Chromium代码：实现GPU->GPU的直接图片传递，不需要通过CPU进行中转

优化GPU视频到2D画布复制流程，提升性能与电池寿命

最新推荐文章于 2024-03-21 09:41:13 发布

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#webview #硬件加速 #gpu #chromium #android

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此提交优化了在渲染加速2D画布上绘制GPU解码视频的流程，通过引入缓存机制，使得GPU到GPU的直接复制成为可能，从而显著提高了速度并节省了电池电量。此外，该更改还修复了Android平台上的视频背景显示问题，并确保了跨平台的黑色背景绘制效果。实现了对视频帧纹理的直接复制至GPU纹理，减少了中间内存复制步骤，进一步提升了整体效率。

commit0c4e9d8781aea6e52fdb4a7aee978817910c67ea
authordongseong.hwang Thu Jan 08 20:11:13 2015
committerCommit bot Thu Jan 08 20:12:02 2015

media: Optimize HW Video to 2D Canvas copy.

Currently, when we draws GPU decoded Video on accelerated 2D Canvas, chromium
reads back pixel from GPU and then uploads the pixel to GPU to make a SkBitmap.
It's so inefficient for both speed and battery. On the other hand, only Android
copies GPU-GPU in this case, but Android doesn't have cache mechanism which
SkCanvasVideoRenderer provides.

This CL makes all platforms copy gpu-gpu with cache mechanism. Cache mechanism
is useful when 2d canvas draws a video frame many times.
e.g. http://craftymind.com/factory/html5video/CanvasVideo.html

In addition, fix white video background on Android when not loaded. Other platforms
draw black background thanks to SkCanvasVideoRenderer::Paint().

In detail of the changes;
1. Implement gpu-gpu copy in SkCanvasVideoRenderer::Paint() like previous
WebMediaPlayerAndroid::paint().
2. Move duplicated GPU code on WebMediaPlayerImpl and WebMediaPlayerAndroid to
SkCanvasVideoRenderer.

Perf data on i5 IvyBridge
blink_perf.all:Canvas_draw-video-to-hw-accelerated-canvas-2d
15.8x speed up: 116.27 runs/s -> 1847.23 runs/s
NOTE: measure after disabling cache in SkCanvasVideoRenderer

BUG=401058, 263667

Review URL: https://codereview.chromium.org/445013002

Cr-Commit-Position: refs/heads/master@{#310577}

从视频复制到图片，GPU到GPU直接传递，不需要经过CPU内存？

// static
void SkCanvasVideoRenderer::CopyVideoFrameTextureToGLTexture(
    gpu::gles2::GLES2Interface* gl,
    VideoFrame* video_frame,
    unsigned int texture,
    unsigned int level,
    unsigned int internal_format,
    unsigned int type,
    bool premultiply_alpha,
    bool flip_y) {
  DCHECK(video_frame && video_frame->format() == VideoFrame::NATIVE_TEXTURE);
  const gpu::MailboxHolder* mailbox_holder = video_frame->mailbox_holder();
  DCHECK(mailbox_holder->texture_target == GL_TEXTURE_2D ||
         mailbox_holder->texture_target == GL_TEXTURE_EXTERNAL_OES);
  gl->WaitSyncPointCHROMIUM(mailbox_holder->sync_point);
  uint32 source_texture = gl->CreateAndConsumeTextureCHROMIUM(
      mailbox_holder->texture_target, mailbox_holder->mailbox.name);
  // The video is stored in a unmultiplied format, so premultiply
  // if necessary.
  gl->PixelStorei(GL_UNPACK_PREMULTIPLY_ALPHA_CHROMIUM, premultiply_alpha);
  // Application itself needs to take care of setting the right |flip_y|
  // value down to get the expected result.
  // "flip_y == true" means to reverse the video orientation while
  // "flip_y == false" means to keep the intrinsic orientation.
  gl->PixelStorei(GL_UNPACK_FLIP_Y_CHROMIUM, flip_y);
  gl->CopyTextureCHROMIUM(GL_TEXTURE_2D, source_texture, texture, level,
                          internal_format, type);
  gl->PixelStorei(GL_UNPACK_FLIP_Y_CHROMIUM, false);
  gl->PixelStorei(GL_UNPACK_PREMULTIPLY_ALPHA_CHROMIUM, false);
  gl->DeleteTextures(1, &source_texture);
  gl->Flush();
  SyncPointClientImpl client(gl);
  video_frame->UpdateReleaseSyncPoint(&client);
}