root/media/audio/win/device_enumeration_win.cc

DEFINITIONS

1. GetDeviceNamesWinImpl
2. GetDeviceNamesWinXPImpl
3. GetInputDeviceNamesWin
4. GetOutputDeviceNamesWin
5. GetInputDeviceNamesWinXP
6. GetOutputDeviceNamesWinXP
7. ConvertToWinXPInputDeviceId

// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include <MMDeviceAPI.h>
#include <mmsystem.h>
#include <Functiondiscoverykeys_devpkey.h>  // MMDeviceAPI.h must come first

#include "media/audio/win/audio_manager_win.h"

#include "base/basictypes.h"
#include "base/logging.h"
#include "base/strings/utf_string_conversions.h"
#include "base/win/scoped_co_mem.h"
#include "base/win/scoped_comptr.h"
#include "base/win/scoped_propvariant.h"

using base::win::ScopedComPtr;
using base::win::ScopedCoMem;

// Taken from Mmddk.h.
#define DRV_RESERVED                      0x0800
#define DRV_QUERYFUNCTIONINSTANCEID       (DRV_RESERVED + 17)
#define DRV_QUERYFUNCTIONINSTANCEIDSIZE   (DRV_RESERVED + 18)

namespace media {

static bool GetDeviceNamesWinImpl(EDataFlow data_flow,
                                  AudioDeviceNames* device_names) {
  // It is assumed that this method is called from a COM thread, i.e.,
  // CoInitializeEx() is not called here again to avoid STA/MTA conflicts.
  ScopedComPtr<IMMDeviceEnumerator> enumerator;
  HRESULT hr = enumerator.CreateInstance(__uuidof(MMDeviceEnumerator), NULL,
                                         CLSCTX_INPROC_SERVER);
  DCHECK_NE(CO_E_NOTINITIALIZED, hr);
  if (FAILED(hr)) {
    LOG(WARNING) << "Failed to create IMMDeviceEnumerator: " << std::hex << hr;
    return false;
  }

  // Generate a collection of active audio endpoint devices.
  // This method will succeed even if all devices are disabled.
  ScopedComPtr<IMMDeviceCollection> collection;
  hr = enumerator->EnumAudioEndpoints(data_flow,
                                      DEVICE_STATE_ACTIVE,
                                      collection.Receive());
  if (FAILED(hr))
    return false;

  // Retrieve the number of active devices.
  UINT number_of_active_devices = 0;
  collection->GetCount(&number_of_active_devices);
  if (number_of_active_devices == 0)
    return true;

  AudioDeviceName device;

  // Loop over all active devices and add friendly name and
  // unique ID to the |device_names| list.
  for (UINT i = 0; i < number_of_active_devices; ++i) {
    // Retrieve unique name of endpoint device.
    // Example: "{0.0.1.00000000}.{8db6020f-18e3-4f25-b6f5-7726c9122574}".
    ScopedComPtr<IMMDevice> audio_device;
    hr = collection->Item(i, audio_device.Receive());
    if (FAILED(hr))
      continue;

    // Store the unique name.
    ScopedCoMem<WCHAR> endpoint_device_id;
    audio_device->GetId(&endpoint_device_id);
    device.unique_id =
        base::WideToUTF8(static_cast<WCHAR*>(endpoint_device_id));

    // Retrieve user-friendly name of endpoint device.
    // Example: "Microphone (Realtek High Definition Audio)".
    ScopedComPtr<IPropertyStore> properties;
    hr = audio_device->OpenPropertyStore(STGM_READ, properties.Receive());
    if (SUCCEEDED(hr)) {
      base::win::ScopedPropVariant friendly_name;
      hr = properties->GetValue(PKEY_Device_FriendlyName,
                                friendly_name.Receive());

      // Store the user-friendly name.
      if (SUCCEEDED(hr) &&
          friendly_name.get().vt == VT_LPWSTR && friendly_name.get().pwszVal) {
        device.device_name = base::WideToUTF8(friendly_name.get().pwszVal);
      }
    }

