A52 OUTPUT PLUGIN
=================

This plugin converts S16 linear format to A52 compressed stream and
send to an SPDIF output.  It requires libavcodec for encoding the
audio stream.

A PCM using this plugin can be defined like below:

	pcm.myout {
		type a52
	}

In addition, the following options are available:

- The "card" option specifies the card ID or number of the SPDIF.
  The output PCM becomes "iec958:{CARD=$CARD}" with extra AESx
  settings.  When omitted, the default card is used.

- The "slavepcm" option specifies a string of the slave PCM
  explicitly.  This is useful if a device has no proper SPDIF
  configuration (e.g. usb-audio), or if you want to pass your own PCM
  definition.  This option is exclusive with "card" option.

- The "rate" option specifies the input/output sample rate in HZ.
  The accepted rate is either 44100 or 48000.
  When omitted, 48000 is used.

- The "channels" option specifies the number of _input_ channels.
  It must be either 2, 4 or 6.  The default value is 6.

- The "bitrate" option specifies the bit-rate of the compressed
  stream in kbps.  Too small or too big value may not be accepted by
  the encoder.  When omitted, 448 is used.

- The "format" option specifies the output format type.  It's either
  S16_LE or S16_BE.  As default, S16_LE is used.

An example using the secondary card, 44.1kHz, 4 channels, output
bitrate 256kbps and output format S16_BE looks like below: 

	pcm.myout {
		type a52
		card 1
		rate 44100
		channels 4
		bitrate 256
		format S16_BE
	}

For using slavepcm option,

	pcm.mypcm {
		card 1
		device 2
	}

	pcm.myout {
		type a52
		slavepcm "mypcm"
	}


The plugin reads always S16 format (i.e. native-endian) as input, so
you'd need plug layer appropriately to covert it.