Implement Pepper PPB_VideoDecoder interface.

ppapi/proxy/video_decoder_resource.h

Index: ppapi/proxy/video_decoder_resource.h
diff --git a/ppapi/proxy/video_decoder_resource.h b/ppapi/proxy/video_decoder_resource.h
new file mode 100644
index 0000000000000000000000000000000000000000..01fe05ff7b15b121fe8984c63b7161ddb8be268a
--- /dev/null
+++ b/ppapi/proxy/video_decoder_resource.h
@@ -0,0 +1,180 @@
+// Copyright (c) 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.
+
+#ifndef PPAPI_PROXY_VIDEO_DECODER_RESOURCE_H_
+#define PPAPI_PROXY_VIDEO_DECODER_RESOURCE_H_
+
+#include <queue>
+
+#include "base/containers/hash_tables.h"
+#include "base/memory/ref_counted.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/memory/scoped_vector.h"
+#include "ppapi/proxy/connection.h"
+#include "ppapi/proxy/plugin_resource.h"
+#include "ppapi/proxy/ppapi_proxy_export.h"
+#include "ppapi/shared_impl/resource.h"
+#include "ppapi/shared_impl/scoped_pp_resource.h"
+#include "ppapi/thunk/ppb_video_decoder_api.h"
+
+namespace gpu {
+namespace gles2 {
+class GLES2Implementation;
+}
+}
+
+namespace ppapi {
+
+class PPB_Graphics3D_Shared;
+class TrackedCallback;
+
+namespace proxy {
+
+class PPAPI_PROXY_EXPORT VideoDecoderResource
+    : public PluginResource,
+      public thunk::PPB_VideoDecoder_API {
+ public:
+  VideoDecoderResource(Connection connection, PP_Instance instance);
+  virtual ~VideoDecoderResource();
+
+  // Resource overrides.
+  virtual thunk::PPB_VideoDecoder_API* AsPPB_VideoDecoder_API() OVERRIDE;
+
+  // PPB_VideoDecoder_API implementation.
+  virtual int32_t Initialize(PP_Resource graphics_context,
+                             PP_VideoProfile profile,
+                             PP_Bool allow_software_fallback,
+                             scoped_refptr<TrackedCallback> callback) OVERRIDE;
+  virtual int32_t Decode(uint32_t decode_id,
+                         uint32_t size,
+                         const void* buffer,
+                         scoped_refptr<TrackedCallback> callback) OVERRIDE;
+  virtual int32_t GetPicture(PP_VideoPicture* picture,
+                             scoped_refptr<TrackedCallback> callback) OVERRIDE;
+  virtual void RecyclePicture(const PP_VideoPicture* picture) OVERRIDE;
+  virtual int32_t Flush(scoped_refptr<TrackedCallback> callback) OVERRIDE;
+  virtual int32_t Reset(scoped_refptr<TrackedCallback> callback) OVERRIDE;
+
+  // PluginResource implementation.
+  virtual void OnReplyReceived(const ResourceMessageReplyParams& params,
+                               const IPC::Message& msg) OVERRIDE;
+
+  // Called only by unit tests. This bypasses Graphics3D setup, which doesn't
+  // work in ppapi::proxy::PluginProxyTest.
+  void SetForTest();
+
+ private:
+  // Struct to hold a shared memory buffer.
+  struct ShmBuffer {
+    ShmBuffer(scoped_ptr<base::SharedMemory> shm,
+              uint32_t size,
+              uint32_t shm_id);
+    ~ShmBuffer();
+
+    scoped_ptr<base::SharedMemory> shm;
+    void* addr;
+    // Index into shm_buffers_ vector, used as an id. This should map 1:1 to
+    // the index on the host side of the proxy.
+    uint32_t shm_id;
+  };
+
+  // Struct to hold texture information.
+  struct Texture {
+    Texture(uint32_t texture_target, const PP_Size& size);
+    ~Texture();
+
+    uint32_t texture_target;
+    PP_Size size;
+  };
+
+  // Struct to hold a picture received from the decoder.
+  struct Picture {
+    Picture(int32_t decode_id, uint32_t texture_id);
+    ~Picture();
+
+    uint32_t decode_id;
+    uint32_t texture_id;
+  };
+
+  int32_t InitializeInternal(PP_Resource graphics_context,
+                             PP_VideoProfile profile,
+                             PP_Bool allow_software_fallback,
+                             scoped_refptr<TrackedCallback> callback,
+                             bool testing);
+
+  // Unsolicited reply message handlers.
+  void OnPluginMsgRequestTextures(const ResourceMessageReplyParams& params,
+                                  uint32_t num_textures,
+                                  const PP_Size& size,
+                                  uint32_t texture_target);
+  void OnPluginMsgPictureReady(const ResourceMessageReplyParams& params,
+                               uint32_t decode_id,
+                               uint32_t texture_id);
+  void OnPluginMsgDismissPicture(const ResourceMessageReplyParams& params,
+                                 uint32_t texture_id);
+  void OnPluginMsgNotifyError(const ResourceMessageReplyParams& params,
+                              int32_t error);
+
+  // Reply message handlers for operations that are done in the host.
+  void OnPluginMsgInitializeComplete(const ResourceMessageReplyParams& params);
+  void OnPluginMsgDecodeComplete(const ResourceMessageReplyParams& params,
+                                 uint32_t shm_id);
+  void OnPluginMsgFlushComplete(const ResourceMessageReplyParams& params);
+  void OnPluginMsgResetComplete(const ResourceMessageReplyParams& params);
+
+  void RunDecodeCallback(int32_t result);
+  void DeleteGLTexture(uint32_t texture_id);
+  void WriteNextPicture(PP_VideoPicture* picture);
+
+  // ScopedVector to own the shared memory buffers.
+  ScopedVector<ShmBuffer> shm_buffers_;
+
+  // List of available shared memory buffers.
+  typedef std::vector<ShmBuffer*> ShmBufferList;
+  ShmBufferList available_shm_buffers_;
+
+  // Map of GL texture id to texture info.
+  typedef base::hash_map<uint32_t, Texture> TextureMap;
+  TextureMap textures_;
+
+  // Queue of received pictures.
+  typedef std::queue<Picture> PictureQueue;
+  PictureQueue received_pictures_;
+
+  // Pending callbacks.
+  scoped_refptr<TrackedCallback> initialize_callback_;
+  scoped_refptr<TrackedCallback> decode_callback_;
+  scoped_refptr<TrackedCallback> get_picture_callback_;
+  scoped_refptr<TrackedCallback> flush_callback_;
+  scoped_refptr<TrackedCallback> reset_callback_;
+
+  // The maximum delay (in Decode calls) before we receive a picture. If we
+  // haven't received a picture from a Decode call after this many successive
+  // calls to Decode, then we will never receive a picture from the call.
+  // Note that this isn't guaranteed by H264 or other codecs. In practice, this
+  // number is less than 16. We make it much larger just to be safe.

