Add accelerated video decoder interface, VP8 and H.264 implementations and hook up to V4L2SVDA.

content/common/gpu/media/vp8_decoder.cc

+// Copyright 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/vp8_decoder.h"
+#include "media/base/limits.h"
+
+namespace content {
+
+VP8Decoder::VP8Decoder(VP8Accelerator* accelerator)
+    : state_(kNeedStreamMetadata),
+      curr_frame_start_(nullptr),
+      frame_size_(0),
+      accelerator_(accelerator) {
+  DCHECK(accelerator_);
+}
+
+VP8Decoder::~VP8Decoder() {
+}
+
+bool VP8Decoder::Flush() {
+  DVLOG(2) << "Decoder flush";
+  Reset();
+  return true;
+}
+
+void VP8Decoder::SetStream(const uint8_t* ptr, size_t size) {
+  DCHECK(ptr);
+  DCHECK(size);
+
+  curr_frame_start_ = ptr;
+  frame_size_ = size;
+  DVLOG(4) << "New input stream at: " << (void*)ptr << " size: " << size;
+}
+
+void VP8Decoder::Reset() {
+  curr_pic_ = nullptr;
+  curr_frame_hdr_ = nullptr;
+  curr_frame_start_ = nullptr;
+  frame_size_ = 0;
+
+  last_frame_ = nullptr;
+  golden_frame_ = nullptr;
+  alt_frame_ = nullptr;
+
+  if (state_ == kDecoding)
+    state_ = kAfterReset;
+}
+
+VP8Decoder::DecResult VP8Decoder::Decode() {
+  if (!curr_frame_start_ || frame_size_ == 0)
+    return kRanOutOfStreamData;
+
+  if (!curr_frame_hdr_) {
+    curr_frame_hdr_.reset(new media::VP8FrameHeader());
+    if (!parser_.ParseFrame(curr_frame_start_, frame_size_,
+                            curr_frame_hdr_.get())) {
+      DVLOG(1) << "Error during decode";
+      state_ = kError;
+      return VP8Decoder::kDecodeError;

[kcwu, 2015/01/09 10:07:48]

Maybe it is just not enough data, not really error.

[Pawel Osciak, 2015/01/09 13:50:31]

This would indicate a partial frame (since frame_size_ > 0) and we don't allow
that.

+    }
+  }
+
+  if (curr_frame_hdr_->IsKeyframe()) {
+    gfx::Size new_pic_size(curr_frame_hdr_->width, curr_frame_hdr_->height);
+    if (new_pic_size.IsEmpty())
+      return kDecodeError;
+
+    if (pic_size_.IsEmpty() || new_pic_size != pic_size_) {

[Owen Lin, 2015/01/09 09:56:14]

Do we need to test pic_size_.IsEmpty() ?

Since new_pic_size won't be empty, the above check seems redundant. 

[kcwu, 2015/01/09 10:07:48]

"new_pic_size != pic_size_" is enough.

[Pawel Osciak, 2015/01/12 07:18:19]

Done.

[Pawel Osciak, 2015/01/12 07:18:19]

Done.

+      DVLOG(2) << "New resolution: " << new_pic_size.ToString();
+      pic_size_ = new_pic_size;
+      return kAllocateNewSurfaces;
+    }
+
+    state_ = kDecoding;
+  } else {
+    if (state_ != kDecoding) {
+      // Need a resume point.
+      curr_frame_hdr_.reset();
+      return kRanOutOfStreamData;
+    }
+  }
+
+  curr_pic_ = accelerator_->CreateVP8Picture();
+  if (!curr_pic_)
+    return kRanOutOfSurfaces;
+
+  if (!DecodeAndOutputCurrentFrame())
+    return kDecodeError;
+
+  return kRanOutOfStreamData;

[kcwu, 2015/01/09 10:07:48]

IIUC, you only decoded one frame and there may be still enough stream data
remain, right?

[Pawel Osciak, 2015/01/09 13:50:31]

Hm, true, it doesn't happen now since Chrome segments into frames always... I
should loop though anyway to keep this universal as intended.

[Pawel Osciak, 2015/01/12 07:18:19]

Actually, this would apply to H264, but for VP8 we have no way of knowing what
is the frame size from the raw stream, we must get it from the client, so we
can't use any remaining data.

