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      1 /*
      2  * Copyright (C) 2008 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 #ifndef ANDROID_AUDIOSYSTEM_H_
     18 #define ANDROID_AUDIOSYSTEM_H_
     19 
     20 #include <utils/RefBase.h>
     21 #include <utils/threads.h>
     22 #include <media/IAudioFlinger.h>
     23 
     24 namespace android {
     25 
     26 typedef void (*audio_error_callback)(status_t err);
     27 typedef int audio_io_handle_t;
     28 
     29 class IAudioPolicyService;
     30 class String8;
     31 
     32 class AudioSystem
     33 {
     34 public:
     35 
     36     enum stream_type {
     37         DEFAULT          =-1,
     38         VOICE_CALL       = 0,
     39         SYSTEM           = 1,
     40         RING             = 2,
     41         MUSIC            = 3,
     42         ALARM            = 4,
     43         NOTIFICATION     = 5,
     44         BLUETOOTH_SCO    = 6,
     45         ENFORCED_AUDIBLE = 7, // Sounds that cannot be muted by user and must be routed to speaker
     46         DTMF             = 8,
     47         TTS              = 9,
     48         NUM_STREAM_TYPES
     49     };
     50 
     51     // Audio sub formats (see AudioSystem::audio_format).
     52     enum pcm_sub_format {
     53         PCM_SUB_16_BIT          = 0x1, // must be 1 for backward compatibility
     54         PCM_SUB_8_BIT           = 0x2, // must be 2 for backward compatibility
     55     };
     56 
     57     // MP3 sub format field definition : can use 11 LSBs in the same way as MP3 frame header to specify
     58     // bit rate, stereo mode, version...
     59     enum mp3_sub_format {
     60         //TODO
     61     };
     62 
     63     // AMR NB/WB sub format field definition: specify frame block interleaving, bandwidth efficient or octet aligned,
     64     // encoding mode for recording...
     65     enum amr_sub_format {
     66         //TODO
     67     };
     68 
     69     // AAC sub format field definition: specify profile or bitrate for recording...
     70     enum aac_sub_format {
     71         //TODO
     72     };
     73 
     74     // VORBIS sub format field definition: specify quality for recording...
     75     enum vorbis_sub_format {
     76         //TODO
     77     };
     78 
     79     // Audio format consists in a main format field (upper 8 bits) and a sub format field (lower 24 bits).
     80     // The main format indicates the main codec type. The sub format field indicates options and parameters
     81     // for each format. The sub format is mainly used for record to indicate for instance the requested bitrate
     82     // or profile. It can also be used for certain formats to give informations not present in the encoded
     83     // audio stream (e.g. octet alignement for AMR).
     84     enum audio_format {
     85         INVALID_FORMAT      = -1,
     86         FORMAT_DEFAULT      = 0,
     87         PCM                 = 0x00000000, // must be 0 for backward compatibility
     88         MP3                 = 0x01000000,
     89         AMR_NB              = 0x02000000,
     90         AMR_WB              = 0x03000000,
     91         AAC                 = 0x04000000,
     92         HE_AAC_V1           = 0x05000000,
     93         HE_AAC_V2           = 0x06000000,
     94         VORBIS              = 0x07000000,
     95         MAIN_FORMAT_MASK    = 0xFF000000,
     96         SUB_FORMAT_MASK     = 0x00FFFFFF,
     97         // Aliases
     98         PCM_16_BIT          = (PCM|PCM_SUB_16_BIT),
     99         PCM_8_BIT          = (PCM|PCM_SUB_8_BIT)
    100     };
    101 
    102 
    103     // Channel mask definitions must be kept in sync with JAVA values in /media/java/android/media/AudioFormat.java