[piman, 2014/05/23 20:07:27]

I think this has more to do with how pipelining works inside of Chrome and the
decoder than the bitstream itself - what prevents the decoder from copying many
buffers (especially if they're small) into its internal pool, before sending
back the first picture?

Should we throttle Decodes to make sure this doesn't happen? Or do we have such
a guarantee at the hardware decoder level?

[bbudge, 2014/05/23 20:57:05]

I chatted with Ami. Chrome uses this number to deal with essentially the same
problem:
https://code.google.com/p/chromium/codesearch#chromium/src/media/filters/gpu_...

I can try to improve the comment if you'd like.

+  static const int kMaximumPictureDelay = 128;
+  // Number of Decode calls made so far. This is in sync with a counter in the
+  // host, and generates a uid for each decode. This number will overflow after
+  // 414 days, assuming 60Hz decodes.
+  int32_t num_decodes_;
+  uint32_t decode_ids_[kMaximumPictureDelay];
+
+  // State for pending get_picture_callback_.
+  PP_VideoPicture* get_picture_;
+
+  ScopedPPResource graphics3d_;
+  gpu::gles2::GLES2Implementation* gles2_impl_;
+
+  bool initialized_;
+  bool testing_;
+  int32_t decoder_last_error_;
+
+  DISALLOW_COPY_AND_ASSIGN(VideoDecoderResource);
+};
+
+}  // namespace proxy
+}  // namespace ppapi
+
+#endif  // PPAPI_PROXY_VIDEO_DECODER_RESOURCE_H_