ppapi/api/ppb_audio.idl

   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 /**
   7  * This file defines the <code>PPB_Audio</code> interface, which provides
   8  * realtime stereo audio streaming capabilities.
   9  */
  10
  11 [generate_thunk]
  12
  13 label Chrome {
  14   M14 = 1.0
  15 };
  16
  17 /**
  18  * <code>PPB_Audio_Callback</code> defines the type of an audio callback
  19  * function used to fill the audio buffer with data. Please see the
  20  * Create() function in the <code>PPB_Audio</code> interface for
  21  * more details on this callback.
  22  */
  23 typedef void PPB_Audio_Callback([out] mem_t sample_buffer,
  24                                 [in] uint32_t buffer_size_in_bytes,
  25                                 [inout] mem_t user_data);
  26
  27 /**
  28  * The <code>PPB_Audio</code> interface contains pointers to several functions
  29  * for handling audio resources. Refer to the
  30  * <a href="/native-client/{{pepperversion}}/devguide/coding/audio">Audio</a>
  31  * chapter in the Developer's Guide for information on using this interface.
  32  * Please see descriptions for each <code>PPB_Audio</code> and
  33  * <code>PPB_AudioConfig</code> function for more details. A C example using
  34  * <code>PPB_Audio</code> and <code>PPB_AudioConfig</code> follows.
  35  *
  36  * <strong>Example: </strong>
  37  *
  38  * @code
  39  * void audio_callback(void* sample_buffer,
  40  *                     uint32_t buffer_size_in_bytes,
  41  *                     void* user_data) {
  42  *   ... quickly fill in the buffer with samples and return to caller ...
  43  *  }
  44  *
  45  * ...Assume the application has cached the audio configuration interface in
  46  * audio_config_interface and the audio interface in
  47  * audio_interface...
  48  *
  49  * uint32_t count = audio_config_interface->RecommendSampleFrameCount(
  50  *     PP_AUDIOSAMPLERATE_44100, 4096);
  51  * PP_Resource pp_audio_config = audio_config_interface->CreateStereo16Bit(
  52  *     pp_instance, PP_AUDIOSAMPLERATE_44100, count);
  53  * PP_Resource pp_audio = audio_interface->Create(pp_instance, pp_audio_config,
  54  *     audio_callback, NULL);
  55  * audio_interface->StartPlayback(pp_audio);
  56  *
  57  * ...audio_callback() will now be periodically invoked on a separate thread...
  58  * @endcode
  59  */
  60 interface PPB_Audio {
  61  /**
  62   * Create() creates an audio resource. No sound will be heard until
  63   * StartPlayback() is called. The callback is called with the buffer address
  64   * and given user data whenever the buffer needs to be filled. From within the
  65   * callback, you should not call <code>PPB_Audio</code> functions. The
  66   * callback will be called on a different thread than the one which created
  67   * the interface. For performance-critical applications (i.e. low-latency
  68   * audio), the callback should avoid blocking or calling functions that can
  69   * obtain locks, such as malloc. The layout and the size of the buffer passed
  70   * to the audio callback will be determined by the device configuration and is
  71   * specified in the <code>AudioConfig</code> documentation.
  72   *
  73   * @param[in] instance A <code>PP_Instance</code> identifying one instance
  74   * of a module.
  75   * @param[in] config A <code>PP_Resource</code> corresponding to an audio
  76   * config resource.
  77   * @param[in] audio_callback A <code>PPB_Audio_Callback</code> callback
  78   * function that the browser calls when it needs more samples to play.
  79   * @param[in] user_data A pointer to user data used in the callback function.
  80   *
  81   * @return A <code>PP_Resource</code> containing the audio resource if
  82   * successful or 0 if the configuration cannot be honored or the callback is
  83   * null.
  84   */
  85   PP_Resource Create(
  86       [in] PP_Instance instance,
  87       [in] PP_Resource config,
  88       [in] PPB_Audio_Callback audio_callback,
  89       [inout] mem_t user_data);
  90
  91   /**
  92    * IsAudio() determines if the provided resource is an audio resource.
  93    *
  94    * @param[in] resource A <code>PP_Resource</code> corresponding to a generic
  95    * resource.
  96    *
  97    * @return A <code>PP_Bool</code> containing containing <code>PP_TRUE</code>
  98    * if the given resource is an Audio resource, otherwise
  99    * <code>PP_FALSE</code>.
 100    */
 101   PP_Bool IsAudio(
 102       [in] PP_Resource resource);
 103
 104   /**
 105    * GetCurrrentConfig() returns an audio config resource for the given audio
 106    * resource.
 107    *
 108    * @param[in] config A <code>PP_Resource</code> corresponding to an audio
 109    * resource.
 110    *
 111    * @return A <code>PP_Resource</code> containing the audio config resource if
 112    * successful.
 113    */
 114   PP_Resource GetCurrentConfig(
 115       [in] PP_Resource audio);
 116
 117   /**
 118    * StartPlayback() starts the playback of the audio resource and begins
 119   * periodically calling the callback.
 120    *
 121    * @param[in] config A <code>PP_Resource</code> corresponding to an audio
 122    * resource.
 123    *
 124    * @return A <code>PP_Bool</code> containing <code>PP_TRUE</code> if
 125    * successful, otherwise <code>PP_FALSE</code>. Also returns
 126    * <code>PP_TRUE</code> (and be a no-op) if called while playback is already
 127    * in progress.
 128    */
 129   PP_Bool StartPlayback(
 130       [in] PP_Resource audio);
 131
 132   /**
 133    * StopPlayback() stops the playback of the audio resource.
 134    *
 135    * @param[in] config A <code>PP_Resource</code> corresponding to an audio
 136    * resource.
 137    *
 138    * @return A <code>PP_Bool</code> containing <code>PP_TRUE</code> if
 139    * successful, otherwise <code>PP_FALSE</code>. Also returns
 140    * <code>PP_TRUE</code> (and is a no-op) if called while playback is already
 141    * stopped. If a callback is in progress, StopPlayback() will block until the
 142    * callback completes.
 143    */
 144   PP_Bool StopPlayback(
 145       [in] PP_Resource audio);
 146 };
 147