[PPAPI][MediaStream] Support configure for video input.

ppapi/examples/media_stream_video/media_stream_video.cc

 // 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.
 
+#include <vector>
+
 #include "ppapi/c/pp_errors.h"
 #include "ppapi/c/ppb_opengles2.h"
 #include "ppapi/cpp/completion_callback.h"
 #include "ppapi/cpp/graphics_3d.h"
 #include "ppapi/cpp/graphics_3d_client.h"
 #include "ppapi/cpp/instance.h"
 #include "ppapi/cpp/media_stream_video_track.h"
 #include "ppapi/cpp/module.h"
 #include "ppapi/cpp/rect.h"
 #include "ppapi/cpp/var.h"
 #include "ppapi/cpp/video_frame.h"
 #include "ppapi/lib/gl/include/GLES2/gl2.h"
+#include "ppapi/lib/gl/include/GLES2/gl2ext.h"
 #include "ppapi/utility/completion_callback_factory.h"
 
 // When compiling natively on Windows, PostMessage can be #define-d to
 // something else.
 #ifdef PostMessage
 #undef PostMessage
 #endif
 
 // Assert |context_| isn't holding any GL Errors.  Done as a macro instead of a
 // function to preserve line number information in the failure message.
@@ skipping 19 matching lines @@
   virtual ~MediaStreamVideoDemoInstance();
 
   // pp::Instance implementation (see PPP_Instance).
   virtual void DidChangeView(const pp::Rect& position,
                              const pp::Rect& clip_ignored);
   virtual void HandleMessage(const pp::Var& message_data);
 
   // pp::Graphics3DClient implementation.
   virtual void Graphics3DContextLost() {
     InitGL();
-    CreateYUVTextures();
+    CreateTextures();
     Render();
   }
 
  private:
+  void DrawYUV();
+  void DrawRGB();
   void Render();
 
   // GL-related functions.
   void InitGL();
-  GLuint CreateTexture(int32_t width, int32_t height, int unit);
+  GLuint CreateTexture(int32_t width, int32_t height, int unit, bool rgba);
   void CreateGLObjects();
   void CreateShader(GLuint program, GLenum type, const char* source, int size);
   void PaintFinished(int32_t result);
-  void CreateYUVTextures();
+  void CreateTextures();
+  void ConfigureTrack();
 
-  // Callback that is invoked when new frames are recevied.
+
+  // MediaStreamVideoTrack callbacks.
+  void OnConfigure(int32_t result);
   void OnGetFrame(int32_t result, pp::VideoFrame frame);
 
   pp::Size position_size_;
   bool is_painting_;
   bool needs_paint_;
+  bool is_bgra_;
+  GLuint program_yuv_;
+  GLuint program_rgb_;
+  GLuint buffer_;
   GLuint texture_y_;
   GLuint texture_u_;
   GLuint texture_v_;
+  GLuint texture_rgb_;
   pp::MediaStreamVideoTrack video_track_;
   pp::CompletionCallbackFactory<MediaStreamVideoDemoInstance> callback_factory_;
+  std::vector<int32_t> attrib_list_;
+
+  // MediaStreamVideoTrack attributes:
+  bool need_config_;
+  PP_VideoFrame_Format attrib_format_;
+  int32_t attrib_width_;
+  int32_t attrib_height_;
 
   // Unowned pointers.
   const struct PPB_OpenGLES2* gles2_if_;
 
   // Owned data.
   pp::Graphics3D* context_;
 
   pp::Size frame_size_;
 };
 
 MediaStreamVideoDemoInstance::MediaStreamVideoDemoInstance(
     PP_Instance instance, pp::Module* module)
     : pp::Instance(instance),
       pp::Graphics3DClient(this),
       is_painting_(false),
       needs_paint_(false),
+      is_bgra_(false),
       texture_y_(0),
       texture_u_(0),
       texture_v_(0),
+      texture_rgb_(0),
       callback_factory_(this),
+      need_config_(false),
+      attrib_format_(PP_VIDEOFRAME_FORMAT_I420),
+      attrib_width_(0),
+      attrib_height_(0),
       context_(NULL) {
   gles2_if_ = static_cast<const struct PPB_OpenGLES2*>(
       module->GetBrowserInterface(PPB_OPENGLES2_INTERFACE));
   PP_DCHECK(gles2_if_);
 }
 
