DXVA: Add --disable-low-latency-dxva to disable low latency decoding

media/gpu/dxva_video_decode_accelerator_win.cc

 // Copyright (c) 2012 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 "media/gpu/dxva_video_decode_accelerator_win.h"
 
 #include <memory>
 
 #if !defined(OS_WIN)
 #error This file should only be built on Windows.
@@ skipping 483 matching lines @@
       egl_config_(NULL),
       state_(kUninitialized),
       pictures_requested_(false),
       inputs_before_decode_(0),
       sent_drain_message_(false),
       get_gl_context_cb_(get_gl_context_cb),
       make_context_current_cb_(make_context_current_cb),
       codec_(kUnknownVideoCodec),
       decoder_thread_("DXVAVideoDecoderThread"),
       pending_flush_(false),
+      enable_low_latency_(gpu_preferences.enable_low_latency_dxva),
       share_nv12_textures_(gpu_preferences.enable_zero_copy_dxgi_video &&
                            !workarounds.disable_dxgi_zero_copy_video),
       copy_nv12_textures_(gpu_preferences.enable_nv12_dxgi_video &&
                           !workarounds.disable_nv12_dxgi_video),
       use_dx11_(false),
       use_keyed_mutex_(false),
       dx11_video_format_converter_media_type_needs_init_(true),
       using_angle_device_(false),
       enable_accelerated_vpx_decode_(
           gpu_preferences.enable_accelerated_vpx_decode),
@@ skipping 933 matching lines @@
 
   UINT32 dxva = 0;
   hr = attributes->GetUINT32(MF_SA_D3D_AWARE, &dxva);
   RETURN_ON_HR_FAILURE(hr, "Failed to check if decoder supports DXVA", false);
 
   if (codec_ == kCodecH264) {
     hr = attributes->SetUINT32(CODECAPI_AVDecVideoAcceleration_H264, TRUE);
     RETURN_ON_HR_FAILURE(hr, "Failed to enable DXVA H/W decoding", false);
   }
 
-  hr = attributes->SetUINT32(CODECAPI_AVLowLatencyMode, TRUE);
-  if (SUCCEEDED(hr)) {
-    DVLOG(1) << "Successfully set Low latency mode on decoder.";
-  } else {
-    DVLOG(1) << "Failed to set Low latency mode on decoder. Error: " << hr;
+  if (enable_low_latency_) {
+    hr = attributes->SetUINT32(CODECAPI_AVLowLatencyMode, TRUE);
+    if (SUCCEEDED(hr)) {
+      DVLOG(1) << "Successfully set Low latency mode on decoder.";
+    } else {
+      DVLOG(1) << "Failed to set Low latency mode on decoder. Error: " << hr;
+    }
   }
 
   auto* gl_context = get_gl_context_cb_.Run();
   RETURN_ON_FAILURE(gl_context, "Couldn't get GL context", false);
 
   // The decoder should use DX11 iff
   // 1. The underlying H/W decoder supports it.
   // 2. We have a pointer to the MFCreateDXGIDeviceManager function needed for
   //    this. This should always be true for Windows 8+.
   // 3. ANGLE is using DX11.
@@ skipping 1237 matching lines @@
   SetState(kConfigChange);
   Invalidate();
   Initialize(config_, client_);
   decoder_thread_task_runner_->PostTask(
       FROM_HERE,
       base::Bind(&DXVAVideoDecodeAccelerator::DecodePendingInputBuffers,
                  base::Unretained(this)));
 }
 
 }  // namespace media