VAVDA: Redesign stage 1.

content/common/gpu/media/va_surface.h

Index: content/common/gpu/media/va_surface.h
diff --git a/content/common/gpu/media/va_surface.h b/content/common/gpu/media/va_surface.h
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+++ b/content/common/gpu/media/va_surface.h
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+// Copyright (c) 2013 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.
+//
+// This file contains the definition of VASurface class, used for decoding by
+// VaapiVideoDecodeAccelerator and VaapiH264Decoder.
+
+#ifndef CONTENT_COMMON_GPU_MEDIA_VA_SURFACE_H_
+#define CONTENT_COMMON_GPU_MEDIA_VA_SURFACE_H_
+
+#include "third_party/libva/va/va.h"
+
+namespace content {
+
+// A VA-API-specific decode surface used by VaapiH264Decoder to decode into
+// and use as reference for decoding other surfaces. It is also handed by the
+// decoder to VaapiVideoDecodeAccelerator when the contents of the surface are
+// ready and should be displayed. VAVDA converts the surface contents into an
+// X Pixmap bound to a texture for display and releases its reference to it.
+// Decoder releases its references to the surface when it's done decoding and
+// using it as reference. Note that a surface may still be used for reference
+// after it's been sent to output and also after it is no longer used by VAVDA.
+// Thus, the surface can be in use by both VAVDA and the Decoder at the same
+// time, or by either of them, with the restriction that VAVDA will never get
+// the surface until the contents are ready, and it is guaranteed that the
+// contents will not change after that.
+// When both the decoder and VAVDA release their references to the surface,
+// it is freed and the release callback is executed to put the surface back
+// into available surfaces pool, which is managed externally.
+//
+//   VASurfaceID is allocated in VaapiWrapper.
+//        |
+// +----->|
+// |      v
+// | VASurfaceID is put onto VaapiVideoDecodeAccelerator::available_va_surfaces_
+// |      |      list.
+// |      v
+// | VASurfaceID is taken off of the VVDA:available_va_surfaces_ when
+// |      |      VaapiH264Decoder requests more output surfaces, is wrapped into
+// |      |      a VASurface and passed to VaapiH264Decoder.
+// |      v
+// | VASurface is put onto VaapiH264Decoder::available_va_surfaces_, keeping
+// |      |      the only reference to it until it's needed for decoding.
+// |      v
+// | VaapiH264Decoder starts decoding a new frame. It takes a VASurface off of
+// |      |      VHD::available_va_surfaces_ and assigns it to a DecodeSurface,
+// |      |      which now keeps the only reference.
+// |      v
+// | DecodeSurface is used for decoding, putting data into associated VASurface.
+// |      |
+// |      |--------------------------------------------------+
+// |      |                                                  |
+// |      v                                                  v
+// | DecodeSurface is to be output.              VaapiH264Decoder uses the
+// | VaapiH264Decoder passes the associated      DecodeSurface and associated
+// | VASurface to VaapiVideoDecodeAccelerator,   VASurface as reference for
+// | which stores it (taking a ref) on           decoding more frames.
+// | pending_output_cbs_ queue until an output               |
+// | TFPPicture becomes available.                           v
+// |                 |                           Once the DecodeSurface is not
+// |                 |                           needed as reference anymore,
+// |                 v                           it is released, releasing the
+// | A TFPPicture becomes available after        associated VASurface reference.
+// | the client of VVDA returns                              |
+// | a PictureBuffer associated with it. VVDA                |
+// | puts the contents of the VASurface into                 |
+// | it and releases the reference to VASurface.             |
+// |                 |                                       |
+// |                 '---------------------------------------'
+// |                                     |
+// |                                     v
+// | Neither VVDA nor VHD hold a reference to VASurface. VASurface is released,
+// | ReleaseCB gets called in its destructor, which puts the associated
+// | VASurfaceID back onto VVDA::available_va_surfaces_.
+// |                                     |
+// '-------------------------------------|
+//                                       |
+//                                       v
+//                       VaapiWrapper frees VASurfaceID.
+//
+class VASurface : public base::RefCountedThreadSafe<VASurface> {
+ public:
+  // Provided by user, will be called when all references to the surface
+  // are released.
+  typedef base::Callback<void(VASurfaceID)> ReleaseCB;
+
+  VASurface(VASurfaceID va_surface_id, const ReleaseCB& release_cb);
+
+  VASurfaceID id() {
+    return va_surface_id_;
+  }
+
+ private:
+  friend class base::RefCountedThreadSafe<VASurface>;
+  ~VASurface();
+
+  const VASurfaceID va_surface_id_;
+  ReleaseCB release_cb_;
+
+  DISALLOW_COPY_AND_ASSIGN(VASurface);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_COMMON_GPU_MEDIA_VA_SURFACE_H_