我最近更换了 PC，从配备集成显卡的 Intel Core i5 4460 变为配备 AMD RADEON RX 550 显卡的 Xeon E5 2678 v3。
在纸面上，新 PC 的性能是旧 PC 的 3 到 7 倍，我可以证明在日常使用、视频和图像编辑等方面就是这种情况。拥有这么多内核和线程的优势是明显的。在游戏方面我没有尝试过，因为我不是真正的游戏玩家，而且我使用的少数游戏是 Debian 和一些模拟器附带的典型免费游戏，老实说，它们已经在旧 PC 上运行良好。
然而，有一项任务因其糟糕的性能而让我大吃一惊：视频屏幕捕获。
使用我的旧电脑，我能够在执行任何需要录制的任务时以超过 60 fps 的速度全屏拍摄。
即使使用我的联想 thinkpad x230，我也能够以超过 80fps 的速度完全流畅地捕捉屏幕。
我一直使用的命令是：
ffmpeg -f x11grab -draw_mouse 1 -framerate 60 -video_size 1920x1200 -i :0.0+1680,0 -qscale 0 -pix_fmt yuv420p -c:v libx264 -preset medium -qp 0 -q:v 1 -s 1920x1200 -f matroska -threads 4 video.mkv
笔记：
-video_size 1920x1200 -i :0.0+1680,0 y -s 1920x1200 是要捕获的区域的尺寸和位置（我的右显示器）。
请注意，我什至使用了 -preset 媒体和软件编码，因此即使使用该参数设置，我也获得了非常好的质量，并且从未低于 60 fps。
我现在怎么了？
该设备无法捕获超过 20 fps 的视频，这使得任何视频都无效，出现丢帧甚至达不到 30 fps，这将是最低要求。
此外，当我启动命令时，PC 的响应能力下降非常明显。也就是说，正常工作时所欣赏的所有流动性和平滑性都会消失，甚至将窗户从一侧移动到另一侧都是粗糙和绊脚石。
我尝试使用 ffmpeg 的不同参数来捕获原始数据，无需编码。
我尝试将生成的视频直接保存到 RAM 磁盘，以避免写入磁盘可能出现的瓶颈。它根本不影响它。
那么，是否有人对至少我可以在哪里进一步挖掘以找到问题的解决方案有任何建议？
附加数据，以防有帮助：
$ → inxi
CPU: 12-Core Intel Xeon E5-2678 v3 (-MT MCP-)
speed/min/max: 1201/1200/3300 MHz Kernel: 5.10.0-0.bpo.4-amd64 x86_64
Up: 1d 6h 55m Mem: 6427.6/32012.4 MiB (20.1%)
Storage: 13.76 TiB (55.9% used) Procs: 433 Shell: bash 5.0.18 inxi: 3.0.32
$ → ffmpeg -v
ffmpeg version 4.1.6 Copyright (c) 2000-2020 the FFmpeg developers
built with gcc 8 (Debian 8.3.0-6)
configuration: --disable-decoder=amrnb --disable-decoder=libopenjpeg --disable-libopencv --disable-outdev=sdl2 --disable-podpages --disable-sndio --disable-stripping --enable-libaom --enable-avfilter --enable-avresample --enable-gcrypt --disable-gnutls --enable-openssl --enable-gpl --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libcodec2 --enable-libfdk-aac --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libilbc --enable-libkvazaar --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenh264 --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librubberband --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libtesseract --enable-libtheora --enable-libvidstab --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libx265 --enable-libzimg --enable-libxvid --enable-libzvbi --enable-nonfree --enable-opencl --enable-opengl --enable-postproc --enable-pthreads --enable-shared --enable-version3 --enable-libwebp --incdir=/usr/include/x86_64-linux-gnu --libdir=/usr/lib/x86_64-linux-gnu --prefix=/usr --toolchain=hardened --enable-frei0r --enable-chromaprint --enable-libx264 --enable-libiec61883 --enable-libdc1394 --enable-vaapi --enable-libmfx --enable-libvmaf --disable-altivec --shlibdir=/usr/lib/x86_64-linux-gnu
libavutil 56. 22.100 / 56. 22.100
libavcodec 58. 35.100 / 58. 35.100
libavformat 58. 20.100 / 58. 20.100
libavdevice 58. 5.100 / 58. 5.100
libavfilter 7. 40.101 / 7. 40.101
libavresample 4. 0. 0 / 4. 0. 0
libswscale 5. 3.100 / 5. 3.100
libswresample 3. 3.100 / 3. 3.100
libpostproc 55. 3.100 / 55. 3.100
我有免费的 amdgpu 驱动程序（不是 amdgpu-pro），但我激活了 opencl 以防万一。
我遵循了本教程：
https://linuxconfig.org/how-to-install-the-latest-amd-drivers-on-debian-10-buster
$ → glxinfo | grep OpenGL
OpenGL vendor string: AMD
OpenGL renderer string: Radeon RX550/550 Series (POLARIS12, DRM 3.40.0, 5.10.0-0.bpo.4-amd64, LLVM 11.0.1)
OpenGL core profile version string: 4.6 (Core Profile) Mesa 20.3.4
OpenGL core profile shading language version string: 4.60
OpenGL core profile context flags: (none)
OpenGL core profile profile mask: core profile
OpenGL core profile extensions:
OpenGL version string: 4.6 (Compatibility Profile) Mesa 20.3.4
OpenGL shading language version string: 4.60
OpenGL context flags: (none)
OpenGL profile mask: compatibility profile
OpenGL extensions:
OpenGL ES profile version string: OpenGL ES 3.2 Mesa 20.3.4
