherboard made by Intel....)
>>
>
>  FYI:  AC'97 = Audio Codec 1997.  It is an interface standard for cheap
>onboard sound.  Basically, it builds part of the sound into the core chipset
>of the motherboard, so that the actual sound chip(s) can be simpler/cheaper
>to produce.  So, on your PCI bus, you see the AC97 interface of the Intel
>chipset, which is then connected to the ADI chip.
>
>>When I try to play audio with the gnome CD player, the player seems to
>>think that it is playing - but I cannot hear anything.
>>
>
>  Do you actually get activity from the drive?  Does the light flash?
>
>  You see, there are two general methods of getting audio off a CD using a 
>CD-ROM drive.
>
>  The "traditional" way uses the CD-ROM drive like a glorified Discman(TM).  
>The laser reads the digital audio stream from the CD, and the drive's
>built-in digital-to-analog converter (DAC) turns it into analog audio.  A
>two-channel analog audio cable runs from the CD-ROM drive to the sound
>card's amplifier/mixer circuitry, and to the speakers.  The CPU and Linux are
>not involved (other than sending the "play" command).  In fact, if the
>CD-ROM has front panel buttons, you don't even need a working computer --
>just a power source.
>
>  The other, newer way is called Digital Audio Extraction, or DAE.  DAE
>reads the digital audio stream from the CD, but does not decode it in the
>CD-ROM drive.  Instead, it is sent to the host computer as data, like a
>software CD's files.  The host CPU is responsible for doing any processing,
>and has to send it out a sound card for you to hear music.
>
>  Each method has advantages.  Analog output from the CD-ROM leaves your
>CPU, memory, and system bus free to do other things.  DAE lets the computer
>add effects, analyze the audio stream for visualizations, and/or store the
>audio for later playback without the CD.
>
>  Many "CD player" programs can only handle the analog output method, and I
>am pretty sure that is what your computer is using.  There are two likely 
>causes of this problem.  One is that the analog audio cable from the CD-ROM 
>drive to the sound card was simply never installed.  If that is the case, 
>your best bet is likely to just switch to DAE -- more on that below.
>
>  However, the other possibility is equally likely, and easy to check: The
>CD audio channel on your sound card may be turned down (or off).  The sound
>card has an onboard mixer that can combine digital audio with analog
>sources, and each channel has its own volume control.  From the GNOME "foot"
>menu, do Programs -> Multimedia -> Audio Mixer, and check the "CD" slider.
>
>>Same thing happens with XMMS.  XMMS load files button does not see any
>>files on the CD.
>>
>
>  XMMS's standard "CD Audio Player" plug-in is kind of funky.  It "fakes"  
>having the CD mounted, as if the audio tracks were in the filesystem.  I
>never really liked it, and have seen it do weird things.  I always use
>instead the "AudioCD Reader" plug-in.  It does DAE, along with CDDB lookups,
>and generally behaves in a saner fashion.  You can get it from:
>
>	ftp://mud.stack.nl/pub/OuterSpace/willem/
>
I have downloaded several .gz files from this site.  gunzip will not 
unzip any of them.  Yes, I did -d.

?????



>
>
>  Yell if you need help installing it; it is pretty easy, but if you've
>never built something from source before, it can appear daunting.
>
>>The sndconfig utility identifies the audio card as the Intel 82801, and
>>plays an audio clip of a man saying that he pronounces Unix as Linux.
>>
>
>  "Heeelo, my name is Lee-nus Torvahlds, and I pronounce Lee-nooks like
>Lee-nooks."  ;-)
>
>>The quality of that sound clip is very poor, but it is coming out of the
>>speakers.
>>
>
>  The clip is, while "classic", not of terribly good quality.  See if you
>can track down a sound sample you "know" is good (an MP3 or WAV file would
>work), and play that.
>