content/renderer/media/buffered_data_source.h

   1 // Copyright 2013 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 CONTENT_RENDERER_MEDIA_BUFFERED_DATA_SOURCE_H_
   6 #define CONTENT_RENDERER_MEDIA_BUFFERED_DATA_SOURCE_H_
   7
   8 #include <string>
   9
  10 #include "base/callback.h"
  11 #include "base/memory/scoped_ptr.h"
  12 #include "base/synchronization/lock.h"
  13 #include "content/common/content_export.h"
  14 #include "content/renderer/media/buffered_resource_loader.h"
  15 #include "content/renderer/media/preload.h"
  16 #include "media/base/data_source.h"
  17 #include "media/base/ranges.h"
  18 #include "url/gurl.h"
  19
  20 namespace base {
  21 class MessageLoopProxy;
  22 }
  23
  24 namespace media {
  25 class MediaLog;
  26 }
  27
  28 namespace content {
  29
  30 class CONTENT_EXPORT BufferedDataSourceHost {
  31  public:
  32   // Notify the host of the total size of the media file.
  33   virtual void SetTotalBytes(int64 total_bytes) = 0;
  34
  35   // Notify the host that byte range [start,end] has been buffered.
  36   // TODO(fischman): remove this method when demuxing is push-based instead of
  37   // pull-based.  http://crbug.com/131444
  38   virtual void AddBufferedByteRange(int64 start, int64 end) = 0;
  39
  40  protected:
  41   virtual ~BufferedDataSourceHost() {};
  42 };
  43
  44 // A data source capable of loading URLs and buffering the data using an
  45 // in-memory sliding window.
  46 //
  47 // BufferedDataSource must be created and initialized on the render thread
  48 // before being passed to other threads. It may be deleted on any thread.
  49 class CONTENT_EXPORT BufferedDataSource : public media::DataSource {
  50  public:
  51   typedef base::Callback<void(bool)> DownloadingCB;
  52
  53   // |url| and |cors_mode| are passed to the object. Buffered byte range changes
  54   // will be reported to |host|. |downloading_cb| will be called whenever the
  55   // downloading/paused state of the source changes.
  56   BufferedDataSource(const GURL& url,
  57                      BufferedResourceLoader::CORSMode cors_mode,
  58                      const scoped_refptr<base::MessageLoopProxy>& render_loop,
  59                      blink::WebFrame* frame,
  60                      media::MediaLog* media_log,
  61                      BufferedDataSourceHost* host,
  62                      const DownloadingCB& downloading_cb);
  63   virtual ~BufferedDataSource();
  64
  65   // Executes |init_cb| with the result of initialization when it has completed.
  66   //
  67   // Method called on the render thread.
  68   typedef base::Callback<void(bool)> InitializeCB;
  69   void Initialize(const InitializeCB& init_cb);
  70
  71   // Adjusts the buffering algorithm based on the given preload value.
  72   void SetPreload(Preload preload);
  73
  74   // Returns true if the media resource has a single origin, false otherwise.
  75   // Only valid to call after Initialize() has completed.
  76   //
  77   // Method called on the render thread.
  78   bool HasSingleOrigin();
  79
  80   // Returns true if the media resource passed a CORS access control check.
  81   bool DidPassCORSAccessCheck() const;
  82
  83   // Cancels initialization, any pending loaders, and any pending read calls
  84   // from the demuxer. The caller is expected to release its reference to this
  85   // object and never call it again.
  86   //
  87   // Method called on the render thread.
  88   void Abort();
  89
  90   // Notifies changes in playback state for controlling media buffering
  91   // behavior.
  92   void MediaPlaybackRateChanged(float playback_rate);
  93   void MediaIsPlaying();
  94   void MediaIsPaused();
  95
  96   // Returns true if the resource is local.
  97   bool assume_fully_buffered() { return !url_.SchemeIsHTTPOrHTTPS(); }
  98
  99   // media::DataSource implementation.
 100   // Called from demuxer thread.
 101   virtual void Stop(const base::Closure& closure) OVERRIDE;
 102
 103   virtual void Read(int64 position, int size, uint8* data,
 104                     const media::DataSource::ReadCB& read_cb) OVERRIDE;
 105   virtual bool GetSize(int64* size_out) OVERRIDE;
 106   virtual bool IsStreaming() OVERRIDE;
 107   virtual void SetBitrate(int bitrate) OVERRIDE;
 108
 109  protected:
 110   // A factory method to create a BufferedResourceLoader based on the read
 111   // parameters. We can override this file to object a mock
 112   // BufferedResourceLoader for testing.
