ALSA driver for raop_play

Compile and Install:

        Get source code and extract tar.gz file.
        (the deb package doesn't include this module.)
        
        cd drivers
        make
        (become the root user)
        make install

How to play:

• Become the root user and run "driver_start" script, which is in "drivers" directory.
• Run "aexcl_play" and play "alsadev.pls", which is in "raop_play" direcotry.
• Then play any audio player which can be configured to use a user defined alsa device. Most likely your alsa_raoppcm becomes the second sound device which is hw:1,0

        e.g.
          * mplayer: mplayer -ao alsa:device=hw=1.0 song_file
          * mpg321:  mpg321 -o alsa09 -a hw:1,0 song_file

        If you don't want to use the gui, you can run raop_play from the command line, but
        you need to know the ip address of your AEX.
          * raop_play your_aex_ip /tmp/pcmout

        To use as KDE sound system, go to 'Control Center' - 'Sound System' - 'Hardware',
        check 'Override device loaction' and set the device name like 'hw:1,0'

Known issues:

• Alsa controller is not yet written, so all controls from audio player software have a big latency.
• Sometimes, a little noise at the top of play.
• Under bad network conditions, song play becomes somehow strange.
• need a small systray-kind of gui.
• kernel 2.4 is not yet supported.
• the final period of song data may not be transfered.

Short description about the program:

        alsa_raoppcm is a simple alsa pcm driver, which gets sound data from the upper alsa
        layer and feed the data to a character device instead of audio hardware.

        The character device is also created in the same driver and which has dynamically
        assigned major node. It can be seen in /proc/devices once the module is successfully
        installed.

        raop_play reads pcm data from that character device.  When there is no data from the
        device, raop_play keeps sending a small silent data and tries not to be disconnected.

12/16/2005
Shiro Ninomiya <shiron_AT_snino_DOT_com>