 MediaStreamVideoDemoInstance::~MediaStreamVideoDemoInstance() {
   delete context_;
 }
 
 void MediaStreamVideoDemoInstance::DidChangeView(
     const pp::Rect& position, const pp::Rect& clip_ignored) {
   if (position.width() == 0 || position.height() == 0)
     return;
   if (position.size() == position_size_)
     return;
 
   position_size_ = position.size();
 
   // Initialize graphics.
   InitGL();
   Render();
 }
 
 void MediaStreamVideoDemoInstance::HandleMessage(const pp::Var& var_message) {
   if (!var_message.is_dictionary())
     return;
+
   pp::VarDictionary var_dictionary_message(var_message);
-  pp::Var var_track = var_dictionary_message.Get("track");
-  if (!var_track.is_resource())
-    return;
+  std::string command = var_dictionary_message.Get("command").AsString();
 
-  pp::Resource resource_track = var_track.AsResource();
-
-  video_track_ = pp::MediaStreamVideoTrack(resource_track);
-
-  video_track_.GetFrame(callback_factory_.NewCallbackWithOutput(
-        &MediaStreamVideoDemoInstance::OnGetFrame));
+  if (command == "init") {
+    pp::Var var_track = var_dictionary_message.Get("track");
+    if (!var_track.is_resource())
+      return;
+    pp::Resource resource_track = var_track.AsResource();
+    video_track_ = pp::MediaStreamVideoTrack(resource_track);
+    ConfigureTrack();
+  } else if (command == "format") {
+    std::string str_format =  var_dictionary_message.Get("format").AsString();
+    if (str_format == "YV12") {
+      attrib_format_ = PP_VIDEOFRAME_FORMAT_YV12;
+    } else if (str_format == "I420") {
+      attrib_format_ = PP_VIDEOFRAME_FORMAT_I420;
+    } else if (str_format == "BGRA") {
+      attrib_format_ = PP_VIDEOFRAME_FORMAT_BGRA;
+    } else {
+      attrib_format_ = PP_VIDEOFRAME_FORMAT_UNKNOWN;
+    }
+    need_config_ = true;
+  } else if (command == "size") {
+    attrib_width_ = var_dictionary_message.Get("width").AsInt();
+    attrib_height_ = var_dictionary_message.Get("height").AsInt();
+    need_config_ = true;
+  }
 }
 
 void MediaStreamVideoDemoInstance::InitGL() {
   PP_DCHECK(position_size_.width() && position_size_.height());
   is_painting_ = false;
 
   delete context_;
   int32_t attributes[] = {
     PP_GRAPHICS3DATTRIB_ALPHA_SIZE, 0,
     PP_GRAPHICS3DATTRIB_BLUE_SIZE, 8,
@@ skipping 15 matching lines @@
   gles2_if_->Clear(context_->pp_resource(), GL_COLOR_BUFFER_BIT);
   gles2_if_->Viewport(context_->pp_resource(), 0, 0,
                       position_size_.width(), position_size_.height());
 
   BindGraphics(*context_);
   AssertNoGLError();
 