+}
+
+void VP8Decoder::RefreshReferenceFrames() {
+  if (curr_frame_hdr_->IsKeyframe()) {
+    last_frame_ = curr_pic_;
+    golden_frame_ = curr_pic_;
+    alt_frame_ = curr_pic_;
+    return;
+  }
+
+  // Save current golden since we overwrite it here,
+  // but may have to use it to update alt below.
+  scoped_refptr<VP8Picture> curr_golden = golden_frame_;
+
+  if (curr_frame_hdr_->refresh_golden_frame) {
+    golden_frame_ = curr_pic_;
+  } else {
+    switch (curr_frame_hdr_->copy_buffer_to_golden) {
+      case media::VP8FrameHeader::kCopyLastToGolden:
+        DCHECK(last_frame_);

[Owen Lin, 2015/01/09 09:56:14]

Why it is not a decode error? I mean a bad stream should not crash chrome.

[Pawel Osciak, 2015/01/09 13:50:31]

Ah good point.

[Pawel Osciak, 2015/01/12 07:18:19]

Well, actually, recalling my original line of thought, it can't happen unless we
have a bug. Either it's a key frame, so we set all three references, or it's not
and we replace them. We never drop them, unless it's a key frame.

+        golden_frame_ = last_frame_;
+        break;
+
+      case media::VP8FrameHeader::kCopyAltToGolden:
+        DCHECK(alt_frame_);

[Owen Lin, 2015/01/09 09:56:14]

Same here.

[Pawel Osciak, 2015/01/12 07:18:19]

As above.

+        golden_frame_ = alt_frame_;
+        break;
+    }
+  }
+
+  if (curr_frame_hdr_->refresh_alternate_frame) {
+    alt_frame_ = curr_pic_;
+  } else {
+    switch (curr_frame_hdr_->copy_buffer_to_alternate) {
+      case media::VP8FrameHeader::kCopyLastToAlt:
+        DCHECK(last_frame_);
+        alt_frame_ = last_frame_;
+        break;
+
+      case media::VP8FrameHeader::kCopyGoldenToAlt:
+        DCHECK(curr_golden);
+        alt_frame_ = curr_golden;
+        break;
+    }
+  }
+
+  if (curr_frame_hdr_->refresh_last)
+    last_frame_ = curr_pic_;
+}
+
+void VP8Decoder::BeginFrame() {
+  if (curr_frame_hdr_->IsKeyframe()) {
+    horizontal_scale_ = curr_frame_hdr_->horizontal_scale;
+    vertical_scale_ = curr_frame_hdr_->vertical_scale;
+  } else {
+    // Populate fields from decoder state instead.
+    curr_frame_hdr_->width = pic_size_.width();
+    curr_frame_hdr_->height = pic_size_.height();
+    curr_frame_hdr_->horizontal_scale = horizontal_scale_;
+    curr_frame_hdr_->vertical_scale = vertical_scale_;
+  }
+}
+
+bool VP8Decoder::DecodeAndOutputCurrentFrame() {
+  DCHECK(!pic_size_.IsEmpty());
+  DCHECK(curr_pic_);
+  DCHECK(curr_frame_hdr_);
+
+  BeginFrame();

[Owen Lin, 2015/01/09 09:56:14]

[optional] I am kind of thinking there is no need to extract BiginFrame() as an
extra function. It is not so complicated.

[Pawel Osciak, 2015/01/12 07:18:19]

Done.

+
+  if (!accelerator_->SubmitDecode(curr_pic_, curr_frame_hdr_.get(), last_frame_,
+                                  golden_frame_, alt_frame_))
+    return false;
+
+  if (!accelerator_->OutputPicture(curr_pic_))
+    return false;
+
+  RefreshReferenceFrames();
+
+  curr_pic_ = nullptr;
+  curr_frame_hdr_ = nullptr;
+  curr_frame_start_ = nullptr;
+  frame_size_ = 0;

[kcwu, 2015/01/09 10:07:48]

maybe some data still remain after current frame?

[Pawel Osciak, 2015/01/12 07:18:19]

Actually we can't use it, since we must be given frame size from outside, we
have no way to get the size from the stream itself (there is no container in
what we get).

+  return true;
+}
+
+size_t VP8Decoder::GetRequiredNumOfPictures() {
+  static const size_t kVP8NumFramesActive = 4;

[kcwu, 2015/01/09 10:07:48]

no need "static"

[Pawel Osciak, 2015/01/12 07:18:19]

Done.

+  static const size_t kPicsInPipeline = media::limits::kMaxVideoFrames + 2;

[Owen Lin, 2015/01/09 09:56:14]

remove static

[Pawel Osciak, 2015/01/12 07:18:19]

Done.

+  return kVP8NumFramesActive + kPicsInPipeline;
+}
+
+}  // namespace content