1/* Copyright 2014 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 * Defines the <code>PPB_MediaStreamAudioTrack</code> interface. Used for
8 * receiving audio samples from a MediaStream audio track in the browser.
9 */
10
11[generate_thunk]
12
13label Chrome {
14  [channel=dev] M34 = 0.1,
15  M35 = 0.1
16};
17
18/**
19 * This enumeration contains audio track attributes which are used by
20 * <code>Configure()</code>.
21 */
22enum PP_MediaStreamAudioTrack_Attrib {
23  /**
24   * Attribute list terminator.
25   */
26  PP_MEDIASTREAMAUDIOTRACK_ATTRIB_NONE = 0,
27
28  /**
29   * The maximum number of buffers to hold audio samples.
30   * Note: this is only used as advisory; the browser may allocate more or fewer
31   * based on available resources. How many buffers depends on usage -
32   * request at least 2 to make sure latency doesn't cause lost samples. If
33   * the plugin expects to hold on to more than one buffer at a time (e.g. to do
34   * multi-buffer processing), it should request that many more.
35   */
36  PP_MEDIASTREAMAUDIOTRACK_ATTRIB_BUFFERS = 1,
37
38  /**
39   * The sample rate of audio data in buffers. The attribute value is a
40   * <code>PP_AudioBuffer_SampleRate</code>.
41   */
42  PP_MEDIASTREAMAUDIOTRACK_ATTRIB_SAMPLE_RATE = 2,
43
44  /**
45   * The sample size of audio data in buffers in bytes. The attribute value is a
46   * <code>PP_AudioBuffer_SampleSize</code>.
47   */
48  PP_MEDIASTREAMAUDIOTRACK_ATTRIB_SAMPLE_SIZE = 3,
49
50  /**
51   * The number of channels in audio buffers.
52   *
53   * Supported values: 1, 2
54   */
55  PP_MEDIASTREAMAUDIOTRACK_ATTRIB_CHANNELS = 4,
56
57  /**
58   * The duration of an audio buffer in milliseconds.
59   *
60   * Valid range: 10 to 10000
61   */
62  PP_MEDIASTREAMAUDIOTRACK_ATTRIB_DURATION = 5
63};
64
65[version=0.1]
66interface PPB_MediaStreamAudioTrack {
67  /**
68   * Determines if a resource is a MediaStream audio track resource.
69   *
70   * @param[in] resource The <code>PP_Resource</code> to test.
71   *
72   * @return A <code>PP_Bool</code> with <code>PP_TRUE</code> if the given
73   * resource is a Mediastream audio track resource or <code>PP_FALSE</code>
74   * otherwise.
75   */
76  PP_Bool IsMediaStreamAudioTrack([in] PP_Resource resource);
77
78  /**
79   * Configures underlying buffers for incoming audio samples.
80   * If the application doesn't want to drop samples, then the
81   * <code>PP_MEDIASTREAMAUDIOTRACK_ATTRIB_BUFFERS</code> should be
82   * chosen such that inter-buffer processing time variability won't overrun all
83   * the input buffers. If all buffers are filled, then samples will be
84   * dropped. The application can detect this by examining the timestamp on
85   * returned buffers. If <code>Configure()</code> is not called, default
86   * settings will be used. Calls to Configure while the plugin holds
87   * buffers will fail.
88   * Example usage from plugin code:
89   * @code
90   * int32_t attribs[] = {
91   *     PP_MEDIASTREAMAUDIOTRACK_ATTRIB_BUFFERS, 4,
92   *     PP_MEDIASTREAMAUDIOTRACK_ATTRIB_DURATION, 10,
93   *     PP_MEDIASTREAMAUDIOTRACK_ATTRIB_NONE};
94   * track_if->Configure(track, attribs, callback);
95   * @endcode
96   *
97   * @param[in] audio_track A <code>PP_Resource</code> corresponding to an audio
98   * resource.
99   * @param[in] attrib_list A list of attribute name-value pairs in which each
100   * attribute is immediately followed by the corresponding desired value.
101   * The list is terminated by
102   * <code>PP_MEDIASTREAMAUDIOTRACK_ATTRIB_NONE</code>.