    // Add combination of user-friendly and unique name to the output list.
    device_names->push_back(device);
  }

  return true;
}

// The waveform API is weird in that it has completely separate but
// almost identical functions and structs for input devices vs. output
// devices. We deal with this by implementing the logic as a templated
// function that takes the functions and struct type to use as
// template parameters.
template <UINT (__stdcall *NumDevsFunc)(),
          typename CAPSSTRUCT,
          MMRESULT (__stdcall *DevCapsFunc)(UINT_PTR, CAPSSTRUCT*, UINT)>
static bool GetDeviceNamesWinXPImpl(AudioDeviceNames* device_names) {
  // Retrieve the number of active waveform input devices.
  UINT number_of_active_devices = NumDevsFunc();
  if (number_of_active_devices == 0)
    return true;

  AudioDeviceName device;
  CAPSSTRUCT capabilities;
  MMRESULT err = MMSYSERR_NOERROR;

  // Loop over all active capture devices and add friendly name and
  // unique ID to the |device_names| list. Note that, for Wave on XP,
  // the "unique" name will simply be a copy of the friendly name since
  // there is no safe method to retrieve a unique device name on XP.
  for (UINT i = 0; i < number_of_active_devices; ++i) {
    // Retrieve the capabilities of the specified waveform-audio input device.
    err = DevCapsFunc(i,  &capabilities, sizeof(capabilities));
    if (err != MMSYSERR_NOERROR)
      continue;

    // Store the user-friendly name. Max length is MAXPNAMELEN(=32)
    // characters and the name cane be truncated on XP.
    // Example: "Microphone (Realtek High Defini".
    device.device_name = base::WideToUTF8(capabilities.szPname);

    // Store the "unique" name (we use same as friendly name on Windows XP).
    device.unique_id = device.device_name;

    // Add combination of user-friendly and unique name to the output list.
    device_names->push_back(device);
  }

  return true;
}

bool GetInputDeviceNamesWin(AudioDeviceNames* device_names) {
  return GetDeviceNamesWinImpl(eCapture, device_names);
}

bool GetOutputDeviceNamesWin(AudioDeviceNames* device_names) {
  return GetDeviceNamesWinImpl(eRender, device_names);
}

bool GetInputDeviceNamesWinXP(AudioDeviceNames* device_names) {
  return GetDeviceNamesWinXPImpl<
      waveInGetNumDevs, WAVEINCAPSW, waveInGetDevCapsW>(device_names);
}

bool GetOutputDeviceNamesWinXP(AudioDeviceNames* device_names) {
  return GetDeviceNamesWinXPImpl<
      waveOutGetNumDevs, WAVEOUTCAPSW, waveOutGetDevCapsW>(device_names);
}

std::string ConvertToWinXPInputDeviceId(const std::string& device_id) {
  UINT number_of_active_devices = waveInGetNumDevs();
  MMRESULT result = MMSYSERR_NOERROR;

  UINT i = 0;
  for (; i < number_of_active_devices; ++i) {
    size_t size = 0;
    // Get the size (including the terminating NULL) of the endpoint ID of the
    // waveIn device.
    result = waveInMessage(reinterpret_cast<HWAVEIN>(i),
                           DRV_QUERYFUNCTIONINSTANCEIDSIZE,
                           reinterpret_cast<DWORD_PTR>(&size), NULL);
    if (result != MMSYSERR_NOERROR)
      continue;

    ScopedCoMem<WCHAR> id;
    id.Reset(static_cast<WCHAR*>(CoTaskMemAlloc(size)));
    if (!id)
      continue;

    // Get the endpoint ID string for this waveIn device.
    result = waveInMessage(
        reinterpret_cast<HWAVEIN>(i), DRV_QUERYFUNCTIONINSTANCEID,
        reinterpret_cast<DWORD_PTR>(static_cast<WCHAR*>(id)), size);
    if (result != MMSYSERR_NOERROR)
      continue;

    std::string utf8_id = base::WideToUTF8(static_cast<WCHAR*>(id));
    // Check whether the endpoint ID string of this waveIn device matches that
    // of the audio endpoint device.
    if (device_id == utf8_id)
      break;
  }

  // If a matching waveIn device was found, convert the unique endpoint ID
  // string to a standard friendly name with max 32 characters.
  if (i < number_of_active_devices) {
    WAVEINCAPS capabilities;

    result = waveInGetDevCaps(i, &capabilities, sizeof(capabilities));
    if (result == MMSYSERR_NOERROR)
      return base::WideToUTF8(capabilities.szPname);
  }

  return std::string();
}

}  // namespace media