Pulseaudio

我的 USB 音頻輸入通道最大輸出/剪輯約為 15%

  • January 24, 2022

我有一個 M-track 8 音頻設備（8 個 I/O）。它適用於播放。但是，麥克風（48 伏 XLR 麥克風）幾乎沒有發出任何聲音。錄製時，它們在任何應用程序中的音量上限為 15%。

  • 根據混頻器頻譜分析儀，它們工作得很好。
  • 如果我將 m-track 輸入重定向到模擬輸出並使用內置麥克風進行錄製，那麼它可以正常工作
  • 如果我在 macOS 或 Windows 中錄製，它可以正常工作。

所以問題出在 ALSA 或驅動程序的某個地方。這是一個普通的 USB 音頻類設備，因此驅動程序不太可能出現問題（在 Gentoo、Ubuntu 20.04 和 Ubuntu 18.04 live-usb 中重現）。

  • alsamixer顯示所有輸入為 100%
  • pavucontrol以 100% 顯示所有輸入
  • 我嘗試添加一些.asoundrc配置來強制 96kHz，但它什麼也沒做
  • 該問題與麥克風增強無關。信號超弱

混音器-c2：

Simple mixer control 'Mic',0
 Capabilities: cvolume cswitch
 Capture channels: Front Left - Front Right - Rear Left - Rear Right - Front Center - Woofer - Side Left - Side Right
 Limits: Capture 0 - 127
 Front Left: Capture 127 [100%] [0.00dB] [on]
 Front Right: Capture 127 [100%] [0.00dB] [on]
 Rear Left: Capture 127 [100%] [0.00dB] [on]
 Rear Right: Capture 127 [100%] [0.00dB] [on]
 Front Center: Capture 127 [100%] [0.00dB] [on]
 Woofer: Capture 127 [100%] [0.00dB] [on]
 Side Left: Capture 127 [100%] [0.00dB] [on]
 Side Right: Capture 127 [100%] [0.00dB] [on]
Simple mixer control 'Mic',1
 Capabilities: cvolume cvolume-joined cswitch cswitch-joined
 Capture channels: Mono
 Limits: Capture 0 - 127
 Mono: Capture 127 [100%] [0.00dB] [on]
Simple mixer control 'M-Audio M-Track Eight',0
 Capabilities: pvolume pswitch
 Playback channels: Front Left - Front Right - Rear Left - Rear Right - Front Center - Woofer - Side Left - Side Right
 Limits: Playback 0 - 127
 Mono:
 Front Left: Playback 121 [95%] [-6.00dB] [on]
 Front Right: Playback 121 [95%] [-6.00dB] [on]
 Rear Left: Playback 127 [100%] [0.00dB] [on]
 Rear Right: Playback 127 [100%] [0.00dB] [on]
 Front Center: Playback 127 [100%] [0.00dB] [on]
 Woofer: Playback 127 [100%] [0.00dB] [on]
 Side Left: Playback 127 [100%] [0.00dB] [on]
 Side Right: Playback 127 [100%] [0.00dB] [on]
Simple mixer control 'M-Audio M-Track Eight',1
 Capabilities: pvolume pvolume-joined pswitch pswitch-joined
 Playback channels: Mono
 Limits: Playback 0 - 127
 Mono: Playback 127 [100%] [0.00dB] [on]