   CreateGLObjects();
 }
 
+void MediaStreamVideoDemoInstance::DrawYUV() {
+  PP_Resource context = context_->pp_resource();
+  static const float kColorMatrix[9] = {
+    1.1643828125f, 1.1643828125f, 1.1643828125f,
+    0.0f, -0.39176171875f, 2.017234375f,
+    1.59602734375f, -0.81296875f, 0.0f
+  };
+
+  gles2_if_->UseProgram(context, program_yuv_);
+  gles2_if_->Uniform1i(context, gles2_if_->GetUniformLocation(
+        context, program_yuv_, "y_texture"), 0);
+  gles2_if_->Uniform1i(context, gles2_if_->GetUniformLocation(
+        context, program_yuv_, "u_texture"), 1);
+  gles2_if_->Uniform1i(context, gles2_if_->GetUniformLocation(
+        context, program_yuv_, "v_texture"), 2);
+  gles2_if_->UniformMatrix3fv(
+      context,
+      gles2_if_->GetUniformLocation(context, program_yuv_, "color_matrix"),
+      1, GL_FALSE, kColorMatrix);
+  AssertNoGLError();
+
+  GLint pos_location = gles2_if_->GetAttribLocation(
+      context, program_yuv_, "a_position");
+  GLint tc_location = gles2_if_->GetAttribLocation(
+      context, program_yuv_, "a_texCoord");
+  AssertNoGLError();
+  gles2_if_->EnableVertexAttribArray(context, pos_location);
+  gles2_if_->VertexAttribPointer(context, pos_location, 2,
+                                 GL_FLOAT, GL_FALSE, 0, 0);
+  gles2_if_->EnableVertexAttribArray(context, tc_location);
+  gles2_if_->VertexAttribPointer(
+      context, tc_location, 2, GL_FLOAT, GL_FALSE, 0,
+      static_cast<float*>(0) + 16);  // Skip position coordinates.
+  AssertNoGLError();
+
+  gles2_if_->DrawArrays(context, GL_TRIANGLE_STRIP, 0, 4);
+  AssertNoGLError();
+}
+
+void MediaStreamVideoDemoInstance::DrawRGB() {
+  PP_Resource context = context_->pp_resource();
+  gles2_if_->UseProgram(context, program_rgb_);
+  gles2_if_->Uniform1i(context,
+      gles2_if_->GetUniformLocation(context, program_rgb_, "rgb_texture"), 3);
+  AssertNoGLError();
+
+  GLint pos_location = gles2_if_->GetAttribLocation(
+      context, program_rgb_, "a_position");
+  GLint tc_location = gles2_if_->GetAttribLocation(
+      context, program_rgb_, "a_texCoord");
+  AssertNoGLError();
+  gles2_if_->EnableVertexAttribArray(context, pos_location);
+  gles2_if_->VertexAttribPointer(context, pos_location, 2,
+                                 GL_FLOAT, GL_FALSE, 0, 0);
+  gles2_if_->EnableVertexAttribArray(context, tc_location);
+  gles2_if_->VertexAttribPointer(
+      context, tc_location, 2, GL_FLOAT, GL_FALSE, 0,
+      static_cast<float*>(0) + 16);  // Skip position coordinates.
+  AssertNoGLError();
+
+  gles2_if_->DrawArrays(context, GL_TRIANGLE_STRIP, 4, 4);
+}
+
 void MediaStreamVideoDemoInstance::Render() {
   PP_DCHECK(!is_painting_);
   is_painting_ = true;
   needs_paint_ = false;
+
   if (texture_y_) {
-    gles2_if_->DrawArrays(context_->pp_resource(), GL_TRIANGLE_STRIP, 0, 4);
+    DrawRGB();
+    DrawYUV();
   } else {
     gles2_if_->Clear(context_->pp_resource(), GL_COLOR_BUFFER_BIT);
   }
   pp::CompletionCallback cb = callback_factory_.NewCallback(
       &MediaStreamVideoDemoInstance::PaintFinished);
   context_->SwapBuffers(cb);
 }
 
 void MediaStreamVideoDemoInstance::PaintFinished(int32_t result) {
   is_painting_ = false;
   if (needs_paint_)
     Render();
 }
 
 GLuint MediaStreamVideoDemoInstance::CreateTexture(
-    int32_t width, int32_t height, int unit) {
+    int32_t width, int32_t height, int unit, bool rgba) {
   GLuint texture_id;
   gles2_if_->GenTextures(context_->pp_resource(), 1, &texture_id);
   AssertNoGLError();
+
   // Assign parameters.
   gles2_if_->ActiveTexture(context_->pp_resource(), GL_TEXTURE0 + unit);
   gles2_if_->BindTexture(context_->pp_resource(), GL_TEXTURE_2D, texture_id);
   gles2_if_->TexParameteri(
       context_->pp_resource(), GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER,
       GL_NEAREST);
   gles2_if_->TexParameteri(
       context_->pp_resource(), GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER,
       GL_NEAREST);
   gles2_if_->TexParameterf(
       context_->pp_resource(), GL_TEXTURE_2D, GL_TEXTURE_WRAP_S,
       GL_CLAMP_TO_EDGE);
   gles2_if_->TexParameterf(
       context_->pp_resource(), GL_TEXTURE_2D, GL_TEXTURE_WRAP_T,
       GL_CLAMP_TO_EDGE);
-
   // Allocate texture.
   gles2_if_->TexImage2D(
-      context_->pp_resource(), GL_TEXTURE_2D, 0, GL_LUMINANCE, width, height, 0,
-      GL_LUMINANCE, GL_UNSIGNED_BYTE, NULL);
+      context_->pp_resource(), GL_TEXTURE_2D, 0,
+      rgba ? GL_BGRA_EXT : GL_LUMINANCE,
+      width, height, 0,
+      rgba ? GL_BGRA_EXT : GL_LUMINANCE, GL_UNSIGNED_BYTE, NULL);
   AssertNoGLError();
   return texture_id;
 }
 
