如何創建輸出到 HDMI 和耳機插孔的 ALSA 虛擬設備？

我可以告訴我的程序輸出到 HDMI或耳機插孔就好了，但是有沒有辦法在 asound.conf 中創建一個同時輸出到兩者的虛擬設備？

這個配置非常接近工作，但它會在耳機插孔上產生一種脈衝噪音。

pcm.internal {
 type hw
 card 1
 device 0
}

pcm.hdmi_hw {
 type hw
 card 0
 device 7
}

pcm.hdmi_complete {
 type softvol
 slave.pcm hdmi_hw
 control.name hdmi_volume
 control.card 1
}

pcm.sirmix {
   type plug
   slave.pcm {
       type multi
       slaves {
           a { channels 2 pcm "internal" }
           b { channels 2 pcm "hdmi_complete" }
       }
       bindings {
           0 { slave a channel 0 }
           1 { slave a channel 1 }
           2 { slave b channel 0 }
           3 { slave b channel 1 }
       }

   }
   ttable [
       [ 1 0 1 0 ]
       [ 0 1 0 1 ]
   ]
}

gst-launch-1.0 audiotestsrc ！音頻轉換！alsasink device=“sirmix”

所以顯然上面的設置和管道基本上是好的，如果你去 ALSA 論壇，他們會推薦類似上面的東西，但是rate你的輸出匹配是必須另外考慮的。

pcm.internal {
 type hw
 card 1
 device 0
 rate 48000
}

pcm.hdmi_hw {
 type hw
 card 0
 device 7
 rate 48000
}

我的最終配置文件如下：

pcm.m_headphone_mixed {
type dmix
ipc_key 595900
ipc_perm 0666
slave {
 pcm "hw:1,0" 
 rate 48000
 period_time 0
 period_size 1024
 buffer_size 4096
 format S16_LE
}
bindings {
 0 0
 1 1  
}
}

pcm.m_headphone_rate_adjusted {
type rate
slave {
 pcm "m_headphone_mixed"
 rate 48000
}
}

pcm.m_headphone {
type softvol
slave.pcm m_headphone_rate_adjusted
control.name m_headphone_volume
control.card 1
}

pcm.m_hdmi_mixed {
type dmix
ipc_key 595901
ipc_perm 0666
slave {
 pcm "hw:0,7"
 rate 48000
 period_time 0
 period_size 1024
 buffer_size 4096
 format S16_LE
 channels 2
}
bindings {
 0 0 # channel 0 -> channel 0 
 1 1
}
}

pcm.m_hdmi {
type softvol
slave.pcm "m_hdmi_mixed"
control.name m_hdmi_volume
control.card 1 
}

pcm.m_all_base {
type plug

slave.pcm {
  type multi
  slaves {
      a { channels 2 pcm "m_hdmi" }
      b { channels 2 pcm "m_headphone" }
  }
  bindings [
      { slave a channel 0 }
      { slave a channel 1 }
      { slave b channel 0 }
      { slave b channel 1 }
  ]
} 
}

pcm.m_all_routed {
type route
slave.pcm "m_all_base"
slave.channels 4

ttable [
 [ 1 0 1 0 ] # route left to channels 0,2
 [ 0 1 0 1 ] # route right to channels 1,3
]
}

pcm.m_all {
type softvol;
control.name m_all_volume;
control.card 1
slave.pcm "m_all_routed"
}

pcm.!default "m_all"

這樣做是為了讓標準戴爾台式 PC 同時輸出到耳機插孔和 DisplayPort。

引用自：https://unix.stackexchange.com/questions/231344