安卓框架，新增usb mic device 的框架修改

新增usb mic还涉及到了音频部分，先看下audio_policy.conf

  usb {
    outputs {
      usb_accessory {
        sampling_rates 44100
        channel_masks AUDIO_CHANNEL_OUT_STEREO
        formats AUDIO_FORMAT_PCM_16_BIT
        devices AUDIO_DEVICE_OUT_USB_ACCESSORY
      }
      usb_device {
        sampling_rates dynamic
        channel_masks dynamic
        formats dynamic
        devices AUDIO_DEVICE_OUT_USB_DEVICE
      }
    }
    inputs {
      usb_device {
        sampling_rates dynamic
        channel_masks dynamic
        formats dynamic
        devices AUDIO_DEVICE_IN_USB_DEVICE
      }
    }
  }

关注点：
1.比如你的android手机做host，要获得slave，用UsbDevice表示slave
要是你的android手机做slave，要获得host，用UsbAccessory表示host

2.输入输出设备必须是audio.h中列出的枚举类型

3”channel_masks”、”formats”、”devices”和”flags”必须为audio.h、audio_policy.h中定义的枚
举值，它们可以通过|连接，但不能包含空格和”\n”。

接着模仿新增一个usb

 usb2 {
//其它不做说明
    inputs {
      usb_device {
        sampling_rates dynamic
        channel_masks dynamic
        formats dynamic
        devices AUDIO_DEVICE_IN_USB_DEVICE |AUDIO_DEVICE_IN_USB_DEVICE_TYPE2
      }
    }
  }

之前说devices 在audio.h、audio_policy.h中有对应，一搜AUDIO_DEVICE_IN_USB_DEVICE 果然在audio.h

audio.h

  AUDIO_DEVICE_IN_USB_DEVICE            = AUDIO_DEVICE_BIT_IN | 0x1000,
    在后面新增
    AUDIO_DEVICE_IN_USB_DEVICE_TYPE2=  AUDIO_DEVICE_BIT_IN | 0x80,

AudioPolicyManager.cpp文件会加载audio_policy.conf,也需新增参数

const StringToEnum sDeviceNameToEnumTable[] = {
    STRING_TO_ENUM(AUDIO_DEVICE_IN_DGTL_DOCK_HEADSET),
    STRING_TO_ENUM(AUDIO_DEVICE_IN_USB_ACCESSORY),
    STRING_TO_ENUM(AUDIO_DEVICE_IN_USB_DEVICE),    
   // 新增AUDIO_DEVICE_IN_USB_DEVICE_TYPE2
     STRING_TO_ENUM(AUDIO_DEVICE_IN_USB_DEVICE_TYPE2),
}


audio_devices_t AudioPolicyManager::getDeviceForInputSource 中新增判断AUDIO_DEVICE_IN_USB_DEVICE_TYPE2的方法，模仿AUDIO_DEVICE_IN_USB_DEVICE 的做法就对了

AudioSystem.java 也有对应的比特位

// reserved bits
public static final int DEVICE_BIT_IN = 0x80000000;

对应audio.h的
/* reserved bits */
AUDIO_DEVICE_BIT_IN = 0x80000000,

AUDIO_DEVICE_IN_USB_DEVICE_TYPE2= AUDIO_DEVICE_BIT_IN | 0x80,
所以java端的新增是
AUDIO_DEVICE_IN_USB_DEVICE_TYPE2 = DEVICE_BIT_IN | 0x80,

编译成so库
android-5.1.1/hardware/libhardware/modules/usbaudio/Android.mk

LOCAL_MODULE := audio.usb.default
LOCAL_MODULE_RELATIVE_PATH := hw
LOCAL_SRC_FILES := \
    audio_hw.c \
    alsa_device_profile.c \
    alsa_device_proxy.c \
    logging.c \
    format.c
LOCAL_C_INCLUDES += \
    external/tinyalsa/include \
    $(call include-path-for, audio-utils)
LOCAL_SHARED_LIBRARIES := liblog libcutils libtinyalsa libaudioutils
LOCAL_MODULE_TAGS := optional
LOCAL_CFLAGS := -Wno-unused-parameter

include $(BUILD_SHARED_LIBRARY)

include $(CLEAR_VARS)

LOCAL_MODULE := audio.usb2.default
LOCAL_MODULE_RELATIVE_PATH := hw
LOCAL_SRC_FILES := \
    audio_hw.c \
    alsa_device_profile.c \
    alsa_device_proxy.c \
    logging.c \
    format.c
LOCAL_C_INCLUDES += \
    external/tinyalsa/include \
    $(call include-path-for, audio-utils)
LOCAL_SHARED_LIBRARIES := liblog libcutils libtinyalsa libaudioutils
LOCAL_MODULE_TAGS := optional
LOCAL_CFLAGS := -Wno-unused-parameter

include $(BUILD_SHARED_LIBRARY)

最后不要忘记
android-5.1.1/device/xxxx/xxxx/device.mk

PRODUCT_PACKAGES += \
        audio.a2dp.default \
        audio.usb.default \
        audio.usb2.default \

补充：
判断声卡的方法

UsbAudioManager.java void deviceAdded 这里会调用区分声卡的方法

AlsaDevicesParser.java
public void scan() {
deviceRecords_.clear();

    final String devicesFilePath = "/proc/asound/devices";
    File devicesFile = new File(devicesFilePath);
    try {
        FileReader reader = new FileReader(devicesFile);
        BufferedReader bufferedReader = new BufferedReader(reader);
        String line = "";
        while ((line = bufferedReader.readLine()) != null) {
            if (isLineDeviceRecord(line)) {
                AlsaDeviceRecord deviceRecord = new AlsaDeviceRecord();
                deviceRecord.parse(line);
                deviceRecords_.add(deviceRecord);
            }
        }
        reader.close();
    } catch (FileNotFoundException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }
}

涉及到的类
android-5.1.1/device/XXX/XXX/audio_policy.conf
android-5.1.1/device/XXXX/XXXX/device.mk
android-5.1.1/frameworks/av/services/audiopolicy/AudioPolicyManager.cpp
android-5.1.1/frameworks/base/media/java/android/media/AudioService.java
android-5.1.1/frameworks/base/media/java/android/media/AudioSystem.java
android-5.1.1/frameworks/base/services/usb/java/com/android/server/usb/UsbAudioManager.java
android-5.1.1/hardware/libhardware/modules/usbaudio/Android.mk
android-5.1.1/system/core/include/system/audio.h