Question

我正在编写一个新的Android Audio HAL，让我的应用程序将音频提供给其他应用程序，以允许我的掌上电脑远程麦克风输入到达Google应用程序。基本上是一条虚拟音频线。

它正在进行中。我可能会覆盖AUDIO_DEVICE_IN_BACK_MIC，但这是有建议的。

我怀疑如何确保Android使用此HAL进行输入。

我是否需要替换audio.primary.default.so，还是应该将其保留为audio.vcable.default.so？

更具体地说：如果我没有替换主要内容，Android将如何知道使用我的HAL而不是主要？

更新

我真的可以在这项工作中使用任何帮助。任何指针都有帮助。

我写过一个Audio HAL模块。我在audio_policy.conf中添加了以下（粗体项）：

全局：

global_configuration {
  attached_output_devices AUDIO_DEVICE_OUT_SPEAKER|**AUDIO_DEVICE_OUT_LINE**
  default_output_device AUDIO_DEVICE_OUT_SPEAKER
  attached_input_devices AUDIO_DEVICE_IN_BUILTIN_MIC|AUDIO_DEVICE_IN_BACK_MIC|AUDIO_DEVICE_IN_REMOTE_SUBMIX|**AUDIO_DEVICE_IN_LINE**
}

并在audio_hw_modules下

  vloop {
    inputs {
      vloop {
        sampling_rates 16000
        channel_masks AUDIO_CHANNEL_IN_MONO
        formats AUDIO_FORMAT_PCM_16_BIT
        devices AUDIO_DEVICE_IN_LINE
      }
    }
    outputs {
      vloop {
        sampling_rates 16000
        channel_masks AUDIO_CHANNEL_OUT_STEREO
        formats AUDIO_FORMAT_PCM_16_BIT
        devices AUDIO_DEVICE_OUT_LINE
        flags AUDIO_OUTPUT_FLAG_DIRECT
      }
    }
  }

我还在AudioFlinger.cpp中添加了以下（粗体）

static const char * const audio_interfaces[] = {
    AUDIO_HARDWARE_MODULE_ID_PRIMARY,
    AUDIO_HARDWARE_MODULE_ID_A2DP,
    AUDIO_HARDWARE_MODULE_ID_USB,
    **AUDIO_HARDWARE_MODULE_ID_VLOOP**
};