 void MediaStreamVideoDemoInstance::CreateGLObjects() {
   // Code and constants for shader.
   static const char kVertexShader[] =
       "varying vec2 v_texCoord;            \n"
       "attribute vec4 a_position;          \n"
       "attribute vec2 a_texCoord;          \n"
       "void main()                         \n"
       "{                                   \n"
       "    v_texCoord = a_texCoord;        \n"
       "    gl_Position = a_position;       \n"
       "}";
 
-  static const char kFragmentShader[] =
+  static const char kFragmentShaderYUV[] =
       "precision mediump float;                                   \n"
       "varying vec2 v_texCoord;                                   \n"
       "uniform sampler2D y_texture;                               \n"
       "uniform sampler2D u_texture;                               \n"
       "uniform sampler2D v_texture;                               \n"
       "uniform mat3 color_matrix;                                 \n"
       "void main()                                                \n"
       "{                                                          \n"
       "  vec3 yuv;                                                \n"
       "  yuv.x = texture2D(y_texture, v_texCoord).r;              \n"
       "  yuv.y = texture2D(u_texture, v_texCoord).r;              \n"
       "  yuv.z = texture2D(v_texture, v_texCoord).r;              \n"
       "  vec3 rgb = color_matrix * (yuv - vec3(0.0625, 0.5, 0.5));\n"
       "  gl_FragColor = vec4(rgb, 1.0);                           \n"
       "}";
 
-  static const float kColorMatrix[9] = {
-    1.1643828125f, 1.1643828125f, 1.1643828125f,
-    0.0f, -0.39176171875f, 2.017234375f,
-    1.59602734375f, -0.81296875f, 0.0f
-  };
+  static const char kFragmentShaderRGB[] =
+      "precision mediump float;                                   \n"
+      "varying vec2 v_texCoord;                                   \n"
+      "uniform sampler2D rgb_texture;                             \n"
+      "void main()                                                \n"
+      "{                                                          \n"
+      "  gl_FragColor = texture2D(rgb_texture, v_texCoord);       \n"
+      "}";
 
   PP_Resource context = context_->pp_resource();
 
-  // Create shader program.
-  GLuint program = gles2_if_->CreateProgram(context);
-  CreateShader(program, GL_VERTEX_SHADER, kVertexShader, sizeof(kVertexShader));
-  CreateShader(
-      program, GL_FRAGMENT_SHADER, kFragmentShader, sizeof(kFragmentShader));
-  gles2_if_->LinkProgram(context, program);
-  gles2_if_->UseProgram(context, program);
-  gles2_if_->DeleteProgram(context, program);
-  gles2_if_->Uniform1i(
-      context, gles2_if_->GetUniformLocation(context, program, "y_texture"), 0);
-  gles2_if_->Uniform1i(
-      context, gles2_if_->GetUniformLocation(context, program, "u_texture"), 1);
-  gles2_if_->Uniform1i(
-      context, gles2_if_->GetUniformLocation(context, program, "v_texture"), 2);
-  gles2_if_->UniformMatrix3fv(
-      context,
-      gles2_if_->GetUniformLocation(context, program, "color_matrix"),
-      1, GL_FALSE, kColorMatrix);
+  // Create shader programs.
+  program_yuv_ = gles2_if_->CreateProgram(context);
+  CreateShader(program_yuv_, GL_VERTEX_SHADER,
+               kVertexShader, sizeof(kVertexShader));
+  CreateShader(program_yuv_, GL_FRAGMENT_SHADER,
+               kFragmentShaderYUV, sizeof(kFragmentShaderYUV));
+  gles2_if_->LinkProgram(context, program_yuv_);
+  AssertNoGLError();
+
+  program_rgb_ = gles2_if_->CreateProgram(context);
+  CreateShader(program_rgb_, GL_VERTEX_SHADER,
+               kVertexShader, sizeof(kVertexShader));
+  CreateShader(program_rgb_, GL_FRAGMENT_SHADER,
+               kFragmentShaderRGB, sizeof(kFragmentShaderRGB));
+  gles2_if_->LinkProgram(context, program_rgb_);
   AssertNoGLError();
 
