我有一个工作的PCM输出与良好的声音在树莓派计算模块( Linux )上使用的rpi dac。'aplay -l‘命令输出显示以下内容:
>> aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: sndrpirpidac [snd_rpi_rpi_dac], device 0: RPi-DAC HiFi pcm1794a-hifi-0 []
Subdevices: 1/1
Subdevice #0: subdevice #0
card 1: ALSA [bcm2835 ALSA], device 0: bcm2835 ALSA [bcm2835 ALSA]
Subdevices: 8/8
Subdevice #0: subdevice #0
Subdevice #1: subdevice #1
Subdevice #2: subdevice #2
Subdevice #3: subdevice #3
Subdevice #4: subdevice #4
Subdevice #5: subdevice #5
Subdevice #6: subdevice #6
Subdevice #7: subdevice #7
card 1: ALSA [bcm2835 ALSA], device 1: bcm2835 ALSA [bcm2835 IEC958/HDMI]
Subdevices: 1/1
Subdevice #0: subdevice #0
要让音频正常工作,我必须更改我的/etc/asound.conf文件,使其如下所示:
pcm.mmap0 {
type mmap_emul
slave {
pcm "hw:0,0"
}
}
pcm.!default {
type plug
slave {
pcm mmap0
}
}
当我播放.wav文件时,输出听起来很棒,但它有点安静,而且alsamixer不允许使用这个驱动程序控制音频音量。
我想得到更多的音量,所以我研究了Ladspa项目的软件放大器插件。下面的示例代码在normal Pi上增大3.5 mm插孔的音量:
pcm.radio {
type plug
slave.pcm "ladspa"
hint {
show on
description "in -> equal -> declip -> compressor -> limiter -> dmix -> out"
}
}
# LADSPA plugins:
# "listplugins" to see the list of installed plugins
# "analyseplugin <filename>" to see plugin controls
# Use "ardour2" to experiment with plugin settings
pcm.ladspa {
type ladspa
slave.pcm "plughw:0,0"
path "/usr/lib/ladspa"
plugins {
0 {
# Limiter
label amp
input {
controls [ 10 ]
}
}
}
}
我一直在阅读这里的文档:http://alsa.opensrc.org/Asoundrc,但我正在努力理解如何结合2-我想要的是MMAP仿真和放大。我如何才能做到这一点呢?谢谢。
发布于 2015-11-25 19:57:02
请尝试下一步设置,它可以在我的x86 linux下运行:
pcm.mmap0 {
type mmap_emul
slave {
pcm "hw:0,0"
# pcm ladspa
}
}
pcm.ladspa {
type ladspa
#slave.pcm "plughw:0,0"
slave.pcm mmap0
path "/usr/lib/ladspa"
plugins {
0 {
# Limiter
label amp
input {
controls [ 100 ]
}
}
}
}
pcm.!default{
type plug
slave {
pcm mmap0
#pcm ladspa
}
}
https://stackoverflow.com/questions/32507302
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