Configuration (. ASOUNDRC profile) that uses the ALSA plug-in to play 5.1-channel audio over a 2-channel stereo card

Just contact Alsa, I learned no one's words really very laborious. A lot of information on the internet did not have this explanation, finally see the official plug-in configuration document according to the personal understanding of the written experience:

(1) First look at the route plugin description:

This plugin can convert channels and change the volume. The configuration instructions are as follows:
Pcm.name {Type route # route & Volume Conversion PCM slave STR # slave name# orslave {# slave definition pcm STR # slave PCM name# orPCM {} # Slave PCM definition [format STR] # Slave format [channels INT] # Slav E channels} ttable {# Transfer table (bi-dimensional compound of cchannels * schannels numb ERs) Cchannel {SCHANNEL REAL # route value (0.0-1.0)}}}

(2) Take a look at the configuration example of 2-channel stereo conversion to mono:

pcm.makemono {    type route    slave.pcm "hw:0"    ttable {        0.0 1    # in-channel 0, out-channel 0, 100% volume        1.0 1    # in-channel 1, out-channel 0, 100% volume    }}

Pcm.downmix {

 type route SLAVE.PCM" hw:0.0 "ttable {0.0 1 # in-channel 0, Out-channel 0, 100% Volume 1.1 1 # in-channel 1, Out-channel 1, 100% volume  

 2.0 1  

 3.1 1  

 4.0 0.5  

 4.1 0.5  

 5.0 0.5  

        5.1 0.5   #意思是输入第5通道的数据传输给输出通道1，并且音量降低一半    }}

The following diagram can be used to map the above configuration:

Copyright NOTICE: This article for Bo Master original article, without Bo Master permission not reproduced.

Configuration (. ASOUNDRC profile) that uses the ALSA plug-in to play 5.1-channel audio over a 2-channel stereo card