 113   virtual BufferedResourceLoader* CreateResourceLoader(
 114       int64 first_byte_position, int64 last_byte_position);
 115
 116  private:
 117   friend class BufferedDataSourceTest;
 118
 119   // Task posted to perform actual reading on the render thread.
 120   void ReadTask();
 121
 122   // Cancels oustanding callbacks and sets |stop_signal_received_|. Safe to call
 123   // from any thread.
 124   void StopInternal_Locked();
 125
 126   // Stops |loader_| if present. Used by Abort() and Stop().
 127   void StopLoader();
 128
 129   // Tells |loader_| the bitrate of the media.
 130   void SetBitrateTask(int bitrate);
 131
 132   // The method that performs actual read. This method can only be executed on
 133   // the render thread.
 134   void ReadInternal();
 135
 136   // BufferedResourceLoader::Start() callback for initial load.
 137   void StartCallback(BufferedResourceLoader::Status status);
 138
 139   // BufferedResourceLoader::Start() callback for subsequent loads (i.e.,
 140   // when accessing ranges that are outside initial buffered region).
 141   void PartialReadStartCallback(BufferedResourceLoader::Status status);
 142
 143   // BufferedResourceLoader callbacks.
 144   void ReadCallback(BufferedResourceLoader::Status status, int bytes_read);
 145   void LoadingStateChangedCallback(BufferedResourceLoader::LoadingState state);
 146   void ProgressCallback(int64 position);
 147
 148   // Update |loader_|'s deferring strategy in response to a play/pause, or
 149   // change in playback rate.
 150   void UpdateDeferStrategy(bool paused);
 151
 152   // URL of the resource requested.
 153   GURL url_;
 154   // crossorigin attribute on the corresponding HTML media element, if any.
 155   BufferedResourceLoader::CORSMode cors_mode_;
 156
 157   // The total size of the resource. Set during StartCallback() if the size is
 158   // known, otherwise it will remain kPositionNotSpecified until the size is
 159   // determined by reaching EOF.
 160   int64 total_bytes_;
 161
 162   // This value will be true if this data source can only support streaming.
 163   // i.e. range request is not supported.
 164   bool streaming_;
 165
 166   // A webframe for loading.
 167   blink::WebFrame* frame_;
 168
 169   // A resource loader for the media resource.
 170   scoped_ptr<BufferedResourceLoader> loader_;
 171
 172   // Callback method from the pipeline for initialization.
 173   InitializeCB init_cb_;
 174
 175   // Read parameters received from the Read() method call. Must be accessed
 176   // under |lock_|.
 177   class ReadOperation;
 178   scoped_ptr<ReadOperation> read_op_;
 179
 180   // This buffer is intermediate, we use it for BufferedResourceLoader to write
 181   // to. And when read in BufferedResourceLoader is done, we copy data from
 182   // this buffer to |read_buffer_|. The reason for an additional copy is that
 183   // we don't own |read_buffer_|. But since the read operation is asynchronous,
 184   // |read_buffer| can be destroyed at any time, so we only copy into
 185   // |read_buffer| in the final step when it is safe.
 186   // Memory is allocated for this member during initialization of this object
 187   // because we want buffer to be passed into BufferedResourceLoader to be
 188   // always non-null. And by initializing this member with a default size we can
 189   // avoid creating zero-sized buffered if the first read has zero size.
 190   scoped_ptr<uint8[]> intermediate_read_buffer_;
 191   int intermediate_read_buffer_size_;
 192
 193   // The message loop of the render thread.
 194   const scoped_refptr<base::MessageLoopProxy> render_loop_;
 195
 196   // Protects |stop_signal_received_| and |read_op_|.
 197   base::Lock lock_;
 198
 199   // Whether we've been told to stop via Abort() or Stop().
 200   bool stop_signal_received_;
 201
 202   // This variable is true when the user has requested the video to play at
 203   // least once.
 204   bool media_has_played_;
 205
 206   // This variable holds the value of the preload attribute for the video
 207   // element.
 208   Preload preload_;
 209
 210   // Bitrate of the content, 0 if unknown.
 211   int bitrate_;
 212
 213   // Current playback rate.
 214   float playback_rate_;
 215
 216   scoped_refptr<media::MediaLog> media_log_;
 217
 218   // Host object to report buffered byte range changes to.
 219   BufferedDataSourceHost* host_;
 220
 221   DownloadingCB downloading_cb_;
 222
 223   // NOTE: Weak pointers must be invalidated before all other member variables.
 224   base::WeakPtrFactory<BufferedDataSource> weak_factory_;
 225
 226   DISALLOW_COPY_AND_ASSIGN(BufferedDataSource);
 227 };
 228
 229 }  // namespace content
 230
 231 #endif  // CONTENT_RENDERER_MEDIA_BUFFERED_DATA_SOURCE_H_