ALaw/uLaw sample formats
------------------------

This driver does not support the ALaw/uLaw sample formats.
ALaw is the default mode when opening a sound device
using OSS/Free. The reason for the lack of support is
that the hardware does not support these formats, and adding
conversion routines to the kernel would lead to very ugly
code in the presence of the mmap interface to the driver.
And since xquake uses mmap, mmap is considered important :-)
and no sane application uses ALaw/uLaw these days anyway.
In short, playing a Sun .au file as follows:

cat my_file.au > /dev/dsp

does not work. Instead, you may use the play script from
Chris Bagwell's sox-12.14 package (available from the URL
below) to play many different audio file formats.
The script automatically determines the audio format
and does do audio conversions if necessary.
http://home.sprynet.com/sprynet/cbagwell/projects.html


Blocking vs. nonblocking IO
---------------------------

Unlike OSS/Free this driver honours the O_NONBLOCK file flag
not only during open, but also during read and write.
This is an effort to make the sound driver interface more
regular. Timidity has problems with this; a patch
is available from http://www.ife.ee.ethz.ch/~sailer/linux/pciaudio.html.
(Timidity patched will also run on OSS/Free).


MIDI UART
---------

The driver supports a simple MIDI UART interface, with
no ioctl's supported.


MIDI synthesizer
----------------

The card both has an OPL compatible FM synthesizer but no
wavetable synthesizer.

I haven't managed so far to get the OPL synth running.


S/PDIF interface
----------------

Because the DAC or ADC must use 44K or 48K to process digital signal
from/to S/PDIF, playback to S/PDIF-out is activated when playing in
44k/48k frequency and SPDIF-loop not enabled.

Some CD-ROM need the SPDIF-in inverse set to work properly.


4 channels & 4 speakers
-----------------------

The 4 speakers for CMI8738 will behave depending on how do you use.
For general wave/MP3 player, you can hear sound from rear speakers
together with the front ones. This is like you use a Y-patch cable
but the 4 speakers mode will sent louder signal to rear speakers
because they are more far away from user than the front ones in
desktop application.


Support from C-Media
--------------------

Comment and bug report can be submitted at http://www.cmedia.com.tw
New version, update will bee published at
http://members.home.net/puresoft/cmedia.html first, then
http://www.cmedia.com.tw

Charles Tien
cltien@cmedia.com.tw