lsusb -vv -d 0763:4003

Bus 001 Device 049: ID 0763:4003 M-Audio 
Couldn't open device, some information will be missing
Device Descriptor:
 bLength                18
 bDescriptorType         1
 bcdUSB               2.00
 bDeviceClass          239 Miscellaneous Device
 bDeviceSubClass         2 
 bDeviceProtocol         1 Interface Association
 bMaxPacketSize0        64
 idVendor           0x0763 M-Audio
 idProduct          0x4003 
 bcdDevice            1.05
 iManufacturer           1 
 iProduct                3 
 iSerial                 0 
 bNumConfigurations      2
 Configuration Descriptor:
   bLength                 9
   bDescriptorType         2
   wTotalLength       0x0148
   bNumInterfaces          4
   bConfigurationValue     1
   iConfiguration          0 
   bmAttributes         0x80
     (Bus Powered)
   MaxPower              500mA
   Interface Association:
     bLength                 8
     bDescriptorType        11
     bFirstInterface         0
     bInterfaceCount         3
     bFunctionClass          1 Audio
     bFunctionSubClass       0 
     bFunctionProtocol      32 
     iFunction               0 
   Interface Descriptor:
     bLength                 9
     bDescriptorType         4
     bInterfaceNumber        0
     bAlternateSetting       0
     bNumEndpoints           0
     bInterfaceClass         1 Audio
     bInterfaceSubClass      1 Control Device
     bInterfaceProtocol     32 
     iInterface              3 
     AudioControl Interface Descriptor:
       bLength                 9
       bDescriptorType        36
       bDescriptorSubtype      1 (HEADER)
       bcdADC               2.00
       bCategory               8
       wTotalLength       0x00a7
       bmControls           0x00
     AudioControl Interface Descriptor:
       bLength                 8
       bDescriptorType        36
       bDescriptorSubtype     10 (CLOCK_SOURCE)
       bClockID               41
       bmAttributes            3 Internal programmable clock 
       bmControls           0x07
         Clock Frequency Control (read/write)
         Clock Validity Control (read-only)
       bAssocTerminal          0
       iClockSource            9 
     AudioControl Interface Descriptor:
       bLength                 8
       bDescriptorType        36
       bDescriptorSubtype     11 (CLOCK_SELECTOR)
       bClockID               40
       bNrInPins               1
       baCSourceID(0)         41
       bmControls           0x03
         Clock Selector Control (read/write)
       iClockSelector          8 
     AudioControl Interface Descriptor:
       bLength                17
       bDescriptorType        36
       bDescriptorSubtype      2 (INPUT_TERMINAL)
       bTerminalID             2
       wTerminalType      0x0101 USB Streaming
       bAssocTerminal          0
       bCSourceID             40
       bNrChannels             8
       bmChannelConfig    0x00000000
       iChannelNames          19 
       bmControls         0x0000
       iTerminal               6 
     AudioControl Interface Descriptor:
       bLength                42
       bDescriptorType        36
       bDescriptorSubtype      6 (FEATURE_UNIT)
       bUnitID                10
       bSourceID               2
       bmaControls(0)     0x0000000f
         Mute Control (read/write)
         Volume Control (read/write)
       bmaControls(1)     0x0000000f
         Mute Control (read/write)
         Volume Control (read/write)
       bmaControls(2)     0x0000000f
         Mute Control (read/write)
         Volume Control (read/write)
       bmaControls(3)     0x0000000f
         Mute Control (read/write)
         Volume Control (read/write)
       bmaControls(4)     0x0000000f
         Mute Control (read/write)
         Volume Control (read/write)
       bmaControls(5)     0x0000000f
         Mute Control (read/write)
         Volume Control (read/write)
       bmaControls(6)     0x0000000f
         Mute Control (read/write)
         Volume Control (read/write)
       bmaControls(7)     0x0000000f
         Mute Control (read/write)
         Volume Control (read/write)
       bmaControls(8)     0x0000000f
         Mute Control (read/write)
         Volume Control (read/write)
       iFeature                0 
     AudioControl Interface Descriptor:
       bLength                12
       bDescriptorType        36
       bDescriptorSubtype      3 (OUTPUT_TERMINAL)
       bTerminalID            20
       wTerminalType      0x0301 Speaker
       bAssocTerminal          0
       bSourceID              10
       bCSourceID             40
       bmControls         0x0000
       iTerminal               0 
     AudioControl Interface Descriptor:
       bLength                17
       bDescriptorType        36
       bDescriptorSubtype      2 (INPUT_TERMINAL)
       bTerminalID             1
       wTerminalType      0x0201 Microphone
       bAssocTerminal          0
       bCSourceID             40
       bNrChannels             8
       bmChannelConfig    0x00000000
       iChannelNames          19 
       bmControls         0x0000
       iTerminal               0 
     AudioControl Interface Descriptor:
       bLength                42
       bDescriptorType        36
       bDescriptorSubtype      6 (FEATURE_UNIT)
       bUnitID                11
       bSourceID               1
       bmaControls(0)     0x0000000f
         Mute Control (read/write)
         Volume Control (read/write)
       bmaControls(1)     0x0000000f
         Mute Control (read/write)
         Volume Control (read/write)
       bmaControls(2)     0x0000000f
         Mute Control (read/write)
         Volume Control (read/write)
       bmaControls(3)     0x0000000f
         Mute Control (read/write)
         Volume Control (read/write)
       bmaControls(4)     0x0000000f
         Mute Control (read/write)
