Hi All,
I am new for this openWRT and i am interested in Audio on router.
I know there is GStreamer, FFMpeg, ALSA packages.
Just want to know the complete Audio Architecture on openWRT, e.g. how it communicate from user space to kernel space(it may be GStreamer+ffmepg), but i am not sure much about this.
Is there any tiny alsa? is there any HAL layer?Is it support H/W decoding, encoding?Is there any APP which is for PCM playback or non-pcm playback?

If possible, please share some document related to this?

Thanks
Ajay

Complex topic.

Most routers do not have native audio hardware.
This is because current target SoC not supporting it due to market reasons and/or engineering audio circuits with radio/RF circuits.

You have to search for some forum posts regarding "I2S" / audio codec
and ask there for documentation of the projects like airmusic nw11 or on projects which use OpenWrt firmware like carambola2 I2S on carambola2@8devices forum

"normal" Audio in OpenWrt is like:
- Linux Kernel provides "SoC" Audio (omap and afaik some sunxi or imx have these) or audio via attached USB Sound Card
- run alsa
- test with aplay
- mpd for playing all different sound formats
- use some app / program to control the mpd server running on router (console client, UI client, android app ...)

If you use Bluetooth devices you have to use pulseaudio since direct ALSA is not supported in newer versions - see http://wiki.openwrt.org/wiki/bluetooth.audio

In trunk, sunxi will get an audio driver with the 4.1 bump in the next few days. An i2s driver will likely also be made available, but that's experimental.