    104     enum audio_channels {
    105         // output channels
    106         CHANNEL_OUT_FRONT_LEFT = 0x4,
    107         CHANNEL_OUT_FRONT_RIGHT = 0x8,
    108         CHANNEL_OUT_FRONT_CENTER = 0x10,
    109         CHANNEL_OUT_LOW_FREQUENCY = 0x20,
    110         CHANNEL_OUT_BACK_LEFT = 0x40,
    111         CHANNEL_OUT_BACK_RIGHT = 0x80,
    112         CHANNEL_OUT_FRONT_LEFT_OF_CENTER = 0x100,
    113         CHANNEL_OUT_FRONT_RIGHT_OF_CENTER = 0x200,
    114         CHANNEL_OUT_BACK_CENTER = 0x400,
    115         CHANNEL_OUT_MONO = CHANNEL_OUT_FRONT_LEFT,
    116         CHANNEL_OUT_STEREO = (CHANNEL_OUT_FRONT_LEFT | CHANNEL_OUT_FRONT_RIGHT),
    117         CHANNEL_OUT_QUAD = (CHANNEL_OUT_FRONT_LEFT | CHANNEL_OUT_FRONT_RIGHT |
    118                 CHANNEL_OUT_BACK_LEFT | CHANNEL_OUT_BACK_RIGHT),
    119         CHANNEL_OUT_SURROUND = (CHANNEL_OUT_FRONT_LEFT | CHANNEL_OUT_FRONT_RIGHT |
    120                 CHANNEL_OUT_FRONT_CENTER | CHANNEL_OUT_BACK_CENTER),
    121         CHANNEL_OUT_5POINT1 = (CHANNEL_OUT_FRONT_LEFT | CHANNEL_OUT_FRONT_RIGHT |
    122                 CHANNEL_OUT_FRONT_CENTER | CHANNEL_OUT_LOW_FREQUENCY | CHANNEL_OUT_BACK_LEFT | CHANNEL_OUT_BACK_RIGHT),
    123         CHANNEL_OUT_7POINT1 = (CHANNEL_OUT_FRONT_LEFT | CHANNEL_OUT_FRONT_RIGHT |
    124                 CHANNEL_OUT_FRONT_CENTER | CHANNEL_OUT_LOW_FREQUENCY | CHANNEL_OUT_BACK_LEFT | CHANNEL_OUT_BACK_RIGHT |
    125                 CHANNEL_OUT_FRONT_LEFT_OF_CENTER | CHANNEL_OUT_FRONT_RIGHT_OF_CENTER),
    126         CHANNEL_OUT_ALL = (CHANNEL_OUT_FRONT_LEFT | CHANNEL_OUT_FRONT_RIGHT |
    127                 CHANNEL_OUT_FRONT_CENTER | CHANNEL_OUT_LOW_FREQUENCY | CHANNEL_OUT_BACK_LEFT | CHANNEL_OUT_BACK_RIGHT |
    128                 CHANNEL_OUT_FRONT_LEFT_OF_CENTER | CHANNEL_OUT_FRONT_RIGHT_OF_CENTER | CHANNEL_OUT_BACK_CENTER),
    129 
    130         // input channels
    131         CHANNEL_IN_LEFT = 0x4,
    132         CHANNEL_IN_RIGHT = 0x8,
    133         CHANNEL_IN_FRONT = 0x10,
    134         CHANNEL_IN_BACK = 0x20,
    135         CHANNEL_IN_LEFT_PROCESSED = 0x40,
    136         CHANNEL_IN_RIGHT_PROCESSED = 0x80,
    137         CHANNEL_IN_FRONT_PROCESSED = 0x100,
    138         CHANNEL_IN_BACK_PROCESSED = 0x200,
    139         CHANNEL_IN_PRESSURE = 0x400,
    140         CHANNEL_IN_X_AXIS = 0x800,
    141         CHANNEL_IN_Y_AXIS = 0x1000,
    142         CHANNEL_IN_Z_AXIS = 0x2000,
    143         CHANNEL_IN_VOICE_UPLINK = 0x4000,
    144         CHANNEL_IN_VOICE_DNLINK = 0x8000,
    145         CHANNEL_IN_MONO = CHANNEL_IN_FRONT,
    146         CHANNEL_IN_STEREO = (CHANNEL_IN_LEFT | CHANNEL_IN_RIGHT),
    147         CHANNEL_IN_ALL = (CHANNEL_IN_LEFT | CHANNEL_IN_RIGHT | CHANNEL_IN_FRONT | CHANNEL_IN_BACK|
    148                 CHANNEL_IN_LEFT_PROCESSED | CHANNEL_IN_RIGHT_PROCESSED | CHANNEL_IN_FRONT_PROCESSED | CHANNEL_IN_BACK_PROCESSED|
    149                 CHANNEL_IN_PRESSURE | CHANNEL_IN_X_AXIS | CHANNEL_IN_Y_AXIS | CHANNEL_IN_Z_AXIS |
    150                 CHANNEL_IN_VOICE_UPLINK | CHANNEL_IN_VOICE_DNLINK)
    151     };
    152 
    153     enum audio_mode {
    154         MODE_INVALID = -2,
    155         MODE_CURRENT = -1,
    156         MODE_NORMAL = 0,
    157         MODE_RINGTONE,
    158         MODE_IN_CALL,
    159         NUM_MODES  // not a valid entry, denotes end-of-list
    160     };
    161 
    162     enum audio_in_acoustics {
    163         AGC_ENABLE    = 0x0001,
    164         AGC_DISABLE   = 0,
    165         NS_ENABLE     = 0x0002,
    166         NS_DISABLE    = 0,
    167         TX_IIR_ENABLE = 0x0004,
    168         TX_DISABLE    = 0
    169     };
    170 
    171     // special audio session values
    172     enum audio_sessions {
    173         SESSION_OUTPUT_STAGE = -1, // session for effects attached to a particular output stream
    174                                    // (value must be less than 0)
    175         SESSION_OUTPUT_MIX = 0,    // session for effects applied to output mix. These effects can
    176                                    // be moved by audio policy manager to another output stream
    177                                    // (value must be 0)
    178     };
    179 
    180     /* These are static methods to control the system-wide AudioFlinger
    181      * only privileged processes can have access to them
    182      */
    183 
    184     // mute/unmute microphone
    185     static status_t muteMicrophone(bool state);
    186     static status_t isMicrophoneMuted(bool *state);
    187 
    188     // set/get master volume
    189     static status_t setMasterVolume(float value);
    190     static status_t getMasterVolume(float* volume);
    191     // mute/unmute audio outputs
    192     static status_t setMasterMute(bool mute);
    193     static status_t getMasterMute(bool* mute);
    194 
    195     // set/get stream volume on specified output
    196     static status_t setStreamVolume(int stream, float value, int output);
    197     static status_t getStreamVolume(int stream, float* volume, int output);
    198 
    199     // mute/unmute stream
    200     static status_t setStreamMute(int stream, bool mute);
    201     static status_t getStreamMute(int stream, bool* mute);
    202 
    203     // set audio mode in audio hardware (see AudioSystem::audio_mode)
    204     static status_t setMode(int mode);
    205 
    206     // returns true in *state if tracks are active on the specified stream
    207     static status_t isStreamActive(int stream, bool *state);
    208 
    209     // set/get audio hardware parameters. The function accepts a list of parameters
    210     // key value pairs in the form: key1=value1;key2=value2;...
    211     // Some keys are reserved for standard parameters (See AudioParameter class).
    212     static status_t setParameters(audio_io_handle_t ioHandle, const String8& keyValuePairs);
    213     static String8  getParameters(audio_io_handle_t ioHandle, const String8& keys);
    214 
    215     static void setErrorCallback(audio_error_callback cb);
    216 
    217     // helper function to obtain AudioFlinger service handle
    218     static const sp<IAudioFlinger>& get_audio_flinger();
    219 
    220     static float linearToLog(int volume);
    221     static int logToLinear(float volume);
    222 
    223     static status_t getOutputSamplingRate(int* samplingRate, int stream = DEFAULT);
    224     static status_t getOutputFrameCount(int* frameCount, int stream = DEFAULT);
    225     static status_t getOutputLatency(uint32_t* latency, int stream = DEFAULT);
    226 
    227     static bool routedToA2dpOutput(int streamType);
    228 
    229     static status_t getInputBufferSize(uint32_t sampleRate, int format, int channelCount,
    230         size_t* buffSize);
    231 
    232     static status_t setVoiceVolume(float volume);
    233 
    234     // return the number of audio frames written by AudioFlinger to audio HAL and
    235     // audio dsp to DAC since the output on which the specificed stream is playing
    236     // has exited standby.
    237     // returned status (from utils/Errors.h) can be:
    238     // - NO_ERROR: successful operation, halFrames and dspFrames point to valid data
    239     // - INVALID_OPERATION: Not supported on current hardware platform
    240     // - BAD_VALUE: invalid parameter
    241     // NOTE: this feature is not supported on all hardware platforms and it is
    242     // necessary to check returned status before using the returned values.