我可以看到在启动过程中，我的HAL被加载了，我得到了这些日志：

10-06 06:14:40.365 194-194/? I/AudioFlinger: Using default 3000 mSec as standby time.
10-06 06:14:46.664 194-194/? I/AudioPolicyService: AudioPolicyService CSTOR in new mode
10-06 06:14:46.673 194-194/? I/APM::ConfigParsingUtils: loadAudioPolicyConfig() loaded /system/etc/audio_policy.conf
10-06 06:14:46.681 194-194/? D/audio_hw_primary: adev_open: enter
10-06 06:14:46.797 194-194/? I/AudioFlinger: loadHwModule() Loaded primary audio interface from QCOM Audio HAL (audio) handle 1
10-06 06:14:46.797 194-194/? I/AudioFlinger: openOutput(), module 1 Device 2, SamplingRate 48000, Format 0x000001, Channels 3, flags 2
10-06 06:14:46.797 194-194/? I/AudioFlinger: AudioStreamOut::open(), mHalFormatIsLinearPcm = 1
10-06 06:14:46.798 194-194/? I/AudioFlinger: HAL output buffer size 240 frames, normal sink buffer size 960 frames
10-06 06:14:46.813 194-194/? I/AudioFlinger: Using module 1 has the primary audio interface
10-06 06:14:46.816 194-607/? I/AudioFlinger: AudioFlinger's thread 0xb4140000 ready to run
10-06 06:14:46.816 194-607/? D/audio_hw_primary: out_set_parameters: enter: usecase(1: low-latency-playback) kvpairs: routing=2
10-06 06:14:46.818 194-194/? I/AudioFlinger: openOutput(), module 1 Device 2, SamplingRate 48000, Format 0x000001, Channels 3, flags 8
10-06 06:14:46.818 194-194/? I/AudioFlinger: AudioStreamOut::open(), mHalFormatIsLinearPcm = 1
10-06 06:14:46.818 194-194/? I/AudioFlinger: HAL output buffer size 960 frames, normal sink buffer size 960 frames
10-06 06:14:46.818 194-608/? I/AudioFlinger: AudioFlinger's thread 0xb3dc0000 ready to run
10-06 06:14:46.818 194-607/? E/AudioFlinger: no wake lock to update!
10-06 06:14:46.818 194-608/? D/audio_hw_primary: out_set_parameters: enter: usecase(0: deep-buffer-playback) kvpairs: routing=2
10-06 06:14:46.818 194-608/? E/AudioFlinger: no wake lock to update!
10-06 06:14:46.820 194-609/? I/AudioFlinger: AudioFlinger's thread 0xb3c40000 ready to run
10-06 06:14:46.823 194-194/? I/AudioFlinger: loadHwModule() Loaded a2dp audio interface from A2DP Audio HW HAL (audio) handle 7
10-06 06:14:46.828 194-194/? I/AudioFlinger: loadHwModule() Loaded usb audio interface from USB audio HW HAL (audio) handle 8
10-06 06:14:46.832 194-194/? I/r_submix: adev_open(name=audio_hw_if)
10-06 06:14:46.832 194-194/? I/AudioFlinger: loadHwModule() Loaded r_submix audio interface from Wifi Display audio HAL (audio) handle 9
10-06 06:14:46.832 194-194/? D/r_submix: submix_audio_device_create_pipe_l(addr=0, idx=9)
10-06 06:14:46.833 194-610/? I/AudioFlinger: AudioFlinger's thread 0xb3bc0000 ready to run
10-06 06:14:46.833 194-194/? D/r_submix: submix_audio_device_release_pipe_l(idx=9) addr=0
10-06 06:14:46.833 194-194/? D/r_submix: submix_audio_device_destroy_pipe_l(): pipe destroyed
10-06 06:14:46.835 194-194/? D/audio_vloop: adev_open: audio_hw_if
10-06 06:14:46.835 194-194/? D/audio_vloop: adev_open(): 1678
10-06 06:14:46.835 194-194/? D/audio_vloop: adev_open(): 1685
10-06 06:14:46.835 194-194/? D/audio_vloop: adev_open(): 1688
10-06 06:14:46.835 194-194/? D/audio_vloop: adev_open(): 1722
10-06 06:14:46.835 194-194/? D/audio_vloop: adev_init_check(): 1252
10-06 06:14:46.835 194-194/? D/audio_vloop: adev_set_master_volume: 1.000000
10-06 06:14:46.835 194-194/? D/audio_vloop: adev_set_master_mute: 0
10-06 06:14:46.835 194-194/? I/AudioFlinger: loadHwModule() Loaded vloop audio interface from UI_audio_HW_HAL (audio) handle 11