103   * @param[in] callback A <code>PP_CompletionCallback</code> to be called upon
104   * completion of <code>Configure()</code>.
105   *
106   * @return An int32_t containing a result code from <code>pp_errors.h</code>.
107   */
108  int32_t Configure([in] PP_Resource audio_track,
109                    [in] int32_t[] attrib_list,
110                    [in] PP_CompletionCallback callback);
111
112  /**
113   * Gets attribute value for a given attribute name.
114   *
115   * @param[in] audio_track A <code>PP_Resource</code> corresponding to an audio
116   * resource.
117   * @param[in] attrib A <code>PP_MediaStreamAudioTrack_Attrib</code> for
118   * querying.
119   * @param[out] value A int32_t for storing the attribute value on success.
120   * Otherwise, the value will not be changed.
121   *
122   * @return An int32_t containing a result code from <code>pp_errors.h</code>.
123   */
124  int32_t GetAttrib([in] PP_Resource audio_track,
125                    [in] PP_MediaStreamAudioTrack_Attrib attrib,
126                    [out] int32_t value);
127
128  /**
129   * Returns the track ID of the underlying MediaStream audio track.
130   *
131   * @param[in] audio_track The <code>PP_Resource</code> to check.
132   *
133   * @return A <code>PP_Var</code> containing the MediaStream track ID as
134   * a string.
135   */
136  PP_Var GetId([in] PP_Resource audio_track);
137
138  /**
139   * Checks whether the underlying MediaStream track has ended.
140   * Calls to GetBuffer while the track has ended are safe to make and will
141   * complete, but will fail.
142   *
143   * @param[in] audio_track The <code>PP_Resource</code> to check.
144   *
145   * @return A <code>PP_Bool</code> with <code>PP_TRUE</code> if the given
146   * MediaStream track has ended or <code>PP_FALSE</code> otherwise.
147   */
148  [on_failure=PP_TRUE]
149  PP_Bool HasEnded([in] PP_Resource audio_track);
150
151  /**
152   * Gets the next audio buffer from the MediaStream track.
153   * If internal processing is slower than the incoming buffer rate, new buffers
154   * will be dropped from the incoming stream. Once all buffers are full,
155   * audio samples will be dropped until <code>RecycleBuffer()</code> is called
156   * to free a slot for another buffer.
157   * If there are no audio data in the input buffer,
158   * <code>PP_OK_COMPLETIONPENDING</code> will be returned immediately and the
159   * <code>callback</code> will be called, when a new buffer of audio samples
160   * is received or an error happens.
161   *
162   * @param[in] audio_track A <code>PP_Resource</code> corresponding to an audio
163   * resource.
164   * @param[out] buffer A <code>PP_Resource</code> corresponding to
165   * an AudioBuffer resource.
166   * @param[in] callback A <code>PP_CompletionCallback</code> to be called upon
167   * completion of GetBuffer().
168   *
169   * @return An int32_t containing a result code from <code>pp_errors.h</code>.
170   */
171  int32_t GetBuffer([in] PP_Resource audio_track,
172                    [out] PP_Resource buffer,
173                    [in] PP_CompletionCallback callback);
174
175  /**
176   * Recycles a buffer returned by <code>GetBuffer()</code>, so the track can
177   * reuse the buffer. And the buffer will become invalid. The caller should
178   * release all references it holds to <code>buffer</code> and not use it
179   * anymore.
180   *
181   * @param[in] audio_track A <code>PP_Resource</code> corresponding to an audio
182   * resource.
183   * @param[in] buffer A <code>PP_Resource</code> corresponding to
184   * an AudioBuffer resource returned by <code>GetBuffer()</code>.
185   *
186   * @return An int32_t containing a result code from <code>pp_errors.h</code>.
187   */
188  int32_t RecycleBuffer([in] PP_Resource audio_track,
189                        [in] PP_Resource buffer);
190
191  /**
192   * Closes the MediaStream audio track and disconnects it from the audio
193   * source. After calling <code>Close()</code>, no new buffers will be
194   * received.
195   *
196   * @param[in] audio_track A <code>PP_Resource</code> corresponding to a
197   * MediaStream audio track resource.
198   */
199  void Close([in] PP_Resource audio_track);
200};
201
202