         Volume Control (read/write)
       bmaControls(5)     0x0000000f
         Mute Control (read/write)
         Volume Control (read/write)
       bmaControls(6)     0x0000000f
         Mute Control (read/write)
         Volume Control (read/write)
       bmaControls(7)     0x0000000f
         Mute Control (read/write)
         Volume Control (read/write)
       bmaControls(8)     0x0000000f
         Mute Control (read/write)
         Volume Control (read/write)
       iFeature                0 
     AudioControl Interface Descriptor:
       bLength                12
       bDescriptorType        36
       bDescriptorSubtype      3 (OUTPUT_TERMINAL)
       bTerminalID            22
       wTerminalType      0x0101 USB Streaming
       bAssocTerminal          0
       bSourceID              11
       bCSourceID             40
       bmControls         0x0000
       iTerminal               7 
   Interface Descriptor:
     bLength                 9
     bDescriptorType         4
     bInterfaceNumber        1
     bAlternateSetting       0
     bNumEndpoints           0
     bInterfaceClass         1 Audio
     bInterfaceSubClass      2 Streaming
     bInterfaceProtocol     32 
     iInterface              4 
   Interface Descriptor:
     bLength                 9
     bDescriptorType         4
     bInterfaceNumber        1
     bAlternateSetting       1
     bNumEndpoints           2
     bInterfaceClass         1 Audio
     bInterfaceSubClass      2 Streaming
     bInterfaceProtocol     32 
     iInterface              4 
     AudioStreaming Interface Descriptor:
       bLength                16
       bDescriptorType        36
       bDescriptorSubtype      1 (AS_GENERAL)
       bTerminalLink           2
       bmControls           0x00
       bFormatType             1
       bmFormats          0x00000001
         PCM
       bNrChannels             8
       bmChannelConfig    0x00000000
       iChannelNames          11 
     AudioStreaming Interface Descriptor:
       bLength                 6
       bDescriptorType        36
       bDescriptorSubtype      2 (FORMAT_TYPE)
       bFormatType             1 (FORMAT_TYPE_I)
       bSubslotSize            4
       bBitResolution         24
     Endpoint Descriptor:
       bLength                 7
       bDescriptorType         5
       bEndpointAddress     0x01  EP 1 OUT
       bmAttributes            5
         Transfer Type            Isochronous
         Synch Type               Asynchronous
         Usage Type               Data
       wMaxPacketSize     0x0400  1x 1024 bytes
       bInterval               1
       AudioStreaming Endpoint Descriptor:
         bLength                 8
         bDescriptorType        37
         bDescriptorSubtype      1 (EP_GENERAL)
         bmAttributes         0x00
         bmControls           0x00
         bLockDelayUnits         2 Decoded PCM samples
         wLockDelay         0x0008
     Endpoint Descriptor:
       bLength                 7
       bDescriptorType         5
       bEndpointAddress     0x81  EP 1 IN
       bmAttributes           17
         Transfer Type            Isochronous
         Synch Type               None
         Usage Type               Feedback
       wMaxPacketSize     0x0004  1x 4 bytes
       bInterval               4
   Interface Descriptor:
     bLength                 9
     bDescriptorType         4
     bInterfaceNumber        2
     bAlternateSetting       0
     bNumEndpoints           0
     bInterfaceClass         1 Audio
     bInterfaceSubClass      2 Streaming
     bInterfaceProtocol     32 
     iInterface              5 
   Interface Descriptor:
     bLength                 9
     bDescriptorType         4
     bInterfaceNumber        2
     bAlternateSetting       1
     bNumEndpoints           1
     bInterfaceClass         1 Audio
     bInterfaceSubClass      2 Streaming
     bInterfaceProtocol     32 
     iInterface              5 
     AudioStreaming Interface Descriptor:
       bLength                16
       bDescriptorType        36
       bDescriptorSubtype      1 (AS_GENERAL)
       bTerminalLink          22
       bmControls           0x00
       bFormatType             1
       bmFormats          0x00000001
         PCM
       bNrChannels             8
       bmChannelConfig    0x00000000
       iChannelNames          19 
     AudioStreaming Interface Descriptor:
       bLength                 6
       bDescriptorType        36
       bDescriptorSubtype      2 (FORMAT_TYPE)
       bFormatType             1 (FORMAT_TYPE_I)
       bSubslotSize            4
       bBitResolution         24
     Endpoint Descriptor:
       bLength                 7
       bDescriptorType         5
       bEndpointAddress     0x82  EP 2 IN
       bmAttributes            5
         Transfer Type            Isochronous
         Synch Type               Asynchronous
         Usage Type               Data
       wMaxPacketSize     0x0400  1x 1024 bytes
       bInterval               1
       AudioStreaming Endpoint Descriptor:
         bLength                 8
         bDescriptorType        37
         bDescriptorSubtype      1 (EP_GENERAL)
         bmAttributes         0x00
         bmControls           0x00
         bLockDelayUnits         2 Decoded PCM samples
         wLockDelay         0x0008
   Interface Descriptor:
     bLength                 9
     bDescriptorType         4
     bInterfaceNumber        3
     bAlternateSetting       0
     bNumEndpoints           0
     bInterfaceClass       254 Application Specific Interface
     bInterfaceSubClass      1 Device Firmware Update
     bInterfaceProtocol      1 
     iInterface             10 
     Device Firmware Upgrade Interface Descriptor:
       bLength                             9
       bDescriptorType                    33
