AudioTrack comments

    };

    /* Events used by AudioTrack callback function (audio_track_cblk_t).

     * Keep in sync with frameworks/base/media/java/android/media/AudioTrack.java NATIVE_EVENT_*.

     */

    enum event_type {

        EVENT_MORE_DATA = 0,        // Request to write more data to PCM buffer.

        EVENT_UNDERRUN = 1,         // PCM buffer underrun occured.

        EVENT_UNDERRUN = 1,         // PCM buffer underrun occurred.

        EVENT_LOOP_END = 2,         // Sample loop end was reached; playback restarted from

                                    // loop start if loop count was not 0.

        EVENT_MARKER = 3,           // Playback head is at the specified marker position

     */

                        AudioTrack();

    /* Creates an audio track and registers it with AudioFlinger.

    /* Creates an AudioTrack object and registers it with AudioFlinger.

     * Once created, the track needs to be started before it can be used.

     * Unspecified values are set to the audio hardware's current

     * values.

     *                     16 bits per sample).

     * channelMask:        Channel mask.

     * frameCount:         Minimum size of track PCM buffer in frames. This defines the

     *                     application's contribution to the

     *                     latency of the track. The actual size selected by the AudioTrack could be

     *                     larger if the requested size is not compatible with current audio HAL

     *                     latency.  Zero means to use a default value.

     * flags:              See comments on audio_output_flags_t in <system/audio.h>.

     * cbf:                Callback function. If not null, this function is called periodically

     *                     to request new PCM data.

     *                     to provide new PCM data.

     * user:               Context for use by the callback receiver.

     * notificationFrames: The callback function is called each time notificationFrames PCM

     *                     frames have been consumed from track input buffer.

     *  - INVALID_OPERATION: AudioTrack is already initialized

     *  - BAD_VALUE: invalid parameter (channelMask, format, sampleRate...)

     *  - NO_INIT: audio server or audio hardware not initialized

     * */

     */

            status_t    set(audio_stream_type_t streamType = AUDIO_STREAM_DEFAULT,

                            uint32_t sampleRate = 0,

                            audio_format_t format = AUDIO_FORMAT_DEFAULT,

            status_t    setAuxEffectSendLevel(float level);

            void        getAuxEffectSendLevel(float* level) const;

    /* Set sample rate for this track, mostly used for games' sound effects

    /* Set sample rate for this track in Hz, mostly used for games' sound effects

     */

            status_t    setSampleRate(int sampleRate);

            uint32_t    getSampleRate() const;

     * If the track is stopped, obtainBuffer() returns

     * STOPPED instead of NO_ERROR as long as there are buffers available,

     * at which point NO_MORE_BUFFERS is returned.

     * Buffers will be returned until the pool (buffercount())

     * Buffers will be returned until the pool

     * is exhausted, at which point obtainBuffer() will either block

     * or return WOULD_BLOCK depending on the value of the "blocking"

     * parameter.

    bool                    mActive;                // protected by mLock

    callback_t              mCbf;                   // callback handler for events, or NULL

    void*                   mUserData;

    void*                   mUserData;              // for client callback handler

    // for notification APIs

    uint32_t                mNotificationFramesReq; // requested number of frames between each

                                                    // notification callback

    uint32_t                mNotificationFramesAct; // actual number of frames between each

    sp<IMemory>             mSharedBuffer;

    int                     mLoopCount;

    uint32_t                mRemainingFrames;

    uint32_t                mMarkerPosition;

    uint32_t                mMarkerPosition;        // in frames

    bool                    mMarkerReached;

    uint32_t                mNewPosition;

    uint32_t                mUpdatePeriod;

    uint32_t                mNewPosition;           // in frames

    uint32_t                mUpdatePeriod;          // in frames

    bool                    mFlushed; // FIXME will be made obsolete by making flush() synchronous

    audio_output_flags_t    mFlags;

    int                     mSessionId;