UserAgent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/52.0.2743.116 Safari/537.36 Edge/15.15063

Example URL:
https://www.youtube.com/watch?v=6BfGONXVToA

Steps to reproduce the problem:
1. Go to the video referenced with HW acceleration enabled

What is the expected behavior?
For the playback to fallback to software acceleration without having to specify the --disable-accelerated-video-decode flag

What went wrong?
Could be something in diff# 638337f / diff #45c6a9b .  Chrome debug log shows the following:  NOT IMPLEMENTED
[308:768:0207/185229.399:ERROR:video_resource_updater.cc(782)]

I looked through all the code leading to this and there are a couple of issues.  I'm just going to paste in my notes from our internal ticketing here for you.  Should give you a few options I saw depending on what the internals actually do:

----
Looks like falling through.  Guessing 782 is line number since seems to align with the not implemented in the switch:

https://cs.chromium.org/chromium/src/cc/resources/video_resource_updater.cc?type=cs&sq=package:chromium&l=782

Version history shows some changes in this area.  Variable names / history indicate color space, texture, or buffer issue of some form.
---
This resolves issue other than fully disabling GPU acceleration (which probably just includes this switch internally):  "C:\Program Files (x86)\Google\Chrome\Application\chrome.exe" "https://www.youtube.com/watch?v=6BfGONXVToA" --disable-accelerated-video-decode

Based on the chrome://gpu result, this will disable HW acceleration only for video decoding.  May be some other setting that can more granularly be set, but unknown, would need to further go through source to find

https://cs.chromium.org/chromium/src/content/public/common/web_preferences.h?sq=package:chromium&type=cs&l=203
https://cs.chromium.org/chromium/src/ppapi/shared_impl/ppapi_preferences.h?sq=package:chromium&type=cs&l=33
The disable switch ends up setting this to zero:  https://cs.chromium.org/chromium/src/ppapi/proxy/ppb_video_decoder_proxy.cc?sq=package:chromium&type=cs&l=197
Leading to issue being in location where CreateProxyResource() is returned:  https://cs.chromium.org/chromium/src/ppapi/proxy/ppb_video_decoder_proxy.cc?sq=package:chromium&type=cs&l=187
So, the root function call ultimate fails to match external_resources.type (https://cs.chromium.org/chromium/src/cc/resources/video_resource_updater.cc?type=cs&sq=package:chromium&l=583), which is returned by Then the type on external_resources https://cs.chromium.org/chromium/src/cc/resources/video_resource_updater.cc?type=cs&sq=package:chromium&l=583 falls through in the switch

The effected videos should be where one of these get hit starting in https://cs.chromium.org/chromium/src/cc/resources/video_resource_updater.cc?type=cs&sq=package:chromium&l=281:
The pixel format is unknown for the video per: 
 https://cs.chromium.org/chromium/src/cc/resources/video_resource_updater.cc?type=cs&sq=package:chromium&l=284
There is no "context_provider_" per: 
 https://cs.chromium.org/chromium/src/cc/resources/video_resource_updater.cc?type=cs&sq=package:chromium&l=856
(unknown if this is what is occurring, chrome log did not have "unsupported texture format" anywhere)The pixel format is not in their switch at all, or is one of the formats that falls through to the break (has no default error, so falls through with default value of pixel format unknown):  https://cs.chromium.org/chromium/src/cc/resources/video_resource_updater.cc?type=cs&sq=package:chromium&l=39

Assuming their expected fallback behavior is to switch to SW decoding if HW decoding fails (probably since the master setting for GPU is "Use hardware acceleration when available")

Seems like they may want to do something instead like toggle over to software instead of hardware (unless hardware is forced / software is disabledwith command-line switch) if these conditions are true when https://cs.chromium.org/chromium/src/cc/resources/video_resource_updater.cc?type=cs&sq=package:chromium&l=39 is called, :  from at least the path on https://cs.chromium.org/chromium/src/cc/resources/video_resource_updater.cc?type=cs&sq=package:chromium&l=287 explicitly dealing with only HW acceleration being attempted at that point.  May want to cache result of that HW acceleration failure if the failure occurring is an expensive calculation or not with few additional bool checks against some static toggle to go straight to SW -- assuming all frames part of the series would hit the same issue (ie:  some one-off frame couldn't result in this behavior occurring and toggle the rest of the stream to software even if they would otherwise evaluate correctly for hardware).  Would be good to have message displayed to user (even if have to enable it via registry or something, but could display default and have a "do not show again" sort of option) 