       bmAttributes                        7
         Will Not Detach
         Manifestation Tolerant
         Upload Supported
         Download Supported
       wDetachTimeout                    250 milliseconds
       wTransferSize                      64 bytes
       bcdDFUVersion                   1.10
 Configuration Descriptor:
   bLength                 9
   bDescriptorType         2
   wTotalLength       0x0148
   bNumInterfaces          4
   bConfigurationValue     1
   iConfiguration          0 
   bmAttributes         0x80
     (Bus Powered)
   MaxPower              500mA
   Interface Association:
     bLength                 8
     bDescriptorType        11
     bFirstInterface         0
     bInterfaceCount         3
     bFunctionClass          1 Audio
     bFunctionSubClass       0 
     bFunctionProtocol      32 
     iFunction               0 
   Interface Descriptor:
     bLength                 9
     bDescriptorType         4
     bInterfaceNumber        0
     bAlternateSetting       0
     bNumEndpoints           0
     bInterfaceClass         1 Audio
     bInterfaceSubClass      1 Control Device
     bInterfaceProtocol     32 
     iInterface              3 
     AudioControl Interface Descriptor:
       bLength                 9
       bDescriptorType        36
       bDescriptorSubtype      1 (HEADER)
       bcdADC               2.00
       bCategory               8
       wTotalLength       0x00a7
       bmControls           0x00
     AudioControl Interface Descriptor:
       bLength                 8
       bDescriptorType        36
       bDescriptorSubtype     10 (CLOCK_SOURCE)
       bClockID               41
       bmAttributes            3 Internal programmable clock 
       bmControls           0x07
         Clock Frequency Control (read/write)
         Clock Validity Control (read-only)
       bAssocTerminal          0
       iClockSource            9 
     AudioControl Interface Descriptor:
       bLength                 8
       bDescriptorType        36
       bDescriptorSubtype     11 (CLOCK_SELECTOR)
       bClockID               40
       bNrInPins               1
       baCSourceID(0)         41
       bmControls           0x03
         Clock Selector Control (read/write)
       iClockSelector          8 
     AudioControl Interface Descriptor:
       bLength                17
       bDescriptorType        36
       bDescriptorSubtype      2 (INPUT_TERMINAL)
       bTerminalID             2
       wTerminalType      0x0101 USB Streaming
       bAssocTerminal          0
       bCSourceID             40
       bNrChannels             8
       bmChannelConfig    0x00000000
       iChannelNames          19 
       bmControls         0x0000
       iTerminal               6 
     AudioControl Interface Descriptor:
       bLength                42
       bDescriptorType        36
       bDescriptorSubtype      6 (FEATURE_UNIT)
       bUnitID                10
       bSourceID               2
       bmaControls(0)     0x0000000f
         Mute Control (read/write)
         Volume Control (read/write)
       bmaControls(1)     0x0000000f
         Mute Control (read/write)
         Volume Control (read/write)
       bmaControls(2)     0x0000000f
         Mute Control (read/write)
         Volume Control (read/write)
       bmaControls(3)     0x0000000f
         Mute Control (read/write)
         Volume Control (read/write)
       bmaControls(4)     0x0000000f
         Mute Control (read/write)
         Volume Control (read/write)
       bmaControls(5)     0x0000000f
         Mute Control (read/write)
         Volume Control (read/write)
       bmaControls(6)     0x0000000f
         Mute Control (read/write)
         Volume Control (read/write)
       bmaControls(7)     0x0000000f
         Mute Control (read/write)
         Volume Control (read/write)
       bmaControls(8)     0x0000000f
         Mute Control (read/write)
         Volume Control (read/write)
       iFeature                0 
     AudioControl Interface Descriptor:
       bLength                12
       bDescriptorType        36
       bDescriptorSubtype      3 (OUTPUT_TERMINAL)
       bTerminalID            20
       wTerminalType      0x0301 Speaker
       bAssocTerminal          0
       bSourceID              10
       bCSourceID             40
       bmControls         0x0000
       iTerminal               0 
     AudioControl Interface Descriptor:
       bLength                17
       bDescriptorType        36
       bDescriptorSubtype      2 (INPUT_TERMINAL)
       bTerminalID             1
       wTerminalType      0x0201 Microphone
       bAssocTerminal          0
       bCSourceID             40
       bNrChannels             8
       bmChannelConfig    0x00000000
       iChannelNames          19 
       bmControls         0x0000
       iTerminal               0 
     AudioControl Interface Descriptor:
       bLength                42
       bDescriptorType        36
       bDescriptorSubtype      6 (FEATURE_UNIT)
       bUnitID                11
       bSourceID               1
       bmaControls(0)     0x0000000f
         Mute Control (read/write)
         Volume Control (read/write)
       bmaControls(1)     0x0000000f
         Mute Control (read/write)
         Volume Control (read/write)
       bmaControls(2)     0x0000000f
         Mute Control (read/write)
         Volume Control (read/write)
       bmaControls(3)     0x0000000f
         Mute Control (read/write)
         Volume Control (read/write)
       bmaControls(4)     0x0000000f
         Mute Control (read/write)
         Volume Control (read/write)
       bmaControls(5)     0x0000000f
         Mute Control (read/write)
         Volume Control (read/write)
       bmaControls(6)     0x0000000f
         Mute Control (read/write)
         Volume Control (read/write)
       bmaControls(7)     0x0000000f
         Mute Control (read/write)
         Volume Control (read/write)
       bmaControls(8)     0x0000000f
         Mute Control (read/write)
         Volume Control (read/write)
       iFeature                0 
     AudioControl Interface Descriptor:
       bLength                12
       bDescriptorType        36
       bDescriptorSubtype      3 (OUTPUT_TERMINAL)
       bTerminalID            22
       wTerminalType      0x0101 USB Streaming
       bAssocTerminal          0
       bSourceID              11
       bCSourceID             40
       bmControls         0x0000
       iTerminal               7 
   Interface Descriptor:
     bLength                 9
     bDescriptorType         4
     bInterfaceNumber        1
     bAlternateSetting       0
     bNumEndpoints           0
     bInterfaceClass         1 Audio
     bInterfaceSubClass      2 Streaming
     bInterfaceProtocol     32 
     iInterface              4 
   Interface Descriptor:
     bLength                 9
     bDescriptorType         4
     bInterfaceNumber        1
     bAlternateSetting       1
     bNumEndpoints           2
     bInterfaceClass         1 Audio
     bInterfaceSubClass      2 Streaming
     bInterfaceProtocol     32 
     iInterface              4 
     AudioStreaming Interface Descriptor:
       bLength                16
       bDescriptorType        36
       bDescriptorSubtype      1 (AS_GENERAL)
       bTerminalLink           2
       bmControls           0x00
       bFormatType             1
       bmFormats          0x00000001
         PCM
       bNrChannels             8
       bmChannelConfig    0x00000000
       iChannelNames          11 
     AudioStreaming Interface Descriptor:
       bLength                 6
       bDescriptorType        36
       bDescriptorSubtype      2 (FORMAT_TYPE)
       bFormatType             1 (FORMAT_TYPE_I)
       bSubslotSize            4
       bBitResolution         24
     Endpoint Descriptor:
       bLength                 7
       bDescriptorType         5
       bEndpointAddress     0x01  EP 1 OUT
       bmAttributes            5
         Transfer Type            Isochronous
         Synch Type               Asynchronous
         Usage Type               Data
       wMaxPacketSize     0x0400  1x 1024 bytes
       bInterval               1
       AudioStreaming Endpoint Descriptor:
         bLength                 8
         bDescriptorType        37
         bDescriptorSubtype      1 (EP_GENERAL)
         bmAttributes         0x00
         bmControls           0x00
         bLockDelayUnits         2 Decoded PCM samples
         wLockDelay         0x0008
     Endpoint Descriptor:
       bLength                 7
       bDescriptorType         5
       bEndpointAddress     0x81  EP 1 IN
       bmAttributes           17
         Transfer Type            Isochronous
         Synch Type               None
         Usage Type               Feedback
       wMaxPacketSize     0x0004  1x 4 bytes
       bInterval               4
   Interface Descriptor:
     bLength                 9
     bDescriptorType         4
     bInterfaceNumber        2
     bAlternateSetting       0
     bNumEndpoints           0
     bInterfaceClass         1 Audio
     bInterfaceSubClass      2 Streaming
     bInterfaceProtocol     32 
     iInterface              5 
   Interface Descriptor:
     bLength                 9
     bDescriptorType         4
     bInterfaceNumber        2
     bAlternateSetting       1
     bNumEndpoints           1
     bInterfaceClass         1 Audio
     bInterfaceSubClass      2 Streaming
     bInterfaceProtocol     32 
     iInterface              5 
     AudioStreaming Interface Descriptor:
       bLength                16
       bDescriptorType        36
       bDescriptorSubtype      1 (AS_GENERAL)
       bTerminalLink          22
       bmControls           0x00
       bFormatType             1
       bmFormats          0x00000001
         PCM
       bNrChannels             8
       bmChannelConfig    0x00000000
       iChannelNames          19 
     AudioStreaming Interface Descriptor:
       bLength                 6
       bDescriptorType        36
       bDescriptorSubtype      2 (FORMAT_TYPE)
       bFormatType             1 (FORMAT_TYPE_I)
       bSubslotSize            4
       bBitResolution         24
     Endpoint Descriptor:
       bLength                 7
       bDescriptorType         5
       bEndpointAddress     0x82  EP 2 IN
       bmAttributes            5
         Transfer Type            Isochronous
         Synch Type               Asynchronous
         Usage Type               Data
       wMaxPacketSize     0x0400  1x 1024 bytes
       bInterval               1
       AudioStreaming Endpoint Descriptor:
         bLength                 8
         bDescriptorType        37
         bDescriptorSubtype      1 (EP_GENERAL)
         bmAttributes         0x00
         bmControls           0x00
         bLockDelayUnits         2 Decoded PCM samples
         wLockDelay         0x0008
   Interface Descriptor:
     bLength                 9
     bDescriptorType         4
     bInterfaceNumber        3
     bAlternateSetting       0
     bNumEndpoints           0
     bInterfaceClass       254 Application Specific Interface
     bInterfaceSubClass      1 Device Firmware Update
     bInterfaceProtocol      1 
     iInterface             10 
     Device Firmware Upgrade Interface Descriptor:
       bLength                             9
       bDescriptorType                    33
       bmAttributes                        7
         Will Not Detach
         Manifestation Tolerant
         Upload Supported
         Download Supported
       wDetachTimeout                    250 milliseconds
       wTransferSize                      64 bytes
       bcdDFUVersion                   1.10

pacmd list-sources inputs:

  index: 16
       name: <alsa_output.usb-M-Audio_M-Track_Eight-00.analog-surround-71.monitor>
       driver: <module-alsa-card.c>
       flags: DECIBEL_VOLUME LATENCY DYNAMIC_LATENCY
       state: RUNNING
       suspend cause: (none)
       priority: 1040
       volume: front-left: 65536 / 100% / 0.00 dB,   front-right: 65536 / 100% / 0.00 dB,   rear-left: 65536 / 100% / 0.00 dB,   rear-right: 65536 / 100% / 0.00 dB,   front-center: 65536 / 100% / 0.00 dB,   lfe: 65536 / 100% / 0.00 dB,   side-left: 65536 / 100% / 0.00 dB,   side-right: 65536 / 100% / 0.00 dB
               balance 0.00
       base volume: 65536 / 100% / 0.00 dB
       volume steps: 65537
       muted: no
       current latency: 0.00 ms
       max rewind: 11 KiB
       sample spec: s32le 8ch 44100Hz
       channel map: front-left,front-right,rear-left,rear-right,front-center,lfe,side-left,side-right
                    Surround 7.1
       used by: 5
       linked by: 5
       configured latency: 40.00 ms; range is 8.00 .. 743.04 ms
       monitor_of: 7
       card: 5 <alsa_card.usb-M-Audio_M-Track_Eight-00>
       module: 27
       properties:
               device.description = "Monitor of M-Track Eight Analog Surround 7.1"
               device.class = "monitor"
               alsa.card = "2"
               alsa.card_name = "M-Track Eight"
               alsa.long_card_name = "M-Audio M-Track Eight at usb-0000:00:14.0-5.4, high speed"
               alsa.driver_name = "snd_usb_audio"
               device.bus_path = "pci-0000:00:14.0-usb-0:5.4:1.0"
               sysfs.path = "/devices/pci0000:00/0000:00:14.0/usb1/1-5/1-5.4/1-5.4:1.0/sound/card2"
               udev.id = "usb-M-Audio_M-Track_Eight-00"
               device.bus = "usb"
               device.vendor.id = "0763"
               device.vendor.name = "M-Audio"
               device.product.id = "4003"
               device.product.name = "M-Track Eight"
               device.serial = "M-Audio_M-Track_Eight"
               device.string = "2"
               module-udev-detect.discovered = "1"
               device.icon_name = "audio-card-usb"

這是一段錄音：

parecord -r --format=s24le --file-format=wav ./foo.wav

file ./foo.wav

./foo.wav: RIFF (little-endian) data, WAVE audio, Microsoft PCM, 24 bit, stereo 44100 Hz

聲音來自麥克風並被夾在設備上（顯示了 vu-meter 紅色條）。

在此處輸入圖像描述

在此處輸入圖像描述

我沒有看到任何明顯的東西，但有兩個想法：

  1. USB 設備有兩種配置，但從顯示的有關它們的資訊來看，它們似乎是相同的。所以我不知道它們是乾什麼用的。您可以嘗試切換到另一個（使用usb_modeswitch，首先解除安裝核心模組），看看是否有任何改變
  2. 如果我正確讀取描述符，您將在 4 個字節中傳輸 24 位。如果通用 USB 音頻驅動程序選擇了錯誤的 3 個字節，您最終可能會得到一個最高有效字節為零，這會將級別限制為 12.5%（與您觀察到的 15% 匹配）。

parecord您可以通過以 24 位格式記錄（例如）到某個文件（WAV 或原始文件）並使用十六進制編輯器檢查它來驗證這一點。如果所有樣本的 MSB 為零，即使您在 Mac 或 Windows 上製作剪輯的音量，也很可能會出現這種情況。

此外，您可以使用wireshark擷取 USB 數據包，這樣您就可以比較它們是否在樣本中還有額外的第三個字節，而這些字節沒有進入記錄的數據中。

在這種情況下，這是驅動程序中的錯誤，因此請在 ALSA 核心列表上送出錯誤報告。

案例快速瀏覽：通常人們會購買 M-track 8 之類的設備來使用多個麥克風進行錄音，例如，樂隊成員只有一個或兩個麥克風（人聲 + 樂器）。在這種情況下，您只需從 Pulseaudio 獲得所有 8 個通道（禁用縮混），您的 DAW 將選擇您實際錄製的通道。

通常，您甚至會為此完全禁用 Pulseaudio，因為它只會增加延遲，然後直接轉到 ALSA，或者使用 Jack 而不是 Pulseaudio。

“我希望我的筆記型電腦可以播放到我的 7.1 環繞聲揚聲器或立體聲耳機中。然後，如果我進行電話會議，我只想讓人們聽到我的聲音。

好的，所以你有一個麥克風，這就是你在案例中的全部內容。您還想保留 Pulseaudio，因為您沒有延遲問題，並且您使用 8 個通道主要用於輸出。

所以看看module-remap-source並做類似的事情

load-module module-remap-source master=alsa_input.usb-MTRACK.analog-stereo channels=1 master_channel_map=front-left channel_map=mono

front-left您的麥克風所在的頻道在哪裡，並MTRACK替換為您的 M-Track 源的實際名稱（使用 eg pactl list short）。然後從新源記錄。

如果唯一的實際問題是 Pulseaudio 正在將所有 8 個通道下混為立體聲並降低電平，那麼您現在應該很好了。

如果還有其他問題，請按照評論中的說明，在沒有 Pulseaudio 並且僅使用 ALSA 的情況下測試所有 8 個通道，這樣我們可以排除 Pulseaudio 並查看問題是否出在 ALSA 驅動程序中。

引用自：https://unix.stackexchange.com/questions/687534

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