10-06 06:14:46.835 194-194/? D/audio_vloop: adev_open_input_stream(): 1490
10-06 06:14:46.835 194-194/? D/audio_vloop: in_get_sample_rate(): 979
10-06 06:14:46.835 194-194/? D/audio_vloop: in_get_channels(): 1017
10-06 06:14:46.835 194-194/? D/audio_vloop: in_get_channels: 0x00000001
10-06 06:14:46.835 194-194/? D/audio_vloop: in_get_format(): 1029
10-06 06:14:46.836 194-194/? D/audio_vloop: in_get_format: 0x00000001
10-06 06:14:46.836 194-194/? D/audio_vloop: in_get_format(): 1029
10-06 06:14:46.836 194-194/? D/audio_vloop: in_get_format: 0x00000001
10-06 06:14:46.836 194-194/? D/audio_vloop: in_get_channels(): 1017
10-06 06:14:46.836 194-194/? D/audio_vloop: in_get_channels: 0x00000001
10-06 06:14:46.836 194-194/? D/audio_vloop: in_get_buffer_size(): 1005
10-06 06:14:46.836 194-194/? D/audio_vloop: in_get_buffer_size: 1600
10-06 06:14:46.836 194-194/? D/audio_vloop: in_get_buffer_size(): 1005
10-06 06:14:46.836 194-194/? D/audio_vloop: in_get_buffer_size: 1600
10-06 06:14:46.836 194-194/? D/audio_vloop: in_get_format(): 1029
10-06 06:14:46.836 194-194/? D/audio_vloop: in_get_format: 0x00000001
10-06 06:14:46.836 194-194/? D/audio_vloop: in_get_sample_rate(): 979
10-06 06:14:46.836 194-194/? D/audio_vloop: in_get_channels(): 1017
10-06 06:14:46.836 194-194/? D/audio_vloop: in_get_channels: 0x00000001
10-06 06:14:46.838 194-613/? I/AudioFlinger: AudioFlinger's thread 0xb3bc0000 ready to run
10-06 06:14:46.838 194-194/? D/audio_vloop: adev_close_input_stream(): 1570
10-06 06:14:46.839 194-194/? W/APM::AudioPolicyManager: Input device 00020000 unreachable
10-06 06:14:46.839 194-611/? D/audio_vloop: looper_thread(): 216: Entered
10-06 06:14:46.839 194-611/? D/audio_vloop: looper_thread(): 366: Exiting
10-06 06:15:07.137 616-616/? I/InputManager: Initializing input manager, mUseDevInputEventForAudioJack=false
10-06 06:15:10.155 616-616/? I/SystemServer: Audio Service
10-06 06:15:10.222 194-607/? E/AudioFlinger: no wake lock to update!
10-06 06:15:10.222 194-608/? E/AudioFlinger: no wake lock to update!
10-06 06:15:10.224 194-614/? D/audio_hw_primary: adev_set_mic_mute: state 0
10-06 06:15:10.224 194-614/? D/audio_vloop: adev_set_mic_mute: 0
10-06 06:15:14.061 194-614/? D/audio_hw_primary: adev_set_parameters: enter: A2dpSuspended=false
10-06 06:15:14.061 194-614/? D/audio_vloop: adev_set_parameters(): [A2dpSuspended=false]
10-06 06:15:14.084 194-194/? I/AudioFlinger: systemReady
10-06 06:15:16.308 194-194/? D/audio_hw_primary: adev_set_mic_mute: state 0
10-06 06:15:16.308 194-194/? D/audio_vloop: adev_set_mic_mute: 0
10-06 06:15:17.072 194-194/? D/audio_hw_primary: adev_set_parameters: enter: A2dpSuspended=false
10-06 06:15:17.072 194-194/? D/audio_vloop: adev_set_parameters(): [A2dpSuspended=false]
10-06 06:15:25.023 733-733/? W/AudioTrack: AUDIO_OUTPUT_FLAG_FAST denied by client; transfer 4, track 44100 Hz, output 48000 Hz
10-06 06:15:25.032 194-607/? D/audio_hw_primary: out_set_parameters: enter: usecase(1: low-latency-playback) kvpairs: routing=2
10-06 06:15:25.043 194-607/? D/audio_hw_primary: select_devices: out_snd_device(2: speaker) in_snd_device(0: none)
10-06 06:15:25.043 194-607/? D/audio_hw_primary: enable_snd_device: snd_device(2: speaker)
10-06 06:15:25.050 194-607/? D/audio_hw_primary: enable_audio_route: apply and update mixer path: low-latency-playback
10-06 06:15:26.431 1150-1298/? I/MicrophoneInputStream: mic_starting com.google.android.apps.gsa.speech.audio.ag@c6eb0e1