    243     static status_t getRenderPosition(uint32_t *halFrames, uint32_t *dspFrames, int stream = DEFAULT);
    244 
    245     static unsigned int  getInputFramesLost(audio_io_handle_t ioHandle);
    246 
    247     static int newAudioSessionId();
    248     //
    249     // AudioPolicyService interface
    250     //
    251 
    252     enum audio_devices {
    253         // output devices
    254         DEVICE_OUT_EARPIECE = 0x1,
    255         DEVICE_OUT_SPEAKER = 0x2,
    256         DEVICE_OUT_WIRED_HEADSET = 0x4,
    257         DEVICE_OUT_WIRED_HEADPHONE = 0x8,
    258         DEVICE_OUT_BLUETOOTH_SCO = 0x10,
    259         DEVICE_OUT_BLUETOOTH_SCO_HEADSET = 0x20,
    260         DEVICE_OUT_BLUETOOTH_SCO_CARKIT = 0x40,
    261         DEVICE_OUT_BLUETOOTH_A2DP = 0x80,
    262         DEVICE_OUT_BLUETOOTH_A2DP_HEADPHONES = 0x100,
    263         DEVICE_OUT_BLUETOOTH_A2DP_SPEAKER = 0x200,
    264         DEVICE_OUT_AUX_DIGITAL = 0x400,
    265         DEVICE_OUT_DEFAULT = 0x8000,
    266         DEVICE_OUT_ALL = (DEVICE_OUT_EARPIECE | DEVICE_OUT_SPEAKER | DEVICE_OUT_WIRED_HEADSET |
    267                 DEVICE_OUT_WIRED_HEADPHONE | DEVICE_OUT_BLUETOOTH_SCO | DEVICE_OUT_BLUETOOTH_SCO_HEADSET |
    268                 DEVICE_OUT_BLUETOOTH_SCO_CARKIT | DEVICE_OUT_BLUETOOTH_A2DP | DEVICE_OUT_BLUETOOTH_A2DP_HEADPHONES |
    269                 DEVICE_OUT_BLUETOOTH_A2DP_SPEAKER | DEVICE_OUT_AUX_DIGITAL | DEVICE_OUT_DEFAULT),
    270         DEVICE_OUT_ALL_A2DP = (DEVICE_OUT_BLUETOOTH_A2DP | DEVICE_OUT_BLUETOOTH_A2DP_HEADPHONES |
    271                 DEVICE_OUT_BLUETOOTH_A2DP_SPEAKER),
    272 
    273         // input devices
    274         DEVICE_IN_COMMUNICATION = 0x10000,
    275         DEVICE_IN_AMBIENT = 0x20000,
    276         DEVICE_IN_BUILTIN_MIC = 0x40000,
    277         DEVICE_IN_BLUETOOTH_SCO_HEADSET = 0x80000,
    278         DEVICE_IN_WIRED_HEADSET = 0x100000,
    279         DEVICE_IN_AUX_DIGITAL = 0x200000,
    280         DEVICE_IN_VOICE_CALL = 0x400000,
    281         DEVICE_IN_BACK_MIC = 0x800000,
    282         DEVICE_IN_DEFAULT = 0x80000000,
    283 
    284         DEVICE_IN_ALL = (DEVICE_IN_COMMUNICATION | DEVICE_IN_AMBIENT | DEVICE_IN_BUILTIN_MIC |
    285                 DEVICE_IN_BLUETOOTH_SCO_HEADSET | DEVICE_IN_WIRED_HEADSET | DEVICE_IN_AUX_DIGITAL |
    286                 DEVICE_IN_VOICE_CALL | DEVICE_IN_BACK_MIC | DEVICE_IN_DEFAULT)
    287     };
    288 
    289     // device connection states used for setDeviceConnectionState()
    290     enum device_connection_state {
    291         DEVICE_STATE_UNAVAILABLE,
    292         DEVICE_STATE_AVAILABLE,
    293         NUM_DEVICE_STATES
    294     };
    295 
    296     // request to open a direct output with getOutput() (by opposition to sharing an output with other AudioTracks)
    297     enum output_flags {
    298         OUTPUT_FLAG_INDIRECT = 0x0,
    299         OUTPUT_FLAG_DIRECT = 0x1
    300     };
    301 
    302     // device categories used for setForceUse()
    303     enum forced_config {
    304         FORCE_NONE,
    305         FORCE_SPEAKER,
    306         FORCE_HEADPHONES,
    307         FORCE_BT_SCO,
    308         FORCE_BT_A2DP,
    309         FORCE_WIRED_ACCESSORY,
    310         FORCE_BT_CAR_DOCK,
    311         FORCE_BT_DESK_DOCK,
    312         NUM_FORCE_CONFIG,
    313         FORCE_DEFAULT = FORCE_NONE
    314     };
    315 
    316     // usages used for setForceUse()
    317     enum force_use {
    318         FOR_COMMUNICATION,
    319         FOR_MEDIA,
    320         FOR_RECORD,
    321         FOR_DOCK,
    322         NUM_FORCE_USE
    323     };
    324 
    325     // types of io configuration change events received with ioConfigChanged()
    326     enum io_config_event {
    327         OUTPUT_OPENED,
    328         OUTPUT_CLOSED,
    329         OUTPUT_CONFIG_CHANGED,
    330         INPUT_OPENED,
    331         INPUT_CLOSED,
    332         INPUT_CONFIG_CHANGED,
    333         STREAM_CONFIG_CHANGED,
    334         NUM_CONFIG_EVENTS
    335     };
    336 
    337     // audio output descritor used to cache output configurations in client process to avoid frequent calls
