[PPAPI] API definition for audio media stream artifacts

ppapi/api/ppb_audio_frame.idl

Index: ppapi/api/ppb_audio_frame.idl
diff --git a/ppapi/api/ppb_audio_frame.idl b/ppapi/api/ppb_audio_frame.idl
new file mode 100644
index 0000000000000000000000000000000000000000..6c30945b49f0498eca1d9b177acf511772e82f26
--- /dev/null
+++ b/ppapi/api/ppb_audio_frame.idl
@@ -0,0 +1,99 @@
+/* Copyright 2014 The Chromium Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+/**
+ * Defines the <code>PPB_AudioFrame</code> interface.
+ */
+label Chrome {
+  [channel=dev] M34 = 0.1
+};
+
+interface PPB_AudioFrame {
+  /**
+   * Determines if a resource is an AudioFrame resource.
+   *
+   * @param[in] resource The <code>PP_Resource</code> to test.
+   *
+   * @return A <code>PP_Bool</code> with <code>PP_TRUE</code> if the given
+   * resource is an AudioFrame resource or <code>PP_FALSE</code> otherwise.
+   */
+  PP_Bool IsAudioFrame([in] PP_Resource resource);
+
+  /**
+   * Gets the timestamp of the audio frame.
+   *
+   * @param[in] frame A <code>PP_Resource</code> corresponding to an audio frame
+   * resource.
+   *
+   * @return A <code>PP_TimeDelta</code> containing the timestamp of the audio
+   * frame. Given in seconds since the start of the containing audio stream.
+   */
+  PP_TimeDelta GetTimestamp([in] PP_Resource frame);
+
+  /**
+   * Sets the timestamp of the audio frame. Given in seconds since the
+   * start of the containing audio stream.
+   *
+   * @param[in] frame A <code>PP_Resource</code> corresponding to an audio frame
+   * resource.
+   * @param[in] timestamp A <code>PP_TimeDelta</code> containing the timestamp
+   * of the audio frame. Given in seconds since the start of the containing
+   * audio stream.
+   */
+  void SetTimestamp([in] PP_Resource frame, [in] PP_TimeDelta timestamp);
+
+  /**
+   * Gets the sample size of the audio frame.
+   *
+   * @param[in] frame A <code>PP_Resource</code> corresponding to an audio frame
+   * resource.
+   *
+   * @return The sample size of the audio frame. It always returns 2 (16 bits)
+   * rignt now.

[dmichael (off chromium), 2014/01/07 22:00:59]

rignt->right

[Peng, 2014/01/07 22:29:27]

Done.

+   */
+  uint32_t GetSampleSize([in] PP_Resource frame);
+  
+  /**
+   * Gets the number of channels in the audio frame.
+   *
+   * @param[in] frame A <code>PP_Resource</code> corresponding to an audio frame
+   * resource.
+   *
+   * @return The number of channles in the audio frame.

[dmichael (off chromium), 2014/01/07 22:00:59]

channles->channels

[Peng, 2014/01/07 22:29:27]

Done.

+   */
+  uint32_t GetNumberOfChannels([in] PP_Resource frame);
+
+  /**
+   * Gets the number of samples in the audio frame.
+   *
+   * @param[in] frame A <code>PP_Resource</code> corresponding to an audio frame
+   * resource.
+   *
+   * @return The number of samples in the audio frame.
+   * For 1 second sample rate 44100 stereo audio frame, the number of samples

[dmichael (off chromium), 2014/01/07 22:00:59]

This is kind of confusingly worded to me. I think you mean something like:
"For example, at a sampling rate of 44,100 Hz in stereo audio, a frame
containing 44100 * 2 samples would have a duration of 1 second."
or something.

We should try to avoid implying that the frame has 1 second of data in it. So
maybe even a more realistic example with shorter time duration would be better.

[Peng, 2014/01/07 22:29:27]

Done.

+   * should be 1 * 44100 * 2.
+   */
+  uint32_t GetNumberOfSamples([in] PP_Resource frame);
+
+  /**
+   * Gets the data buffer for audio frame samples.
+   *
+   * @param[in] frame A <code>PP_Resource</code> corresponding to an audio frame
+   * resource.
+   *
+   * @return A pointer to the beginning of the data buffer.
+   */
+  mem_t GetDataBuffer([in] PP_Resource frame);
+
+  /**
+   * Gets the size of data buffer.

[dmichael (off chromium), 2014/01/07 22:00:59]

of +the+ data buffer +in bytes+.

[Peng, 2014/01/07 22:29:27]

Done.

+   *
+   * @param[in] frame A <code>PP_Resource</code> corresponding to an audio frame
+   * resource.
+   *
+   * @return The size of the data buffer in bytes.
+   */
+  uint32_t GetDataBufferSize([in] PP_Resource frame);
+};