Begin refactor of AVDA to support zero-copy.

content/common/gpu/media/android_copying_backing_strategy.cc

+// Copyright (c) 2015 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 "content/common/gpu/media/android_copying_backing_strategy.h"
+
+#include "base/bind.h"
+#include "base/logging.h"
+#include "base/message_loop/message_loop.h"
+#include "base/metrics/histogram.h"
+#include "content/common/gpu/gpu_channel.h"
+#include "content/common/gpu/media/avda_return_on_failure.h"
+#include "gpu/command_buffer/service/gles2_cmd_decoder.h"
+#include "media/base/bitstream_buffer.h"
+#include "media/base/limits.h"
+#include "media/base/video_decoder_config.h"
+#include "media/video/picture.h"
+#include "ui/gl/android/surface_texture.h"
+#include "ui/gl/gl_bindings.h"
+
+namespace content {
+
+// TODO(dwkang): We only need kMaxVideoFrames to pass media stack's prerolling
+// phase, but 1 is added due to crbug.com/176036. This should be tuned when we
+// have actual use case.

[sandersd (OOO until July 31), 2015/09/10 20:28:20]

We should probably update all of the copies of this comment because the
referenced bug is both closed and unclear as to the root issue. There is a
specific check for available picture buffers during preroll and we enter
low-delay mode if that happens, so even if the root issue is real I don't think
it can deadlock decoding.

A more current explanation would be more like: We need at least one
PictureBuffer for each buffered frame, plus one for the current frame.
Additional PictureBuffers can only slightly reduce latency while significantly
increasing memory.

[liberato (no reviews please), 2015/09/14 17:41:28]

i saw weirdness when prototyping the zero copy code, with this set to 2.  looked
like a frame was being held outside of the VDA sometimes during playback,
causing a similar deadlock.

i opened a bug to sort it out, and updated the comment correspondingly.

+enum { kNumPictureBuffers = media::limits::kMaxVideoFrames + 1 };
+
+AndroidCopyingBackingStrategy::AndroidCopyingBackingStrategy()
+    : state_provider_(nullptr) {}
+
+AndroidCopyingBackingStrategy::~AndroidCopyingBackingStrategy() {}
+
+void AndroidCopyingBackingStrategy::SetStateProvider(
+    AndroidVideoDecodeAcceleratorStateProvider* state_provider) {
+  state_provider_ = state_provider;
+}
+
+void AndroidCopyingBackingStrategy::Cleanup() {
+  DCHECK(state_provider_->ThreadChecker().CalledOnValidThread());
+  if (copier_)
+    copier_->Destroy();
+}
+
+uint32 AndroidCopyingBackingStrategy::GetNumPictureBuffers() const {
+  return kNumPictureBuffers;
+}
+
+uint32 AndroidCopyingBackingStrategy::GetTextureTarget() const {
+  return GL_TEXTURE_2D;
+}
+
+void AndroidCopyingBackingStrategy::AssignCurrentSurfaceToPictureBuffer(
+    int32 codec_buf_index,
+    const media::PictureBuffer& picture_buffer) {
+  // Make sure that the decoder is available.
+  RETURN_ON_FAILURE(state_provider_, state_provider_->GetGlDecoder(),
+                    "Failed to get gles2 decoder instance.", ILLEGAL_STATE);
+
+  // Render the codec buffer into |surface_texture_|, and switch it to be
+  // the front buffer.
+  // This ignores the emitted ByteBuffer and instead relies on rendering to
+  // the codec's SurfaceTexture and then copying from that texture to the
+  // client's PictureBuffer's texture.  This means that each picture's data
+  // is written three times: once to the ByteBuffer, once to the
+  // SurfaceTexture, and once to the client's texture.  It would be nicer to
+  // either:
+  // 1) Render directly to the client's texture from MediaCodec (one write);
+  //    or
+  // 2) Upload the ByteBuffer to the client's texture (two writes).
+  // Unfortunately neither is possible:
+  // 1) MediaCodec's use of SurfaceTexture is a singleton, and the texture
+  //    written to can't change during the codec's lifetime.  b/11990461
+  // 2) The ByteBuffer is likely to contain the pixels in a vendor-specific,
+  //    opaque/non-standard format.  It's not possible to negotiate the
+  //    decoder to emit a specific colorspace, even using HW CSC.  b/10706245
+  // So, we live with these two extra copies per picture :(
+  state_provider_->GetMediaCodec()->ReleaseOutputBuffer(codec_buf_index, true);
+
+  gfx::SurfaceTexture* surface_texture = state_provider_->GetSurfaceTexture();
+  surface_texture->UpdateTexImage();
+
+  float transfrom_matrix[16];
+  surface_texture->GetTransformMatrix(transfrom_matrix);
+
+  uint32 picture_buffer_texture_id = picture_buffer.texture_id();
+
+  // Defer initializing the CopyTextureCHROMIUMResourceManager until it is
+  // needed because it takes 10s of milliseconds to initialize.
+  if (!copier_) {
+    copier_.reset(new gpu::CopyTextureCHROMIUMResourceManager());
+    copier_->Initialize(state_provider_->GetGlDecoder());
+  }
+
+  // Here, we copy |surface_texture_id_| to the picture buffer instead of
+  // setting new texture to |surface_texture_| by calling attachToGLContext()
+  // because:
+  // 1. Once we call detachFrameGLContext(), it deletes the texture previous
+  //    attached.
+  // 2. SurfaceTexture requires us to apply a transform matrix when we show
+  //    the texture.
+  // TODO(hkuang): get the StreamTexture transform matrix in GPU process
+  // instead of using default matrix crbug.com/226218.
+  const static GLfloat default_matrix[16] = {1.0f, 0.0f, 0.0f, 0.0f, 0.0f, 1.0f,

[qinmin, 2015/09/11 17:29:51]

should this be using the transform_matrix instead?

[liberato (no reviews please), 2015/09/14 17:41:28]

great question.  i want to preserve current behavior with this CL, so i've
opened crbug.com/530681 to track this.

possibly, nobody went back to update this code after crbug.com/226218 was
closed.  i'll see if any of my devices produce a non-identity transform that i
can test against.  if they do, it still has to be pretty close to identity given
that it looks okay.

do you know of any devices that are far enough from identity to be obviously
broken?

[watk, 2015/09/14 18:15:19]

qinmin@ said the xoom has non identity, but I don't have one. I do have access
to a Galaxy S6 which isn't identity and clearly looks wrong, so I could test it.
I'll leave a note on the bug.

+                                             0.0f, 0.0f, 0.0f, 0.0f, 1.0f, 0.0f,
+                                             0.0f, 0.0f, 0.0f, 1.0f};
+  copier_->DoCopyTextureWithTransform(
+      state_provider_->GetGlDecoder(), GL_TEXTURE_EXTERNAL_OES,
+      state_provider_->GetSurfaceTextureId(), picture_buffer_texture_id,
+      state_provider_->GetSize().width(), state_provider_->GetSize().height(),
+      false, false, false, default_matrix);
+}
+
+}  // namespace content