    338     // through IAudioFlinger
    339     class OutputDescriptor {
    340     public:
    341         OutputDescriptor()
    342         : samplingRate(0), format(0), channels(0), frameCount(0), latency(0)  {}
    343 
    344         uint32_t samplingRate;
    345         int32_t format;
    346         int32_t channels;
    347         size_t frameCount;
    348         uint32_t latency;
    349     };
    350 
    351     //
    352     // IAudioPolicyService interface (see AudioPolicyInterface for method descriptions)
    353     //
    354     static status_t setDeviceConnectionState(audio_devices device, device_connection_state state, const char *device_address);
    355     static device_connection_state getDeviceConnectionState(audio_devices device, const char *device_address);
    356     static status_t setPhoneState(int state);
    357     static status_t setRingerMode(uint32_t mode, uint32_t mask);
    358     static status_t setForceUse(force_use usage, forced_config config);
    359     static forced_config getForceUse(force_use usage);
    360     static audio_io_handle_t getOutput(stream_type stream,
    361                                         uint32_t samplingRate = 0,
    362                                         uint32_t format = FORMAT_DEFAULT,
    363                                         uint32_t channels = CHANNEL_OUT_STEREO,
    364                                         output_flags flags = OUTPUT_FLAG_INDIRECT);
    365     static status_t startOutput(audio_io_handle_t output,
    366                                 AudioSystem::stream_type stream,
    367                                 int session = 0);
    368     static status_t stopOutput(audio_io_handle_t output,
    369                                AudioSystem::stream_type stream,
    370                                int session = 0);
    371     static void releaseOutput(audio_io_handle_t output);
    372     static audio_io_handle_t getInput(int inputSource,
    373                                     uint32_t samplingRate = 0,
    374                                     uint32_t format = FORMAT_DEFAULT,
    375                                     uint32_t channels = CHANNEL_IN_MONO,
    376                                     audio_in_acoustics acoustics = (audio_in_acoustics)0);
    377     static status_t startInput(audio_io_handle_t input);
    378     static status_t stopInput(audio_io_handle_t input);
    379     static void releaseInput(audio_io_handle_t input);
    380     static status_t initStreamVolume(stream_type stream,
    381                                       int indexMin,
    382                                       int indexMax);
    383     static status_t setStreamVolumeIndex(stream_type stream, int index);
    384     static status_t getStreamVolumeIndex(stream_type stream, int *index);
    385 
    386     static uint32_t getStrategyForStream(stream_type stream);
    387 
    388     static audio_io_handle_t getOutputForEffect(effect_descriptor_t *desc);
    389     static status_t registerEffect(effect_descriptor_t *desc,
    390                                     audio_io_handle_t output,
    391                                     uint32_t strategy,
    392                                     int session,
    393                                     int id);
    394     static status_t unregisterEffect(int id);
    395 
    396     static const sp<IAudioPolicyService>& get_audio_policy_service();
    397 
    398     // ----------------------------------------------------------------------------
    399 
    400     static uint32_t popCount(uint32_t u);
    401     static bool isOutputDevice(audio_devices device);
    402     static bool isInputDevice(audio_devices device);
    403     static bool isA2dpDevice(audio_devices device);
    404     static bool isBluetoothScoDevice(audio_devices device);
    405     static bool isLowVisibility(stream_type stream);
    406     static bool isOutputChannel(uint32_t channel);
    407     static bool isInputChannel(uint32_t channel);
    408     static bool isValidFormat(uint32_t format);
    409     static bool isLinearPCM(uint32_t format);
    410 
    411 private:
    412 
    413     class AudioFlingerClient: public IBinder::DeathRecipient, public BnAudioFlingerClient
    414     {
    415     public:
    416         AudioFlingerClient() {
    417         }
    418 
    419         // DeathRecipient
    420         virtual void binderDied(const wp<IBinder>& who);
    421 
    422         // IAudioFlingerClient
    423 
    424         // indicate a change in the configuration of an output or input: keeps the cached
    425         // values for output/input parameters upto date in client process
    426         virtual void ioConfigChanged(int event, int ioHandle, void *param2);
    427     };
    428 
    429     class AudioPolicyServiceClient: public IBinder::DeathRecipient
    430     {
    431     public:
    432         AudioPolicyServiceClient() {
    433         }
    434 
    435         // DeathRecipient
    436         virtual void binderDied(const wp<IBinder>& who);
    437     };
    438 
    439     static sp<AudioFlingerClient> gAudioFlingerClient;
    440     static sp<AudioPolicyServiceClient> gAudioPolicyServiceClient;
    441     friend class AudioFlingerClient;
    442     friend class AudioPolicyServiceClient;
    443 
    444     static Mutex gLock;
    445     static sp<IAudioFlinger> gAudioFlinger;
    446     static audio_error_callback gAudioErrorCallback;
    447 
    448     static size_t gInBuffSize;
    449     // previous parameters for recording buffer size queries
    450     static uint32_t gPrevInSamplingRate;
    451     static int gPrevInFormat;
    452     static int gPrevInChannelCount;
    453 
    454     static sp<IAudioPolicyService> gAudioPolicyService;
    455 
    456     // mapping between stream types and outputs
    457     static DefaultKeyedVector<int, audio_io_handle_t> gStreamOutputMap;
    458     // list of output descritor containing cached parameters (sampling rate, framecount, channel count...)
    459     static DefaultKeyedVector<audio_io_handle_t, OutputDescriptor *> gOutputs;
    460 };
    461 
    462 class AudioParameter {
    463 
    464 public:
    465     AudioParameter() {}
    466     AudioParameter(const String8& keyValuePairs);
    467     virtual ~AudioParameter();
    468 
    469     // reserved parameter keys for changeing standard parameters with setParameters() function.
    470     // Using these keys is mandatory for AudioFlinger to properly monitor audio output/input
    471     // configuration changes and act accordingly.
    472     //  keyRouting: to change audio routing, value is an int in AudioSystem::audio_devices
    473     //  keySamplingRate: to change sampling rate routing, value is an int
    474     //  keyFormat: to change audio format, value is an int in AudioSystem::audio_format
    475     //  keyChannels: to change audio channel configuration, value is an int in AudioSystem::audio_channels
    476     //  keyFrameCount: to change audio output frame count, value is an int
    477     static const char *keyRouting;
    478     static const char *keySamplingRate;
    479     static const char *keyFormat;
    480     static const char *keyChannels;
    481     static const char *keyFrameCount;
    482 
    483     String8 toString();
    484 
    485     status_t add(const String8& key, const String8& value);
    486     status_t addInt(const String8& key, const int value);
    487     status_t addFloat(const String8& key, const float value);
    488 
    489     status_t remove(const String8& key);
    490 
    491     status_t get(const String8& key, String8& value);
    492     status_t getInt(const String8& key, int& value);
    493     status_t getFloat(const String8& key, float& value);
    494     status_t getAt(size_t index, String8& key, String8& value);
    495 
    496     size_t size() { return mParameters.size(); }
    497 
    498 private:
    499     String8 mKeyValuePairs;
    500     KeyedVector <String8, String8> mParameters;
    501 };
    502 
    503 };  // namespace android
    504 
    505 #endif  /*ANDROID_AUDIOSYSTEM_H_*/
    506