OpenGL ES profile shading language version string: OpenGL ES GLSL ES 3.20
OpenGL ES profile extensions:
$ → clinfo
Number of platforms 1
Platform Name Clover
Platform Vendor Mesa
Platform Version OpenCL 1.1 Mesa 20.3.4
Platform Profile FULL_PROFILE
Platform Extensions cl_khr_icd
Platform Extensions function suffix MESA
Platform Name Clover
Number of devices 1
Device Name Radeon RX550/550 Series (POLARIS12, DRM 3.40.0, 5.10.0-0.bpo.4-amd64, LLVM 11.0.1)
Device Vendor AMD
Device Vendor ID 0x1002
Device Version OpenCL 1.1 Mesa 20.3.4
Driver Version 20.3.4
Device OpenCL C Version OpenCL C 1.1
Device Type GPU
Device Profile FULL_PROFILE
Device Available Yes
Compiler Available Yes
Max compute units 8
Max clock frequency 1183MHz
Max work item dimensions 3
Max work item sizes 256x256x256
Max work group size 256
Preferred work group size multiple 64
Preferred / native vector sizes
char 16 / 16
short 8 / 8
int 4 / 4
long 2 / 2
half 0 / 0 (n/a)
float 4 / 4
double 2 / 2 (cl_khr_fp64)
Half-precision Floating-point support (n/a)
Single-precision Floating-point support (core)
Denormals No
Infinity and NANs Yes
Round to nearest Yes
Round to zero No
Round to infinity No
IEEE754-2008 fused multiply-add No
Support is emulated in software No
Correctly-rounded divide and sqrt operations No
Double-precision Floating-point support (cl_khr_fp64)
Denormals Yes
Infinity and NANs Yes
Round to nearest Yes
Round to zero Yes
Round to infinity Yes
IEEE754-2008 fused multiply-add Yes
Support is emulated in software No
Address bits 64, Little-Endian
Global memory size 3221225472 (3GiB)
Error Correction support No
Max memory allocation 1717986918 (1.6GiB)
Unified memory for Host and Device No
Minimum alignment for any data type 128 bytes
Alignment of base address 32768 bits (4096 bytes)
Global Memory cache type None
Image support No
Local memory type Local
Local memory size 32768 (32KiB)
Max number of constant args 16
Max constant buffer size 67108864 (64MiB)
Max size of kernel argument 1024
Queue properties
Out-of-order execution No
Profiling Yes
Profiling timer resolution 0ns
Execution capabilities
Run OpenCL kernels Yes
Run native kernels No
Device Extensions cl_khr_byte_addressable_store cl_khr_global_int32_base_atomics cl_khr_global_int32_extended_atomics cl_khr_local_int32_base_atomics cl_khr_local_int32_extended_atomics cl_khr_int64_base_atomics cl_khr_int64_extended_atomics cl_khr_fp64
NULL platform behavior
clGetPlatformInfo(NULL, CL_PLATFORM_NAME, ...) Clover
clGetDeviceIDs(NULL, CL_DEVICE_TYPE_ALL, ...) Success [MESA]
clCreateContext(NULL, ...) [default] Success [MESA]
clCreateContextFromType(NULL, CL_DEVICE_TYPE_DEFAULT) Success (1)
Platform Name Clover
Device Name Radeon RX550/550 Series (POLARIS12, DRM 3.40.0, 5.10.0-0.bpo.4-amd64, LLVM 11.0.1)
clCreateContextFromType(NULL, CL_DEVICE_TYPE_CPU) No devices found in platform
clCreateContextFromType(NULL, CL_DEVICE_TYPE_GPU) Success (1)
Platform Name Clover
Device Name Radeon RX550/550 Series (POLARIS12, DRM 3.40.0, 5.10.0-0.bpo.4-amd64, LLVM 11.0.1)
clCreateContextFromType(NULL, CL_DEVICE_TYPE_ACCELERATOR) No devices found in platform
clCreateContextFromType(NULL, CL_DEVICE_TYPE_CUSTOM) No devices found in platform
clCreateContextFromType(NULL, CL_DEVICE_TYPE_ALL) Success (1)
Platform Name Clover
Device Name Radeon RX550/550 Series (POLARIS12, DRM 3.40.0, 5.10.0-0.bpo.4-amd64, LLVM 11.0.1)
ICD loader properties
ICD loader Name OpenCL ICD Loader
ICD loader Vendor OCL Icd free software
ICD loader Version 2.2.12
ICD loader Profile OpenCL 2.2
这不会是撕裂问题，因为播放视频时看不到撕裂并且启用了 TearFree 驱动程序策略。
$ → xrandr --verbose | grep TearFree
TearFree: on
TearFree: on
TearFree: on
非常比你。;)