Streaming from Banana Pi using gstreamer

Banana Pi M1+ is the upgraded version of the the trusty Banana Pi with a 40 pin header with some very useful interfaces for audio; namely the i2s-0 interface and spdif output pins routed into the  upper end pins.

I coupled my DAB module - which is a i2s master device - hence set Banana Pi as i2s slave (in fex file).  The connection can be tested with alsa record / play utils  ..

  arecord  -D hw:2 -f S16_LE -c 2  -r 48000 | aplay -D hw:3  -

where hw2: is the i2s input alsa device (the DAB input); hw:3 is the usb sound card Once the i2s input is proved working, its time to stream this input to my laptop at 192.168.99.130, udp port 5000. The gstreamer pipeline at Banana Pi end is:

   gst-launch-0.10 alsasrc  device=hw:2 ! 'audio/x-raw-int, endianness=(int)1234, signed=(boolean)true, width=(int)16, depth=(int)16, rate=(int)48000,channels=(int)2'! udpsink host=192.168.99.130 port=5000

and at my laptop:

 gst-launch udpsrc port=5000 ! 'audio/x-raw-int, endianness=(int)1234, signed=(boolean)true, width=(int)16, depth=(int)16, rate=(int)48000,channels=(int)2' ! pulsesink

and to play in vlc :

 vlc --demux=rawaud --rawaud-channels=2 --rawaud-samplerate=48000 udp://@:5000

The raw audio datarate for 48k sample rate, S16LE stereo is 1536 Kbits/s. This can easily be handled in a wifi connection, and I had no issues streaming raw over udp. The aggregate data rate will be around with 1.6Mbits/s . If this needs to be carried out in a leaner channel (i.e bluetooth) then opus encoder / decoder is an excellent choice.The opus encoded pipeline is:
 Server : (Banana Pi)

 gst-launch-0.10 alsasrc  device=hw:2 ! 'audio/x-raw-int, endianness=(int)1234, signed=(boolean)true, width=(int)16, depth=(int)16, rate=(int)48000,channels=(int)2' ! opusenc !  udpsink host=192.168.99.130 port=5000

client:

 gst-launch udpsrc port=5000 ! opusdec ! pulsesink

The processor usage for the raw pipeline is about 6~7% and for the opus encoded pipeline is ~25% - excellent !!