Did this work before? Yes 63 - < 64

Is it a problem with Flash or HTML5? HTML5

Does this work in other browsers? Yes

Chrome version: 64+  Channel: n/a
OS Version: 10.0
Flash Version: 

Contents of chrome://gpu: 
Note: To properly save this page, select the "Webpage, Complete" option in the Save File dialog.
Graphics Feature Status
Canvas: Hardware accelerated
CheckerImaging: Disabled
Flash: Hardware accelerated
Flash Stage3D: Hardware accelerated
Flash Stage3D Baseline profile: Hardware accelerated
Compositing: Hardware accelerated
Multiple Raster Threads: Disabled
Native GpuMemoryBuffers: Software only. Hardware acceleration disabled
Rasterization: Software only, hardware acceleration unavailable
Video Decode: Hardware accelerated
WebGL: Hardware accelerated
WebGL2: Hardware accelerated
Driver Bug Workarounds
clear_uniforms_before_first_program_use
decode_encode_srgb_for_generatemipmap
disable_accelerated_vpx_decode
disable_discard_framebuffer
disable_dxgi_zero_copy_video
disable_framebuffer_cmaa
disable_nv12_dxgi_video
exit_on_context_lost
force_cube_complete
scalarize_vec_and_mat_constructor_args
texsubimage_faster_than_teximage
Problems Detected
GPU rasterization should only be enabled on NVIDIA and Intel DX11+, and AMD RX-R2 GPUs for now.: 643850
Disabled Features: gpu_rasterization
Some drivers are unable to reset the D3D device in the GPU process sandbox
Applied Workarounds: exit_on_context_lost
TexSubImage is faster for full uploads on ANGLE
Applied Workarounds: texsubimage_faster_than_teximage
Clear uniforms before first program use on all platforms: 124764, 349137
Applied Workarounds: clear_uniforms_before_first_program_use
Always rewrite vec/mat constructors to be consistent: 398694
Applied Workarounds: scalarize_vec_and_mat_constructor_args
ANGLE crash on glReadPixels from incomplete cube map texture: 518889
Applied Workarounds: force_cube_complete
Framebuffer discarding can hurt performance on non-tilers: 570897
Applied Workarounds: disable_discard_framebuffer
Use GL_INTEL_framebuffer_CMAA on ChromeOS: 535198
Applied Workarounds: disable_framebuffer_cmaa
Disable KHR_blend_equation_advanced until cc shaders are updated: 661715
Applied Workarounds: disable(GL_KHR_blend_equation_advanced), disable(GL_KHR_blend_equation_advanced_coherent)
Decode and Encode before generateMipmap for srgb format textures on Windows: 634519
Applied Workarounds: decode_encode_srgb_for_generatemipmap
Zero-copy DXGI video hangs or displays incorrect colors on AMD drivers: 623029
Applied Workarounds: disable_dxgi_zero_copy_video
NV12 DXGI video displays incorrect colors on older AMD drivers: 644293
Applied Workarounds: disable_nv12_dxgi_video
VPx decoding isn't supported well before Windows 10 creators update.: 616318, 667532
Applied Workarounds: disable_accelerated_vpx_decode
Raster is using a single thread.
Disabled Features: multiple_raster_threads
Native GpuMemoryBuffers have been disabled, either via about:flags or command line.
Disabled Features: native_gpu_memory_buffers
Checker-imaging has been disabled via finch trial or the command line.
Disabled Features: checker_imaging
Version Information
Data exported	2/7/2018, 7:51:50 PM
Chrome version	Chrome/64.0.3282.140
Operating system	Windows NT 10.0.10240
Software rendering list URL	https://chromium.googlesource.com/chromium/src/+/a06bc1d5e8e285c70078802de990c1719ccc75e8/gpu/config/software_rendering_list.json
Driver bug list URL	https://chromium.googlesource.com/chromium/src/+/a06bc1d5e8e285c70078802de990c1719ccc75e8/gpu/config/gpu_driver_bug_list.json
