16-bit video upload to float: intermediate R16_EXT and copy to float.

media/renderers/skcanvas_video_renderer.cc

Index: media/renderers/skcanvas_video_renderer.cc
diff --git a/media/renderers/skcanvas_video_renderer.cc b/media/renderers/skcanvas_video_renderer.cc
index 1e2e9b21ab1a7e25977f25aeb0a8452a56a533ca..c1dd12e559749bd84d27af82c9c2671b68d5e152 100644
--- a/media/renderers/skcanvas_video_renderer.cc
+++ b/media/renderers/skcanvas_video_renderer.cc
@@ -13,6 +13,7 @@
 #include "cc/paint/paint_flags.h"
 #include "gpu/GLES2/gl2extchromium.h"
 #include "gpu/command_buffer/client/gles2_interface.h"
+#include "gpu/command_buffer/common/capabilities.h"
 #include "gpu/command_buffer/common/mailbox_holder.h"
 #include "media/base/data_buffer.h"
 #include "media/base/video_frame.h"
@@ -622,6 +623,38 @@ bool TexImageHelper(VideoFrame* frame,
   return true;
 }
 
+// Upload the |frame| data to temporary texture of |temp_format|,
+// |temp_internalformat| and |temp_type| and then copy intermediate texture
+// subimage to destination |texture|. The destination |texture| is bound to the
+// |target| before the call.
+void TextureSubImageUsingIntermediate(unsigned target,
+                                      unsigned texture,
+                                      gpu::gles2::GLES2Interface* gl,
+                                      VideoFrame* frame,
+                                      int temp_internalformat,
+                                      unsigned temp_format,
+                                      unsigned temp_type,
+                                      int level,
+                                      int xoffset,
+                                      int yoffset,
+                                      bool flip_y,
+                                      bool premultiply_alpha) {
+  unsigned temp_texture = 0;
+  gl->GenTextures(1, &temp_texture);
+  gl->BindTexture(target, temp_texture);
+  gl->TexParameteri(target, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
+  gl->TexParameteri(target, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
+  gl->TexImage2D(target, 0, temp_internalformat, frame->visible_rect().width(),
+                 frame->visible_rect().height(), 0, temp_format, temp_type,
+                 frame->visible_data(0));
+  gl->BindTexture(target, texture);
+  gl->CopySubTextureCHROMIUM(temp_texture, 0, target, texture, level, 0, 0,
+                             xoffset, yoffset, frame->visible_rect().width(),
+                             frame->visible_rect().height(), flip_y,
+                             premultiply_alpha, false);
+  gl->DeleteTextures(1, &temp_texture);
+}
+
 }  // anonymous namespace
 
 // static
@@ -862,18 +895,43 @@ bool SkCanvasVideoRenderer::CopyVideoFrameTexturesToGLTexture(
   return true;
 }
 
-bool SkCanvasVideoRenderer::TexImage2D(unsigned target,
-                                       gpu::gles2::GLES2Interface* gl,
-                                       VideoFrame* frame,
-                                       int level,
-                                       int internalformat,
-                                       unsigned format,
-                                       unsigned type,
-                                       bool flip_y,
-                                       bool premultiply_alpha) {
+bool SkCanvasVideoRenderer::TexImage2D(
+    unsigned target,
+    unsigned texture,
+    gpu::gles2::GLES2Interface* gl,
+    const gpu::Capabilities& gpu_capabilities,
+    VideoFrame* frame,
+    int level,
+    int internalformat,
+    unsigned format,
+    unsigned type,
+    bool flip_y,
+    bool premultiply_alpha) {
   DCHECK(frame);
   DCHECK(!frame->HasTextures());
 
+  // Note: CopyTextureCHROMIUM uses mediump for color computation. Don't use
+  // it if the precision would lead to data loss when converting 16-bit
+  // normalized to float. medium_float.precision > 15 means that the approach
+  // bellow is not used on Android, where the extension EXT_texture_norm16 is
+  // not widely supported. It is used on Windows, Linux and OSX.

[Ken Russell (switch to Gerrit), 2017/03/31 23:39:30]

EXT_texture_norm16 is supported on recent Qualcomm chipsets and mobile NVIDIA
GPUs. We found it was on the Nexus 5X and Google Pixel phones. See also
http://opengles.gpuinfo.org/gles_listreports.php?extension=GL_EXT_texture_norm16
(though, agreed, only 7.5% coverage). Worth changing CopyTextureCHROMIUM to add
a highp alternative for these devices?

[aleksandar.stojiljkovic, 2017/04/02 11:28:29]

Tested it with highp and it works fine on Adreno 418.

However, I'd like to defer that work until there is a real need - Tango depth
camera support is under work [1] but the Tango depth camera API provides float
values (projected pointcloud).

Don't know yet if there will be a need for highp alternative as part of work on
HDR-10 support [2], but there is no real use case yet to justify the change in
gles2_cmd_copy_texture_chromium.cc[3].

[1] Tango support: crbug.com/674440
[2] HDR-10 related patch crrev.com/2122573003
[3]
https://cs.chromium.org/chromium/src/gpu/command_buffer/service/gles2_cmd_cop...

+  if (gpu_capabilities.texture_norm16 &&
+      gpu_capabilities.fragment_shader_precisions.medium_float.precision > 15 &&
+      target == GL_TEXTURE_2D &&
+      (type == GL_FLOAT || type == GL_UNSIGNED_BYTE)) {
+    // TODO(aleksandar.stojiljkovic): Extend the approach to TexSubImage2D
+    // implementation and other types. See https://crbug.com/624436.
+
+    // Allocate the destination texture.
+    gl->TexImage2D(target, level, internalformat, frame->visible_rect().width(),
+                   frame->visible_rect().height(), 0, format, type, nullptr);
+    // We use sized internal format (0x822A) instead of GL_RED.
+    // See angleproject:1952
+    TextureSubImageUsingIntermediate(
+        target, texture, gl, frame, 0x822A /*GL_R16_EXT*/, GL_RED,

[hubbe, 2017/03/31 17:05:27]

I think we need to add GL_R16_EXT to the right header files..

[aleksandar.stojiljkovic, 2017/04/02 11:28:29]

Done.

+        GL_UNSIGNED_SHORT, level, 0, 0, flip_y, premultiply_alpha);
+    return true;
+  }
   scoped_refptr<DataBuffer> temp_buffer;
   if (!TexImageHelper(frame, format, type, flip_y, &temp_buffer))
     return false;