   // Assign vertex positions and texture coordinates to buffers for use in
   // shader program.
   static const float kVertices[] = {
-    -1, 1, -1, -1, 1, 1, 1, -1,  // Position coordinates.
+    -1, 1, -1, -1, 0, 1, 0, -1,  // Position coordinates.
+    0, 1, 0, -1, 1, 1, 1, -1,  // Position coordinates.
+    0, 0, 0, 1, 1, 0, 1, 1,  // Texture coordinates.
     0, 0, 0, 1, 1, 0, 1, 1,  // Texture coordinates.
   };
 
-  GLuint buffer;
-  gles2_if_->GenBuffers(context, 1, &buffer);
-  gles2_if_->BindBuffer(context, GL_ARRAY_BUFFER, buffer);
+  gles2_if_->GenBuffers(context, 1, &buffer_);
+  gles2_if_->BindBuffer(context, GL_ARRAY_BUFFER, buffer_);
   gles2_if_->BufferData(context, GL_ARRAY_BUFFER,
                         sizeof(kVertices), kVertices, GL_STATIC_DRAW);
   AssertNoGLError();
-  GLint pos_location = gles2_if_->GetAttribLocation(
-      context, program, "a_position");
-  GLint tc_location = gles2_if_->GetAttribLocation(
-      context, program, "a_texCoord");
-  AssertNoGLError();
-  gles2_if_->EnableVertexAttribArray(context, pos_location);
-  gles2_if_->VertexAttribPointer(context, pos_location, 2,
-                                 GL_FLOAT, GL_FALSE, 0, 0);
-  gles2_if_->EnableVertexAttribArray(context, tc_location);
-  gles2_if_->VertexAttribPointer(
-      context, tc_location, 2, GL_FLOAT, GL_FALSE, 0,
-      static_cast<float*>(0) + 8);  // Skip position coordinates.
-  AssertNoGLError();
 }
 
 void MediaStreamVideoDemoInstance::CreateShader(
     GLuint program, GLenum type, const char* source, int size) {
   PP_Resource context = context_->pp_resource();
   GLuint shader = gles2_if_->CreateShader(context, type);
   gles2_if_->ShaderSource(context, shader, 1, &source, &size);
   gles2_if_->CompileShader(context, shader);
   gles2_if_->AttachShader(context, program, shader);
   gles2_if_->DeleteShader(context, shader);
 }
 
-void MediaStreamVideoDemoInstance::CreateYUVTextures() {
+void MediaStreamVideoDemoInstance::CreateTextures() {
   int32_t width = frame_size_.width();
   int32_t height = frame_size_.height();
   if (width == 0 || height == 0)
     return;
   if (texture_y_)
     gles2_if_->DeleteTextures(context_->pp_resource(), 1, &texture_y_);
   if (texture_u_)
     gles2_if_->DeleteTextures(context_->pp_resource(), 1, &texture_u_);
   if (texture_v_)
     gles2_if_->DeleteTextures(context_->pp_resource(), 1, &texture_v_);
-  texture_y_ = CreateTexture(width, height, 0);
+  if (texture_rgb_)
+    gles2_if_->DeleteTextures(context_->pp_resource(), 1, &texture_rgb_);
+  texture_y_ = CreateTexture(width, height, 0, false);
 
-  width /= 2;
-  height /= 2;
-  texture_u_ = CreateTexture(width, height, 1);
-  texture_v_ = CreateTexture(width, height, 2);
+  texture_u_ = CreateTexture(width / 2, height / 2, 1, false);
+  texture_v_ = CreateTexture(width / 2, height / 2, 2, false);
+  texture_rgb_ = CreateTexture(width, height, 3, true);
+}
+
+void MediaStreamVideoDemoInstance::ConfigureTrack() {
+  const int32_t attrib_list[] = {
+      PP_MEDIASTREAMVIDEOTRACK_ATTRIB_FORMAT, attrib_format_,
+      PP_MEDIASTREAMVIDEOTRACK_ATTRIB_WIDTH, attrib_width_,
+      PP_MEDIASTREAMVIDEOTRACK_ATTRIB_HEIGHT, attrib_height_,
+      PP_MEDIASTREAMVIDEOTRACK_ATTRIB_NONE
+    };
+  video_track_.Configure(attrib_list, callback_factory_.NewCallback(
+        &MediaStreamVideoDemoInstance::OnConfigure));
+}
+
+void MediaStreamVideoDemoInstance::OnConfigure(int32_t result) {
+  video_track_.GetFrame(callback_factory_.NewCallbackWithOutput(
+      &MediaStreamVideoDemoInstance::OnGetFrame));
 }
 