ANGLE commit id	2987f0fde973
2D graphics backend	Skia/64 713571f9afcf4b673812cd3b52bb5b17c107038b-
Command Line	"C:\Program Files (x86)\Google\Chrome\Application\chrome.exe" --flag-switches-begin --flag-switches-end
Driver Information
Initialization time	224
In-process GPU	false
Passthrough Command Decoder	false
Supports overlays	false
Sandboxed	false
GPU0	VENDOR = 0x1002, DEVICE= 0x9710
Optimus	false
Optimus	false
AMD switchable	false
Desktop compositing	Aero Glass
Driver vendor	Advanced Micro Devices, Inc.
Driver version	8.970.100.9001
Driver date	1-13-2015
Pixel shader version	4.1
Vertex shader version	4.1
Max. MSAA samples	4
Machine model name	
Machine model version	
GL_VENDOR	Google Inc.
GL_RENDERER	ANGLE (ATI Radeon HD 4200 Direct3D11 vs_4_1 ps_4_1)
GL_VERSION	OpenGL ES 3.0 (ANGLE 2.1.0.2987f0fde973)
GL_EXTENSIONS	GL_ANGLE_client_arrays GL_ANGLE_depth_texture GL_ANGLE_framebuffer_blit GL_ANGLE_framebuffer_multisample GL_ANGLE_instanced_arrays GL_ANGLE_lossy_etc_decode GL_ANGLE_pack_reverse_row_order GL_ANGLE_program_cache_control GL_ANGLE_request_extension GL_ANGLE_robust_client_memory GL_ANGLE_texture_compression_dxt3 GL_ANGLE_texture_compression_dxt5 GL_ANGLE_texture_usage GL_ANGLE_translated_shader_source GL_CHROMIUM_bind_generates_resource GL_CHROMIUM_bind_uniform_location GL_CHROMIUM_color_buffer_float_rgb GL_CHROMIUM_color_buffer_float_rgba GL_CHROMIUM_copy_compressed_texture GL_CHROMIUM_copy_texture GL_CHROMIUM_sync_query GL_EXT_blend_minmax GL_EXT_color_buffer_float GL_EXT_color_buffer_half_float GL_EXT_debug_marker GL_EXT_discard_framebuffer GL_EXT_disjoint_timer_query GL_EXT_draw_buffers GL_EXT_frag_depth GL_EXT_map_buffer_range GL_EXT_occlusion_query_boolean GL_EXT_read_format_bgra GL_EXT_robustness GL_EXT_sRGB GL_EXT_shader_texture_lod GL_EXT_texture_compression_dxt1 GL_EXT_texture_compression_s3tc_srgb GL_EXT_texture_filter_anisotropic GL_EXT_texture_format_BGRA8888 GL_EXT_texture_norm16 GL_EXT_texture_rg GL_EXT_texture_storage GL_EXT_unpack_subimage GL_KHR_debug GL_NV_EGL_stream_consumer_external GL_NV_fence GL_NV_pack_subimage GL_NV_pixel_buffer_object GL_OES_EGL_image GL_OES_EGL_image_external GL_OES_EGL_image_external_essl3 GL_OES_compressed_ETC1_RGB8_texture GL_OES_depth32 GL_OES_element_index_uint GL_OES_get_program_binary GL_OES_mapbuffer GL_OES_packed_depth_stencil GL_OES_rgb8_rgba8 GL_OES_standard_derivatives GL_OES_surfaceless_context GL_OES_texture_float GL_OES_texture_float_linear GL_OES_texture_half_float GL_OES_texture_half_float_linear GL_OES_texture_npot GL_OES_vertex_array_object
Disabled Extensions	GL_KHR_blend_equation_advanced GL_KHR_blend_equation_advanced_coherent
Window system binding vendor	Google Inc. (adapter LUID: 0000000000005993)
Window system binding version	1.4 (ANGLE 2.1.0.2987f0fde973)
Window system binding extensions	EGL_EXT_create_context_robustness EGL_ANGLE_d3d_share_handle_client_buffer EGL_ANGLE_d3d_texture_client_buffer EGL_ANGLE_surface_d3d_texture_2d_share_handle EGL_ANGLE_query_surface_pointer EGL_ANGLE_window_fixed_size EGL_ANGLE_keyed_mutex EGL_ANGLE_surface_orientation EGL_ANGLE_direct_composition EGL_NV_post_sub_buffer EGL_KHR_create_context EGL_EXT_device_query EGL_KHR_image EGL_KHR_image_base EGL_KHR_gl_texture_2D_image EGL_KHR_gl_texture_cubemap_image EGL_KHR_gl_renderbuffer_image EGL_KHR_get_all_proc_addresses EGL_KHR_stream EGL_KHR_stream_consumer_gltexture EGL_NV_stream_consumer_gltexture_yuv EGL_ANGLE_flexible_surface_compatibility EGL_ANGLE_create_context_webgl_compatibility EGL_CHROMIUM_create_context_bind_generates_resource EGL_CHROMIUM_sync_control EGL_EXT_pixel_format_float EGL_KHR_surfaceless_context EGL_ANGLE_display_texture_share_group EGL_ANGLE_create_context_client_arrays EGL_ANGLE_program_cache_control EGL_ANGLE_robust_resource_initialization
