// Copyright 2014 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef PPAPI_CPP_MEDIA_STREAM_AUDIO_TRACK_H_
#define PPAPI_CPP_MEDIA_STREAM_AUDIO_TRACK_H_
#include <stdint.h>
#include <string>
#include "ppapi/c/ppb_media_stream_audio_track.h"
#include "ppapi/cpp/resource.h"
#include "ppapi/cpp/var.h"
/// @file
/// This file defines the <code>MediaStreamAudioTrack</code> interface for an
/// audio source resource, which receives audio buffers from a MediaStream audio
/// track in the browser.
namespace pp {
class AudioBuffer;
class CompletionCallback;
template <typename T> class CompletionCallbackWithOutput;
/// The <code>MediaStreamAudioTrack</code> class contains methods for
/// receiving audio buffers from a MediaStream audio track in the browser.
class MediaStreamAudioTrack : public Resource {
public:
/// Default constructor for creating an is_null()
/// <code>MediaStreamAudioTrack</code> object.
MediaStreamAudioTrack();
/// The copy constructor for <code>MediaStreamAudioTrack</code>.
///
/// @param[in] other A reference to a <code>MediaStreamAudioTrack</code>.
MediaStreamAudioTrack(const MediaStreamAudioTrack& other);
/// Constructs a <code>MediaStreamAudioTrack</code> from
/// a <code>Resource</code>.
///
/// @param[in] resource A <code>PPB_MediaStreamAudioTrack</code> resource.
explicit MediaStreamAudioTrack(const Resource& resource);
/// A constructor used when you have received a <code>PP_Resource</code> as a
/// return value that has had 1 ref added for you.
///
/// @param[in] resource A <code>PPB_MediaStreamAudioTrack</code> resource.
MediaStreamAudioTrack(PassRef, PP_Resource resource);
~MediaStreamAudioTrack();
/// Configures underlying buffer buffers for incoming audio samples.
/// If the application doesn't want to drop samples, then the
/// <code>PP_MEDIASTREAMAUDIOTRACK_ATTRIB_BUFFERS</code> should be
/// chosen such that inter-buffer processing time variability won't overrun
/// all input buffers. If all buffers are filled, then samples will be
/// dropped. The application can detect this by examining the timestamp on
/// returned buffers. If <code>Configure()</code> is not called, default
/// settings will be used. Calls to Configure while the plugin holds
/// buffers will fail.
/// Example usage from plugin code:
/// @code
/// int32_t attribs[] = {
/// PP_MEDIASTREAMAUDIOTRACK_ATTRIB_BUFFERS, 4,
/// PP_MEDIASTREAMAUDIOTRACK_ATTRIB_DURATION, 10,
/// PP_MEDIASTREAMAUDIOTRACK_ATTRIB_NONE};
/// track.Configure(attribs, callback);
/// @endcode
///
/// @param[in] attrib_list A list of attribute name-value pairs in which each
/// attribute is immediately followed by the corresponding desired value.
/// The list is terminated by
/// <code>PP_MEDIASTREAMAUDIOTRACK_AUDIO_NONE</code>.
/// @param[in] callback A <code>CompletionCallback</code> to be called upon
/// completion of <code>Configure()</code>.
///
/// @return An int32_t containing a result code from <code>pp_errors.h</code>.
int32_t Configure(const int32_t attributes[],
const CompletionCallback& callback);
/// Gets attribute value for a given attribute name.
///
/// @param[in] attrib A <code>PP_MediaStreamAudioTrack_Attrib</code> for
/// querying.
/// @param[out] value A int32_t for storing the attribute value.
///
/// @return An int32_t containing a result code from <code>pp_errors.h</code>.
int32_t GetAttrib(PP_MediaStreamAudioTrack_Attrib attrib,
int32_t* value);
/// Returns the track ID of the underlying MediaStream audio track.
std::string GetId() const;
/// Checks whether the underlying MediaStream track has ended.
/// Calls to GetBuffer while the track has ended are safe to make and will
/// complete, but will fail.
bool HasEnded() const;
/// Gets the next audio buffer from the MediaStream track.
/// If internal processing is slower than the incoming buffer rate,
/// new buffers will be dropped from the incoming stream. Once all buffers
/// are full, audio samples will be dropped until <code>RecycleBuffer()</code>
/// is called to free a spot for another buffer.
/// If there are no audio data in the input buffer,
/// <code>PP_OK_COMPLETIONPENDING</code> will be returned immediately and the
/// <code>callback</code> will be called when a new buffer of audio samples
/// is received or some error happens.
///
/// @param[in] callback A <code>CompletionCallbackWithOutput</code> to be
/// called upon completion of <code>GetBuffer()</code>. If success,
/// an AudioBuffer will be passed into the completion callback function.
///
/// @return An int32_t containing a result code from <code>pp_errors.h</code>.
int32_t GetBuffer(
const CompletionCallbackWithOutput<AudioBuffer>& callback);
/// Recycles a buffer returned by <code>GetBuffer()</code>, so the track can
/// reuse the buffer. And the buffer will become invalid. The caller should
/// release all references it holds to <code>buffer</code> and not use it
/// anymore.
///
/// @param[in] buffer A AudioBuffer returned by <code>GetBuffer()</code>.
///
/// @return An int32_t containing a result code from <code>pp_errors.h</code>.
int32_t RecycleBuffer(const AudioBuffer& buffer);
/// Closes the MediaStream audio track, and disconnects it from the audio
/// source.
/// After calling <code>Close()</code>, no new buffers will be received.
void Close();
/// Checks whether a <code>Resource</code> is a MediaStream audio track,
/// to test whether it is appropriate for use with the
/// <code>MediaStreamAudioTrack</code> constructor.
///
/// @param[in] resource A <code>Resource</code> to test.
///
/// @return True if <code>resource</code> is a MediaStream audio track.
static bool IsMediaStreamAudioTrack(const Resource& resource);
};
} // namespace pp
#endif // PPAPI_CPP_MEDIA_STREAM_AUDIO_TRACK_H_
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