SLC TX documentation or example

[Anki]

The https://github.com/espressif/esp8266_mp3_decoder example is very useful for getting I2S out working and the I2S peripheral configuration for data in seems straight forward enough. However, the SLC TX configuration registers are a little more opaque. Could an example be provided for configuring the SLC for receiving data from I2S in?

In general, any documentation on the SLC / DMA system / registers would be very greatly appreciated.

[Peter]

I want also connect an I2S ADC. I have a PCM1803A sparkfun board. It works with a STM32F4 board in DMA mode with Interrupt at full and half buffer size. Any hints for the documentation of the ESP8266 config are welcome. But: can the ESP8266 send the data 48000 Samples/second*2 channels* 4 Bytes/Sample = 384000 Bytes/s ? I need only one channel. Conversion to RTP stream 1 channel 24 bit = 144000 Bytes/s + RTP Header should be possible.
Peter