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      1 /*
      2  * libjingle
      3  * Copyright 2004--2010, Google Inc.
      4  *
      5  * Redistribution and use in source and binary forms, with or without
      6  * modification, are permitted provided that the following conditions are met:
      7  *
      8  *  1. Redistributions of source code must retain the above copyright notice,
      9  *     this list of conditions and the following disclaimer.
     10  *  2. Redistributions in binary form must reproduce the above copyright notice,
     11  *     this list of conditions and the following disclaimer in the documentation
     12  *     and/or other materials provided with the distribution.
     13  *  3. The name of the author may not be used to endorse or promote products
     14  *     derived from this software without specific prior written permission.
     15  *
     16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
     17  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
     18  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
     19  * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
     20  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
     21  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
     22  * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
     23  * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
     24  * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
     25  * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     26  */
     27 
     28 #ifndef TALK_SOUND_SOUNDSYSTEMINTERFACE_H_
     29 #define TALK_SOUND_SOUNDSYSTEMINTERFACE_H_
     30 
     31 #include <vector>
     32 
     33 #include "talk/base/constructormagic.h"
     34 
     35 namespace cricket {
     36 
     37 class SoundDeviceLocator;
     38 class SoundInputStreamInterface;
     39 class SoundOutputStreamInterface;
     40 
     41 // Interface for a platform's sound system.
     42 // Implementations must guarantee thread-safety for at least the following use
     43 // cases:
     44 // 1) Concurrent enumeration and opening of devices from different threads.
     45 // 2) Concurrent use of different Sound(Input|Output)StreamInterface
     46 // instances from different threads (but concurrent use of the _same_ one from
     47 // different threads need not be supported).
     48 class SoundSystemInterface {
     49  public:
     50   typedef std::vector<SoundDeviceLocator *> SoundDeviceLocatorList;
     51 
     52   enum SampleFormat {
     53     // Only one supported sample format at this time.
     54     // The values here may be used in lookup tables, so they shouldn't change.
     55     FORMAT_S16LE = 0,
     56   };
     57 
     58   enum Flags {
     59     // Enable reporting the current stream latency in
     60     // Sound(Input|Output)StreamInterface. See those classes for more details.
     61     FLAG_REPORT_LATENCY = (1 << 0),
     62   };
     63 
     64   struct OpenParams {
     65     // Format for the sound stream.
     66     SampleFormat format;
     67     // Sampling frequency in hertz.
     68     unsigned int freq;
     69     // Number of channels in the PCM stream.
     70     unsigned int channels;
     71     // Misc flags. Should be taken from the Flags enum above.
     72     int flags;
     73     // Desired latency, measured as number of bytes of sample data
     74     int latency;
     75   };
     76 
     77   // Special values for the "latency" field of OpenParams.
     78   // Use this one to say you don't care what the latency is. The sound system
     79   // will optimize for other things instead.
     80   static const int kNoLatencyRequirements = -1;
     81   // Use this one to say that you want the sound system to pick an appropriate
     82   // small latency value. The sound system may pick the minimum allowed one, or
     83   // a slightly higher one in the event that the true minimum requires an
     84   // undesirable trade-off.
     85   static const int kLowLatency = 0;
     86 
     87   // Max value for the volume parameters for Sound(Input|Output)StreamInterface.
     88   static const int kMaxVolume = 255;
     89   // Min value for the volume parameters for Sound(Input|Output)StreamInterface.
     90   static const int kMinVolume = 0;
     91 
     92   // Helper for clearing a locator list and deleting the entries.
     93   static void ClearSoundDeviceLocatorList(SoundDeviceLocatorList *devices);
     94 
     95   virtual ~SoundSystemInterface() {}
     96 
     97   virtual bool Init() = 0;
     98   virtual void Terminate() = 0;
     99 
    100   // Enumerates the available devices. (Any pre-existing locators in the lists
    101   // are deleted.)
    102   virtual bool EnumeratePlaybackDevices(SoundDeviceLocatorList *devices) = 0;
    103   virtual bool EnumerateCaptureDevices(SoundDeviceLocatorList *devices) = 0;
    104 
    105   // Gets a special locator for the default device.
    106   virtual bool GetDefaultPlaybackDevice(SoundDeviceLocator **device) = 0;
    107   virtual bool GetDefaultCaptureDevice(SoundDeviceLocator **device) = 0;
    108 
    109   // Opens the given device, or returns NULL on error.
    110   virtual SoundOutputStreamInterface *OpenPlaybackDevice(
    111       const SoundDeviceLocator *device,
    112       const OpenParams &params) = 0;
    113   virtual SoundInputStreamInterface *OpenCaptureDevice(
    114       const SoundDeviceLocator *device,
    115       const OpenParams &params) = 0;
    116 
    117   // A human-readable name for this sound system.
    118   virtual const char *GetName() const = 0;
    119 
    120  protected:
    121   SoundSystemInterface() {}
    122 
    123  private:
    124   DISALLOW_COPY_AND_ASSIGN(SoundSystemInterface);
    125 };
    126 
    127 }  // namespace cricket
    128 
    129 #endif  // TALK_SOUND_SOUNDSYSTEMINTERFACE_H_
    130