 void MediaStreamVideoDemoInstance::OnGetFrame(
     int32_t result, pp::VideoFrame frame) {
   if (result != PP_OK)
     return;
   const char* data = static_cast<const char*>(frame.GetDataBuffer());
   pp::Size size;
   frame.GetSize(&size);
 
   if (size != frame_size_) {
     frame_size_ = size;
-    CreateYUVTextures();
+    CreateTextures();
   }
 
+  is_bgra_ = (frame.GetFormat() == PP_VIDEOFRAME_FORMAT_BGRA);
+
   int32_t width = frame_size_.width();
   int32_t height = frame_size_.height();
-  gles2_if_->ActiveTexture(context_->pp_resource(), GL_TEXTURE0);
-  gles2_if_->TexSubImage2D(
-      context_->pp_resource(), GL_TEXTURE_2D, 0, 0, 0, width, height,
-      GL_LUMINANCE, GL_UNSIGNED_BYTE, data);
+  if (!is_bgra_) {
+    gles2_if_->ActiveTexture(context_->pp_resource(), GL_TEXTURE0);
+    gles2_if_->TexSubImage2D(
+        context_->pp_resource(), GL_TEXTURE_2D, 0, 0, 0, width, height,
+        GL_LUMINANCE, GL_UNSIGNED_BYTE, data);
 
-  data += width * height;
-  width /= 2;
-  height /= 2;
+    data += width * height;
+    width /= 2;
+    height /= 2;
 
-  gles2_if_->ActiveTexture(context_->pp_resource(), GL_TEXTURE1);
-  gles2_if_->TexSubImage2D(
-      context_->pp_resource(), GL_TEXTURE_2D, 0, 0, 0, width, height,
-      GL_LUMINANCE, GL_UNSIGNED_BYTE, data);
+    gles2_if_->ActiveTexture(context_->pp_resource(), GL_TEXTURE1);
+    gles2_if_->TexSubImage2D(
+        context_->pp_resource(), GL_TEXTURE_2D, 0, 0, 0, width, height,
+        GL_LUMINANCE, GL_UNSIGNED_BYTE, data);
 
-  data += width * height;
-  gles2_if_->ActiveTexture(context_->pp_resource(), GL_TEXTURE2);
-  gles2_if_->TexSubImage2D(
-      context_->pp_resource(), GL_TEXTURE_2D, 0, 0, 0, width, height,
-      GL_LUMINANCE, GL_UNSIGNED_BYTE, data);
+    data += width * height;
+    gles2_if_->ActiveTexture(context_->pp_resource(), GL_TEXTURE2);
+    gles2_if_->TexSubImage2D(
+        context_->pp_resource(), GL_TEXTURE_2D, 0, 0, 0, width, height,
+        GL_LUMINANCE, GL_UNSIGNED_BYTE, data);
+  } else {
+    gles2_if_->ActiveTexture(context_->pp_resource(), GL_TEXTURE3);
+    gles2_if_->TexSubImage2D(
+        context_->pp_resource(), GL_TEXTURE_2D, 0, 0, 0, width, height,
+        GL_BGRA_EXT, GL_UNSIGNED_BYTE, data);
+  }
 
   if (is_painting_)
     needs_paint_ = true;
   else
     Render();
 
   video_track_.RecycleFrame(frame);
-  video_track_.GetFrame(callback_factory_.NewCallbackWithOutput(
-      &MediaStreamVideoDemoInstance::OnGetFrame));
+  if (need_config_) {
+    ConfigureTrack();
+    need_config_ = false;
+  } else {
+    video_track_.GetFrame(callback_factory_.NewCallbackWithOutput(
+        &MediaStreamVideoDemoInstance::OnGetFrame));
+  }
 }
 
 pp::Instance* MediaStreamVideoModule::CreateInstance(PP_Instance instance) {
   return new MediaStreamVideoDemoInstance(instance, this);
 }
 
 }  // anonymous namespace
 
 namespace pp {
 // Factory function for your specialization of the Module object.
 Module* CreateModule() {
   return new MediaStreamVideoModule();
 }
 }  // namespace pp