Direct rendering	Yes
Reset notification strategy	0x8252
GPU process crash count	0
Compositor Information
Tile Update Mode	One-copy
Partial Raster	Enabled
GpuMemoryBuffers Status
ATC	Software only
ATCIA	Software only
DXT1	Software only
DXT5	Software only
ETC1	Software only
R_8	Software only
R_16	Software only
RG_88	Software only
BGR_565	Software only
RGBA_4444	Software only
RGBX_8888	GPU_READ, SCANOUT
RGBA_8888	GPU_READ, SCANOUT
BGRX_8888	Software only
BGRX_1010102	Software only
BGRA_8888	Software only
RGBA_F16	Software only
YVU_420	Software only
YUV_420_BIPLANAR	Software only
UYVY_422	Software only
Display(s) Information
Info	Display[2528732444] bounds=0,0 1366x768, workarea=0,0 1366x728, scale=1, external
Color space information	{primaries:BT709, transfer:IEC61966_2_1, matrix:RGB, range:FULL}
Bits per color component	8
Bits per pixel	24
Video Acceleration Information
Decode h264 baseline	up to 1920x1088 pixels
Decode h264 main	up to 1920x1088 pixels
Decode h264 high	up to 1920x1088 pixels
Encode h264 baseline	up to 3840x2176 pixels and/or 30.000 fps
Encode h264 main	up to 3840x2176 pixels and/or 30.000 fps
Encode h264 high	up to 3840x2176 pixels and/or 30.000 fps
Diagnostics
0
b3DAccelerationEnabled	true
b3DAccelerationExists	true
bAGPEnabled	true
bAGPExistenceValid	true
bAGPExists	false
bCanRenderWindow	true
bDDAccelerationEnabled	true
bDriverBeta	false
bDriverDebug	false
bDriverSigned	false
bDriverSignedValid	false
bNoHardware	true
dwBpp	32
dwDDIVersion	9
dwHeight	768
dwRefreshRate	32
dwWHQLLevel	0
dwWidth	1366
iAdapter	0
lDriverSize	0
lMiniVddSize	0
szAGPStatusEnglish	Not Available
szAGPStatusLocalized	Not Available
szChipType	
szD3DStatusEnglish	Enabled
szD3DStatusLocalized	Enabled
szDACType	
szDDIVersionEnglish	9Ex
szDDIVersionLocalized	9Ex
szDDStatusEnglish	Not Available
szDDStatusLocalized	Not Available
szDXVAHDEnglish	Not Supported
szDXVAModes	
szDescription	RDPUDD Chained DD
szDeviceId	0x9710
szDeviceIdentifier	{D7B71EE2-D450-11CF-E577-4D10BEC2C535}
szDeviceName	\\.\DISPLAY1
szDisplayMemoryEnglish	n/a
szDisplayMemoryLocalized	n/a
szDisplayModeEnglish	1366 x 768 (32 bit) (32Hz)
szDisplayModeLocalized	1366 x 768 (32 bit) (32Hz)
szDriverAssemblyVersion	
szDriverAttributes	
szDriverDateEnglish	
szDriverDateLocalized	
szDriverLanguageEnglish	
szDriverLanguageLocalized	
szDriverModelEnglish	
szDriverModelLocalized	
szDriverName	
szDriverNodeStrongName	
szDriverSignDate	
szDriverVersion	
szKeyDeviceID	Enum\ROOT\BASICRENDER
szKeyDeviceKey	\REGISTRY\Machine\System\CurrentControlSet\Services\RDPUDD\Device0
szManufacturer	
szMiniVdd	
szMiniVddDateEnglish	
szMiniVddDateLocalized	
szMonitorMaxRes	
szMonitorName	
szNotesEnglish	No problems found.
szNotesLocalized	No problems found.
szOverlayEnglish	Not Supported
szRankOfInstalledDriver	
szRegHelpText	
szRevision	
szRevisionId	0x0000
szSubSysId	0x3047103C
szTestResultD3D7English	Not run
szTestResultD3D7Localized	Not run
szTestResultD3D8English	Not run
szTestResultD3D8Localized	Not run
szTestResultD3D9English	Not run
szTestResultD3D9Localized	Not run
szTestResultDDEnglish	Not run
szTestResultDDLocalized	Not run
szVdd	
szVendorId	0x1002
Log Messages
[1200:2612:0207/195146.800:ERROR:gpu_command_buffer_stub.cc(708)] : ContextResult::kFatalFailure: Failed to create surface.
GpuProcessHostUIShim: The GPU process exited normally. Everything is okay.