10-06 06:15:26.443 194-1585/? I/AudioFlinger: AudioFlinger's thread 0xb3bc0000 ready to run
10-06 06:15:26.447 1150-1298/? I/MicrophoneInputStream: mic_started com.google.android.apps.gsa.speech.audio.ag@c6eb0e1
10-06 06:15:26.457 194-1585/? D/audio_hw_primary: select_devices: out_snd_device(0: none) in_snd_device(38: voice-rec-mic)
10-06 06:15:26.457 194-1585/? D/audio_hw_primary: enable_snd_device: snd_device(38: voice-rec-mic)
10-06 06:15:26.460 194-1585/? D/audio_hw_primary: enable_audio_route: apply and update mixer path: audio-record
10-06 06:15:26.942 1150-1271/? I/AudioController: internalShutdown
10-06 06:15:26.943 1150-1271/? I/MicrophoneInputStream: mic_close com.google.android.apps.gsa.speech.audio.ag@c6eb0e1
10-06 06:15:26.943 1150-1298/? E/AudioRecord-JNI: Error -4 during AudioRecord native read
10-06 06:15:26.986 194-1585/? D/audio_hw_primary: disable_audio_route: reset and update mixer path: audio-record
10-06 06:15:26.987 194-1585/? D/audio_hw_primary: disable_snd_device: snd_device(38: voice-rec-mic)
10-06 06:15:27.066 194-607/? D/audio_hw_primary: out_set_parameters: enter: usecase(1: low-latency-playback) kvpairs: routing=2
10-06 06:15:27.100 194-607/? D/AudioFlinger: mixer(0xb4140000) throttle end: throttle time(7)
10-06 06:15:30.257 194-607/? D/audio_hw_primary: disable_audio_route: reset and update mixer path: low-latency-playback
10-06 06:15:30.257 194-607/? D/audio_hw_primary: disable_snd_device: snd_device(2: speaker)
10-06 06:15:30.262 194-607/? D/audio_hw_primary: out_set_parameters: enter: usecase(1: low-latency-playback) kvpairs: routing=2
10-06 06:15:30.272 194-607/? D/audio_hw_primary: select_devices: out_snd_device(2: speaker) in_snd_device(0: none)
10-06 06:15:30.273 194-607/? D/audio_hw_primary: enable_snd_device: snd_device(2: speaker)
10-06 06:15:30.280 194-607/? D/audio_hw_primary: enable_audio_route: apply and update mixer path: low-latency-playback
10-06 06:15:30.347 194-607/? D/AudioFlinger: mixer(0xb4140000) throttle end: throttle time(10)
10-06 06:15:31.517 194-607/? D/audio_hw_primary: out_set_parameters: enter: usecase(1: low-latency-playback) kvpairs: routing=2
10-06 06:15:31.751 1150-1298/? I/MicrophoneInputStream: mic_starting com.google.android.apps.gsa.speech.audio.ag@dd13203
10-06 06:15:31.762 194-1826/? I/AudioFlinger: AudioFlinger's thread 0xb3bc0000 ready to run
10-06 06:15:31.771 1150-1298/? I/MicrophoneInputStream: mic_started com.google.android.apps.gsa.speech.audio.ag@dd13203
10-06 06:15:31.780 194-1826/? D/audio_hw_primary: select_devices: out_snd_device(0: none) in_snd_device(38: voice-rec-mic)
10-06 06:15:31.780 194-1826/? D/audio_hw_primary: enable_snd_device: snd_device(38: voice-rec-mic)
10-06 06:15:31.783 194-1826/? D/audio_hw_primary: enable_audio_route: apply and update mixer path: audio-record
10-06 06:15:34.695 194-607/? D/audio_hw_primary: disable_audio_route: reset and update mixer path: low-latency-playback
10-06 06:15:34.695 194-607/? D/audio_hw_primary: disable_snd_device: snd_device(2: speaker)
10-06 06:15:34.850 1150-1271/? I/AudioController: internalShutdown
10-06 06:15:34.851 1150-1271/? I/MicrophoneInputStream: mic_close com.google.android.apps.gsa.speech.audio.ag@dd13203
10-06 06:15:34.851 1150-1298/? E/AudioRecord-JNI: Error -4 during AudioRecord native read
10-06 06:15:34.885 194-1826/? D/audio_hw_primary: disable_audio_route: reset and update mixer path: audio-record
10-06 06:15:34.885 194-1826/? D/audio_hw_primary: disable_snd_device: snd_device(38: voice-rec-mic)

