Low framerate during playback with v2.7.6

[noisywan]

Hi folks
I'm having playback issues with Avidemux v2.7.6 on Windows 7 64bit.

The file is a 4K MKV video:
HEVC Main 10@L.5.1
2160p, 24fps, 14M bit/s
DTS 6 chn audio

Video frame rate drops to half speed (~10fps) in Avidemux playback while audio playbacks normal.

Display is in DXVA2 mode
`Decode video using DXVA2` is enabled in HW Accel menu.
`Enable all SIMD` is checked

Same video playbacks fine in VirtualDub2 and MPC-HC

Any suggestions to fix this issue?
Thanks in advance

[eumagga0x2a]

Please provide admlog.txt (%localappdata%\avidemux\admlog.txt) from loading the file.

A considerable slowdown can originate from copying decoded picture data from the hardware video decoder in the graphics card to the main memory and back to the graphics card for display.

[noisywan]

Here is the log file.
You cannot view this attachment.

[eumagga0x2a]

A quote from the log:

Code Select Expand

Probing for DXVA2...
[admD3D_initD3D9Ex] 20:39:31-147 Probing for D3D9EX support
[admD3D_initD3D9Ex] 20:39:31-157 D3D library loaded in D3D9Ex mode, Checking Adapater display mode
[admD3D_initD3D9Ex] 20:39:31-157 Display is 1920 x 1080, fmt=0x16
[admD3D_initD3D9Ex] 20:39:31-157 D3D Device: AMD Radeon HD 5800 Series, Vendor: 1002, Device: 689e, Rev: 0, Driver Version: 2251872828786044
[admD3D_initD3D9Ex] 20:39:31-157 Creating Device9EX
[admD3D_initD3D9Ex] 20:39:31-182 D3D:d3d9Ex core successfully initialized
[admDxva2::init] 20:39:31-182 Dxva2 init step1
[admDxva2::init] 20:39:31-182 Dxva2 core successfully initialized
[admDxva2::init] 20:39:31-182 Decoder service=00000000005495F8
Potential device_guid :
0x1b81be69 0xa0c7 0x11d3  b9  84  00  c0  4f  2e  73  c5
Potential device_guid :
0x1b81be68 0xa0c7 0x11d3  b9  84  00  c0  4f  2e  73  c5
[checkDecoderConfiguration] 20:39:31-183 has h264 raw bistream2
[checkDecoderConfiguration] 20:39:31-183 has no encrypt
[checkDecoderConfiguration] 20:39:31-183 best score
[checkDecoderConfiguration] 20:39:31-183 has h264 raw bistream2
[checkDecoderConfiguration] 20:39:31-183 has no encrypt
[checkDecoderConfiguration] 20:39:31-183 has h264 raw bistream2
[lookupCodec] 20:39:31-183 DXVA2 support for  H264 found
Potential device_guid :
0x5b11d51b 0x2f4c 0x4452  bc  c3  09  f2  a1  16  0c  c0
Potential device_guid :
0x107af0e0 0xef1a 0x4d19  ab  a8  67  a1  63  07  3d  13
[lookupCodec] 20:39:31-183 No decoder device for codec H265 found
Potential device_guid :
0x5b11d51b 0x2f4c 0x4452  bc  c3  09  f2  a1  16  0c  c0
Potential device_guid :
0x107af0e0 0xef1a 0x4d19  ab  a8  67  a1  63  07  3d  13
[lookupCodec] 20:39:31-183 No decoder device for codec H265 found
[admDxva2::init] 20:39:31-183 Scanning supported format done
This graphics card (UVD 2.2) has no decoding support for HEVC (available from UVD 6 on), the CPU is doing all the decoding work. No idea what VirtualDub2 and MPC-HC are doing to achieve real-time decoding. Maybe they are dropping (a lot of) frames.

[noisywan]

Thank you for the diagnosis. Looks like HEVC without a decent GFX card won't let me edit 4K in Avidemux.

I must correct something that I overlooked about VirtualDub2 previously. It does NOT playback at realtime, but it's close. (about 3/4 speed)

The MPC-HC `feels` like it's realtime, I don't see any drops but I can't be %100 sure about that.