// 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_VIDEO_TRACK_H_
#define PPAPI_CPP_MEDIA_STREAM_VIDEO_TRACK_H_
#include <stdint.h>
#include <string>
#include "ppapi/c/ppb_media_stream_video_track.h"
#include "ppapi/cpp/resource.h"
#include "ppapi/cpp/var.h"
/// @file
/// This file defines the <code>MediaStreamVideoTrack</code> interface for a
/// video source resource, which receives video frames from a MediaStream video
/// track in the browser.
namespace pp {
class VideoFrame;
class CompletionCallback;
template <typename T> class CompletionCallbackWithOutput;
/// The <code>MediaStreamVideoTrack</code> class contains methods for
/// receiving video frames from a MediaStream video track in the browser.
class MediaStreamVideoTrack : public Resource {
public:
/// Default constructor for creating an is_null()
/// <code>MediaStreamVideoTrack</code> object.
MediaStreamVideoTrack();
/// The copy constructor for <code>MediaStreamVideoTrack</code>.
///
/// @param[in] other A reference to a <code>MediaStreamVideoTrack</code>.
MediaStreamVideoTrack(const MediaStreamVideoTrack& other);
/// Constructs a <code>MediaStreamVideoTrack</code> from
/// a <code>Resource</code>.
///
/// @param[in] resource A <code>PPB_MediaStreamVideoTrack</code> resource.
explicit MediaStreamVideoTrack(const Resource& resource);
/// Constructs a <code>MediaStreamVideoTrack</code> that outputs given frames
/// to a new video track, which will be consumed by Javascript.
explicit MediaStreamVideoTrack(const InstanceHandle& instance);
/// 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_MediaStreamVideoTrack</code> resource.
MediaStreamVideoTrack(PassRef, PP_Resource resource);
~MediaStreamVideoTrack();
/// Configures underlying frame buffers for incoming frames.
/// If the application doesn't want to drop frames, then the
/// <code>PP_MEDIASTREAMVIDEOTRACK_ATTRIB_BUFFERED_FRAMES</code> should be
/// chosen such that inter-frame processing time variability won't overrun the
/// input buffer. If the buffer is overfilled, then frames will be dropped.
/// The application can detect this by examining the timestamp on returned
/// frames. If some attributes are not specified, default values will be used
/// for those unspecified attributes. If <code>Configure()</code> is not
/// called, default settings will be used.
/// Example usage from plugin code:
/// @code
/// int32_t attribs[] = {
/// PP_MEDIASTREAMVIDEOTRACK_ATTRIB_BUFFERED_FRAMES, 4,
/// PP_MEDIASTREAMVIDEOTRACK_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_MEDIASTREAMVIDEOTRACK_ATTRIB_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>.
/// Returns <code>PP_ERROR_INPROGRESS</code> if there is a pending call of
/// <code>Configure()</code> or <code>GetFrame()</code>, or the plugin
/// holds some frames which are not recycled with <code>RecycleFrame()</code>.
/// If an error is returned, all attributes and the underlying buffer will not
/// be changed.
int32_t Configure(const int32_t attributes[],
const CompletionCallback& callback);
/// Gets attribute value for a given attribute name.
///
/// @param[in] attrib A <code>PP_MediaStreamVideoTrack_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_MediaStreamVideoTrack_Attrib attrib,
int32_t* value);
/// Returns the track ID of the underlying MediaStream video track.
std::string GetId() const;
/// Checks whether the underlying MediaStream track has ended.
/// Calls to GetFrame while the track has ended are safe to make and will
/// complete, but will fail.
bool HasEnded() const;
/// Gets the next video frame from the MediaStream track.
/// If internal processing is slower than the incoming frame rate, new frames
/// will be dropped from the incoming stream. Once the input buffer is full,
/// frames will be dropped until <code>RecycleFrame()</code> is called to free
/// a spot for another frame to be buffered.
/// If there are no frames in the input buffer,
/// <code>PP_OK_COMPLETIONPENDING</code> will be returned immediately and the
/// <code>callback</code> will be called when a new frame is received or some
/// error happens.
///
/// @param[in] callback A <code>CompletionCallbackWithOutput</code> to be
/// called upon completion of <code>GetFrame()</code>. If success,
/// a VideoFrame will be passed into the completion callback function.
///
/// @return An int32_t containing a result code from <code>pp_errors.h</code>.
/// Returns PP_ERROR_NOMEMORY if <code>max_buffered_frames</code> frames
/// buffer was not allocated successfully.
int32_t GetFrame(
const CompletionCallbackWithOutput<VideoFrame>& callback);
/// Recycles a frame returned by <code>GetFrame()</code>, so the track can
/// reuse the underlying buffer of this frame. And the frame will become
/// invalid. The caller should release all references it holds to
/// <code>frame</code> and not use it anymore.
///
/// @param[in] frame A VideoFrame returned by <code>GetFrame()</code>.
///
/// @return An int32_t containing a result code from <code>pp_errors.h</code>.
int32_t RecycleFrame(const VideoFrame& frame);
/// Closes the MediaStream video track, and disconnects it from video source.
/// After calling <code>Close()</code>, no new frames will be received.
void Close();
// Gets a free frame for output. The frame is allocated by
// <code>Configure()</code>. The caller should fill it with frame data, and
// then use |PutFrame()| to send the frame back.
int32_t GetEmptyFrame(
const CompletionCallbackWithOutput<VideoFrame>& callback);
// Sends a frame returned by |GetEmptyFrame()| to the output track.
// After this function, the |frame| should not be used anymore and the
// caller should release the reference that it holds.
int32_t PutFrame(const VideoFrame& frame);
/// Checks whether a <code>Resource</code> is a MediaStream video track,
/// to test whether it is appropriate for use with the
/// <code>MediaStreamVideoTrack</code> constructor.
///
/// @param[in] resource A <code>Resource</code> to test.
///
/// @return True if <code>resource</code> is a MediaStream video track.
static bool IsMediaStreamVideoTrack(const Resource& resource);
};
} // namespace pp
#endif // PPAPI_CPP_MEDIA_STREAM_VIDEO_TRACK_H_
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