我的是audio_vloop。我可以看到Android打开我的设备，然后打开输入流，然后关闭输入流。它从不试图打开输出流。 audio_vloop实现输入和输出流。在此之后，Android中不会调用audio_vloop中的任何内容。

我制作了一个播放音频的小应用程序（暂时来自pcm文件）。我想将此输出重定向到我的HAL。为了达到这个目的，我相信我需要在我的音轨上做一个AudioTrack.setPreferredDevice（）。我发现音频管理器应该有一个所有音频设备的列表。

所以我打电话给：

AudioDeviceInfo aDevInfo[] = am.getDevices(AudioManager.GET_DEVICES_OUTPUTS);

它只能找到1台设备，此设备上有更多信息：

10-06 06:37:01.962 3295-3663/? D/AudioPlayer: Have [1] devices
10-06 06:37:01.964 3295-3663/? D/AudioPlayer: devInfo[0]: [Landroid.media.AudioDeviceInfo;@90bd9da
10-06 06:37:01.965 3295-3663/? D/AudioPlayer: getProductName()AOSP on Flo
10-06 06:37:01.965 3295-3663/? D/AudioPlayer: getType()2
10-06 06:37:01.966 3295-3663/? D/AudioPlayer: isSink()true
10-06 06:37:01.966 3295-3663/? D/AudioPlayer: isSource()false

这似乎来自audioPort，我还没有实现。所以它不是来自我的HAL。

在Android允许我的应用与我的设备通信之前，我显然错过了一个或多个步骤。

我需要能够将应用程序中的音频发送到我的HAL中。之后，我还需要能够从我的HAL（通过AudioRecord等）接收音频。

将HAL集成到Android中我错过了什么？我需要实现音频端口吗？还需要其他东西吗？

更新2

我在AudioPolicyManager.cpp@2922

中发现AOSP中存在拼写错误

而不是Output，它会打印Input

我有这个日志AudioPolicyManager: Input device 00020000 unreachable我忽略了假设它正在谈论BT / A2DP输入设备。

我修复了设备的日志，结果是我们想要使用的Line out设备。我现在正在调试这个方向。

Answer 1

找到答案。

对于外线：

Android

AUDIO_CHANNEL_OUT_STEREO

Android自动无法打开提及标记AUDIO_OUTPUT_FLAG_DIRECT的输出。这在以下AudioPolicyManager.cpp
中的代码中很明显
```
    if ((outProfile->mFlags & AUDIO_OUTPUT_FLAG_DIRECT) != 0) {
        continue;
    }
```
来自here

可能有办法以编程方式打开它们，但我还没有找到答案。

这两个，一旦修复就足以让Android开始使用我的输出流。

for in stream：

在流中已经是AudioManager.getDevices()

因此可以在AudioTrack.setPreferredDevice()之后从流中读取vloop。

为了确保其他应用程序能够从vloop读取麦克风输入，我必须声明它来实现AUDIO_DEVICE_IN_BUILTIN_MIC。为此，我还从AUDIO_DEVICE_IN_BUILTIN_MIC中的主HAL中删除了audio_policy.conf。

此外，我只使用流式立体声来保持与流式缓冲格式的兼容性。

经过这些更改后，我发现有连续的读写调用进入vloop。

<强>更新

我后来发现上面提到的行为取决于Audio Policy Manager的实现。它们中的大多数行为相同（例如，大多数开放的INBUILT_MIC用于VOICE_RECOGNITION输入）但有些可能不是（Nexus Player）对于这些异常值，要么实现其APM打开，要么修改APM以打开HAL实现的内容。

使Android使用新的Audio HAL需要什么

1 个答案: