ppapi/cpp/video_encoder.h

   1 // Copyright 2015 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 #ifndef PPAPI_CPP_VIDEO_ENCODER_H_
   6 #define PPAPI_CPP_VIDEO_ENCODER_H_
   7
   8 #include "ppapi/c/pp_codecs.h"
   9 #include "ppapi/c/pp_size.h"
  10 #include "ppapi/cpp/completion_callback.h"
  11 #include "ppapi/cpp/resource.h"
  12 #include "ppapi/cpp/size.h"
  13 #include "ppapi/cpp/video_frame.h"
  14
  15 /// @file
  16 /// This file defines the API to create and use a VideoEncoder resource.
  17
  18 namespace pp {
  19
  20 class InstanceHandle;
  21
  22 /// Video encoder interface.
  23 ///
  24 /// Typical usage:
  25 /// - Call Create() to create a new video encoder resource.
  26 /// - Call GetSupportedFormats() to determine which codecs and profiles are
  27 ///   available.
  28 /// - Call Initialize() to initialize the encoder for a supported profile.
  29 /// - Call GetVideoFrame() to get a blank frame and fill it in, or get a video
  30 ///   frame from another resource, e.g. <code>PPB_MediaStreamVideoTrack</code>.
  31 /// - Call Encode() to push the video frame to the encoder. If an external frame
  32 ///   is pushed, wait for completion to recycle the frame.
  33 /// - Call GetBitstreamBuffer() continuously (waiting for each previous call to
  34 ///   complete) to pull encoded pictures from the encoder.
  35 /// - Call RecycleBitstreamBuffer() after consuming the data in the bitstream
  36 ///   buffer.
  37 /// - To destroy the encoder, the plugin should release all of its references to
  38 ///   it. Any pending callbacks will abort before the encoder is destroyed.
  39 ///
  40 /// Available video codecs vary by platform.
  41 /// All: vp8 (software).
  42 /// ChromeOS, depending on your device: h264 (hardware), vp8 (hardware)
  43 class VideoEncoder : public Resource {
  44  public:
  45   /// Default constructor for creating an is_null() <code>VideoEncoder</code>
  46   /// object.
  47   VideoEncoder();
  48
  49   /// A constructor used to create a <code>VideoEncoder</code> and associate it
  50   /// with the provided <code>Instance</code>.
  51   /// @param[in] instance The instance with which this resource will be
  52   /// associated.
  53   explicit VideoEncoder(const InstanceHandle& instance);
  54
  55   /// The copy constructor for <code>VideoEncoder</code>.
  56   /// @param[in] other A reference to a <code>VideoEncoder</code>.
  57   VideoEncoder(const VideoEncoder& other);
  58
  59   /// Gets an array of supported video encoder profiles.
  60   /// These can be used to choose a profile before calling Initialize().
  61   ///
  62   /// @param[in] callback A <code>CompletionCallbackWithOutput</code> to be
  63   /// called upon completion with the PP_VideoProfileDescription structs.
  64   ///
  65   /// @return If >= 0, the number of supported profiles returned, otherwise an
  66   /// error code from <code>pp_errors.h</code>.
  67   int32_t GetSupportedProfiles(const CompletionCallbackWithOutput<
  68       std::vector<PP_VideoProfileDescription> >& cc);
  69
  70   /// Initializes a video encoder resource. This should be called after
  71   /// GetSupportedProfiles() and before any functions below.
  72   ///
  73   /// @param[in] input_format The <code>PP_VideoFrame_Format</code> of the
  74   /// frames which will be encoded.
  75   /// @param[in] input_visible_size A <code>Size</code> specifying the
  76   /// dimensions of the visible part of the input frames.
  77   /// @param[in] output_profile A <code>PP_VideoProfile</code> specifying the
  78   /// codec profile of the encoded output stream.
  79   /// @param[in] acceleration A <code>PP_HardwareAcceleration</code> specifying
  80   /// whether to use a hardware accelerated or a software implementation.
  81   /// @param[in] callback A <code>CompletionCallback</code> to be called upon
  82   /// completion.
  83   ///
  84   /// @return An int32_t containing an error code from <code>pp_errors.h</code>.
  85   /// Returns PP_ERROR_NOTSUPPORTED if video encoding is not available, or the
  86   /// requested codec profile is not supported.
  87   /// Returns PP_ERROR_NOMEMORY if frame and bitstream buffers can't be created.
  88   int32_t Initialize(const PP_VideoFrame_Format& input_format,
  89                      const Size& input_visible_size,
  90                      const PP_VideoProfile& output_profile,
  91                      const uint32_t initial_bitrate,
  92                      PP_HardwareAcceleration acceleration,
  93                      const CompletionCallback& cc);
  94
  95   /// Gets the number of input video frames that the encoder may hold while
  96   /// encoding. If the plugin is providing the video frames, it should have at
  97   /// least this many available.
  98   ///
  99   /// @return An int32_t containing the number of frames required, or an error
 100   /// code from <code>pp_errors.h</code>.
 101   /// Returns PP_ERROR_FAILED if Initialize() has not successfully completed.
 102   int32_t GetFramesRequired();
 103
 104   /// Gets the coded size of the video frames required by the encoder. Coded
 105   /// size is the logical size of the input frames, in pixels.  The encoder may
 106   /// have hardware alignment requirements that make this different from
 107   /// |input_visible_size|, as requested in the call to Initialize().
 108   ///
 109   /// @param[in] coded_size A <code>Size</code> to hold the coded size.
 110   ///
 111   /// @return An int32_t containing a result code from <code>pp_errors.h</code>.
 112   /// Returns PP_ERROR_FAILED if Initialize() has not successfully completed.
 113   int32_t GetFrameCodedSize(Size* coded_size);
 114
 115   /// Gets a blank video frame which can be filled with video data and passed
 116   /// to the encoder.
 117   ///
 118   /// @param[in] callback A <code>CompletionCallbackWithOutput</code> to be
 119   /// called upon completion with the blank <code>VideoFrame</code> resource.
 120   ///
 121   /// @return An int32_t containing an error code from <code>pp_errors.h</code>.
 122   int32_t GetVideoFrame(const CompletionCallbackWithOutput<VideoFrame>& cc);
 123
 124   /// Encodes a video frame.
 125   ///
 126   /// @param[in] video_frame The <code>VideoFrame</code> to be encoded.
 127   /// @param[in] force_keyframe A <code>PP_Bool> specifying whether the encoder
 128   /// should emit a key frame for this video frame.
 129   /// @param[in] callback A <code>CompletionCallback</code> to be called upon
 130   /// completion. Plugins that pass <code>VideoFrame</code> resources owned
 131   /// by other resources should wait for completion before reusing them.
 132   ///
 133   /// @return An int32_t containing an error code from <code>pp_errors.h</code>.
 134   /// Returns PP_ERROR_FAILED if Initialize() has not successfully completed.
 135   int32_t Encode(const VideoFrame& video_frame,
 136                  bool force_keyframe,
 137                  const CompletionCallback& cc);
 138
 139   /// Gets the next encoded bitstream buffer from the encoder.
 140   ///
 141   /// @param[out] bitstream_buffer A <code>PP_BitstreamBuffer</code> containing
 142   /// encoded video data.
 143   /// @param[in] callback A <code>CompletionCallbackWithOutput</code> to be
 144   /// called upon completion with the next bitstream buffer. The plugin can call
 145   /// GetBitstreamBuffer from the callback in order to continuously "pull"
 146   /// bitstream buffers from the encoder.
 147   ///
 148   /// @return An int32_t containing an error code from <code>pp_errors.h</code>.
 149   /// Returns PP_ERROR_FAILED if Initialize() has not successfully completed.
 150   /// Returns PP_ERROR_INPROGRESS if a prior call to GetBitstreamBuffer() has
 151   /// not completed.
 152   int32_t GetBitstreamBuffer(
 153       const CompletionCallbackWithOutput<PP_BitstreamBuffer>& cc);
 154
 155   /// Recycles a bitstream buffer back to the encoder.
 156   ///
 157   /// @param[in] bitstream_buffer A <code>PP_BitstreamBuffer</code> that is no
 158   /// longer needed by the plugin.
 159   void RecycleBitstreamBuffer(const PP_BitstreamBuffer& bitstream_buffer);
 160
 161   /// Requests a change to encoding parameters. This is only a request,
 162   /// fulfilled on a best-effort basis.
 163   ///
 164   /// @param[in] bitrate The requested new bitrate, in bits per second.
 165   /// @param[in] framerate The requested new framerate, in frames per second.
 166   void RequestEncodingParametersChange(uint32_t bitrate, uint32_t framerate);
 167
 168   /// Closes the video encoder, and cancels any pending encodes. Any pending
 169   /// callbacks will still run, reporting <code>PP_ERROR_ABORTED</code> . It is
 170   /// not valid to call any encoder functions after a call to this method.
 171   /// <strong>Note:</strong> Destroying the video encoder closes it implicitly,
 172   /// so you are not required to call Close().
 173   void Close();
 174 };
 175
 176 }  // namespace pp
 177
 178 #endif  // PPAPI_CPP_VIDEO_ENCODER_H_