ppapi/c/ppb_audio.h

   1 /* Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2  * Use of this source code is governed by a BSD-style license that can be
   3  * found in the LICENSE file.
   4  */
   5
   6 /* From ppb_audio.idl modified Mon Jul  9 12:03:36 2012. */
   7
   8 #ifndef PPAPI_C_PPB_AUDIO_H_
   9 #define PPAPI_C_PPB_AUDIO_H_
  10
  11 #include "ppapi/c/pp_bool.h"
  12 #include "ppapi/c/pp_instance.h"
  13 #include "ppapi/c/pp_macros.h"
  14 #include "ppapi/c/pp_resource.h"
  15 #include "ppapi/c/pp_stdint.h"
  16
  17 #define PPB_AUDIO_INTERFACE_1_0 "PPB_Audio;1.0"
  18 #define PPB_AUDIO_INTERFACE PPB_AUDIO_INTERFACE_1_0
  19
  20 /**
  21  * @file
  22  * This file defines the <code>PPB_Audio</code> interface, which provides
  23  * realtime stereo audio streaming capabilities.
  24  */
  25
  26
  27 /**
  28  * @addtogroup Typedefs
  29  * @{
  30  */
  31 /**
  32  * <code>PPB_Audio_Callback</code> defines the type of an audio callback
  33  * function used to fill the audio buffer with data. Please see the
  34  * Create() function in the <code>PPB_Audio</code> interface for
  35  * more details on this callback.
  36  */
  37 typedef void (*PPB_Audio_Callback)(void* sample_buffer,
  38                                    uint32_t buffer_size_in_bytes,
  39                                    void* user_data);
  40 /**
  41  * @}
  42  */
  43
  44 /**
  45  * @addtogroup Interfaces
  46  * @{
  47  */
  48 /**
  49  * The <code>PPB_Audio</code> interface contains pointers to several functions
  50  * for handling audio resources. Refer to the
  51  * <a href="/native-client/{{pepperversion}}/devguide/coding/audio">Audio</a>
  52  * chapter in the Developer's Guide for information on using this interface.
  53  * Please see descriptions for each <code>PPB_Audio</code> and
  54  * <code>PPB_AudioConfig</code> function for more details. A C example using
  55  * <code>PPB_Audio</code> and <code>PPB_AudioConfig</code> follows.
  56  *
  57  * <strong>Example: </strong>
  58  *
  59  * @code
  60  * void audio_callback(void* sample_buffer,
  61  *                     uint32_t buffer_size_in_bytes,
  62  *                     void* user_data) {
  63  *   ... quickly fill in the buffer with samples and return to caller ...
  64  *  }
  65  *
  66  * ...Assume the application has cached the audio configuration interface in
  67  * audio_config_interface and the audio interface in
  68  * audio_interface...
  69  *
  70  * uint32_t count = audio_config_interface->RecommendSampleFrameCount(
  71  *     PP_AUDIOSAMPLERATE_44100, 4096);
  72  * PP_Resource pp_audio_config = audio_config_interface->CreateStereo16Bit(
  73  *     pp_instance, PP_AUDIOSAMPLERATE_44100, count);
  74  * PP_Resource pp_audio = audio_interface->Create(pp_instance, pp_audio_config,
  75  *     audio_callback, NULL);
  76  * audio_interface->StartPlayback(pp_audio);
  77  *
  78  * ...audio_callback() will now be periodically invoked on a separate thread...
  79  * @endcode
  80  */
  81 struct PPB_Audio_1_0 {
  82   /**
  83    * Create() creates an audio resource. No sound will be heard until
  84    * StartPlayback() is called. The callback is called with the buffer address
  85    * and given user data whenever the buffer needs to be filled. From within the
  86    * callback, you should not call <code>PPB_Audio</code> functions. The
  87    * callback will be called on a different thread than the one which created
  88    * the interface. For performance-critical applications (i.e. low-latency
  89    * audio), the callback should avoid blocking or calling functions that can
  90    * obtain locks, such as malloc. The layout and the size of the buffer passed
  91    * to the audio callback will be determined by the device configuration and is
  92    * specified in the <code>AudioConfig</code> documentation.
  93    *
  94    * @param[in] instance A <code>PP_Instance</code> identifying one instance
  95    * of a module.
  96    * @param[in] config A <code>PP_Resource</code> corresponding to an audio
  97    * config resource.
  98    * @param[in] audio_callback A <code>PPB_Audio_Callback</code> callback
  99    * function that the browser calls when it needs more samples to play.
 100    * @param[in] user_data A pointer to user data used in the callback function.
 101    *
 102    * @return A <code>PP_Resource</code> containing the audio resource if
 103    * successful or 0 if the configuration cannot be honored or the callback is
 104    * null.
 105    */
 106   PP_Resource (*Create)(PP_Instance instance,
 107                         PP_Resource config,
 108                         PPB_Audio_Callback audio_callback,
 109                         void* user_data);
 110   /**
 111    * IsAudio() determines if the provided resource is an audio resource.
 112    *
 113    * @param[in] resource A <code>PP_Resource</code> corresponding to a generic
 114    * resource.
 115    *
 116    * @return A <code>PP_Bool</code> containing containing <code>PP_TRUE</code>
 117    * if the given resource is an Audio resource, otherwise
 118    * <code>PP_FALSE</code>.
 119    */
 120   PP_Bool (*IsAudio)(PP_Resource resource);
 121   /**
 122    * GetCurrrentConfig() returns an audio config resource for the given audio
 123    * resource.
 124    *
 125    * @param[in] config A <code>PP_Resource</code> corresponding to an audio
 126    * resource.
 127    *
 128    * @return A <code>PP_Resource</code> containing the audio config resource if
 129    * successful.
 130    */
 131   PP_Resource (*GetCurrentConfig)(PP_Resource audio);
 132   /**
 133    * StartPlayback() starts the playback of the audio resource and begins
 134    * periodically calling the callback.
 135    *
 136    * @param[in] config A <code>PP_Resource</code> corresponding to an audio
 137    * resource.
 138    *
 139    * @return A <code>PP_Bool</code> containing <code>PP_TRUE</code> if
 140    * successful, otherwise <code>PP_FALSE</code>. Also returns
 141    * <code>PP_TRUE</code> (and be a no-op) if called while playback is already
 142    * in progress.
 143    */
 144   PP_Bool (*StartPlayback)(PP_Resource audio);
 145   /**
 146    * StopPlayback() stops the playback of the audio resource.
 147    *
 148    * @param[in] config A <code>PP_Resource</code> corresponding to an audio
 149    * resource.
 150    *
 151    * @return A <code>PP_Bool</code> containing <code>PP_TRUE</code> if
 152    * successful, otherwise <code>PP_FALSE</code>. Also returns
 153    * <code>PP_TRUE</code> (and is a no-op) if called while playback is already
 154    * stopped. If a callback is in progress, StopPlayback() will block until the
 155    * callback completes.
 156    */
 157   PP_Bool (*StopPlayback)(PP_Resource audio);
 158 };
 159
 160 typedef struct PPB_Audio_1_0 PPB_Audio;
 161 /**
 162  * @}
 163  */
 164
 165 #endif  /* PPAPI_C_PPB_AUDIO_H_ */
 166