最近在Linux下使用ffmpeg收录UDP流花屏问题，发现机器有双网卡，添加路由指定网卡收录导致无法收录了。另附一些解决花屏的优化方法。
cat /etc/sysctl.conf
net.ipv4.conf.default.rp_filter = 0
net.ipv4.conf.all.rp_filter = 0
# 修改默认网络的缓存大小 这个很重要不然
net.core.rmem_max = 50000000
net.core.rmem_default = 50000000
sysctl -p
# 添加以上配置后需要重启系统
reboot
# 不重启的话一定要执行以下命令
for i in /proc/sys/net/ipv4/conf/*/rp_filter ; do echo 0 > "$i"; done
由于博主只修改了上面的 sysctl.conf 并且只执行了 sysctl -p 所以悲剧了，添加路由之后一直无法收录。
route命令参数详细说明及常用命令
原文地址 docs.lvrui.io
> route
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
default localhost 0.0.0.0 UG 100 0 0 eno16780032
172.17.0.0 0.0.0.0 255.255.0.0 U 0 0 0 docker0
192.168.10.0 0.0.0.0 255.255.255.0 U 100 0 0 eno16780032
macOS 中使用 netstat -nr 命令来查看当前路由表
重置macos的Lauchpad(启动台)，及设置Lauchpad(启动台)的行数和列数。
打开终端程序，按需求执行以下命令即可。
defaults write com.apple.dock ResetLaunchPad -bool TRUE;
killall Dock
defaults write com.apple.dock springboard-columns -int 7
defaults write com.apple.dock springboard-rows -int 7
简单的讲讲nginx+php的一些常用优化，以及相关的内核参数优化。
1. TCP 与 UNIX 套接字
UNIX 域套接字提供的性能略高于 TCP 套接字在回送接口上的性能（较少的数据复制，较少的上下文切换）。如果每个服务器需要支持超过 1000 个连接，请使用 TCP 套接字 - 它们可以更好地扩展。
...使用FFmpeg中的adelay和amix滤镜给音频做混音
在30秒后混合1个音频
ffmpeg -i 1-1.mp3 -i 2.mp3 -filter_complex "[1]adelay=delays=30s:all=1[aud1];[0][aud1]amix=inputs=2" -vsync 2 -y 3.mp3
在30秒后混合2个音频
ffmpeg -i 1-1.mp3 -i 2.mp3 -i 3.mp3 -filter_complex "[1]adelay=delays=30s:all=1[aud1];[2]adelay=delays=30s:all=1[aud2];[0][aud1][aud2]amix=inputs=3" -vsync 2 -y 4.mp3
混合多个参照混合2个的命令修改下即可
...修改supervisord配置突破1024最大连接数
最近在使用supervisord服务时发现，无论如何修改系统的最大连接数，由supervisord管理的程序都无法突破1024的限制。
...图片水印、文字水印、画中画
ffmpeg -i input.mp4 -vf "movie=wenzi.png[watermark];[in][watermark] overlay=main_w-overlay_w-10:main_h-overlay_h-10[out] " output.mp4
-i :一般表示输入
input.mp4:这里表示要处理的视频源
-vf:滤镜相关，视频裁剪，水印等等操作都需要它完成
...
Too many open files、获取不到$HOME等
vim /etc/supervisord.conf
[supervisord]
minfds=81920
minprocs=81920
# systemctl restart supervisord
[program:apache2]
command=/home/chrism/bin/httpd -c "ErrorLog /dev/stdout" -DFOREGROUND
user=chrism
environment=HOME="/home/chrism",USER="chrism"
supervisorctl update
使用deviceQuery获取显卡信息
Linux、nvidia、cuda
/usr/local/cuda/extras/demo_suite/deviceQuery
CUDA Device Query (Runtime API) version (CUDART static linking)
Detected 2 CUDA Capable device(s)
Device 0: "GeForce RTX 2080 Ti"
CUDA Driver Version / Runtime Version 10.1 / 10.1
CUDA Capability Major/Minor version number: 7.5
Total amount of global memory: 11019 MBytes (11554717696 bytes)
(68) Multiprocessors, ( 64) CUDA Cores/MP: 4352 CUDA Cores
GPU Max Clock rate: 1545 MHz (1.54 GHz)
Memory Clock rate: 7000 Mhz
Memory Bus Width: 352-bit
L2 Cache Size: 5767168 bytes
Maximum Texture Dimension Size (x,y,z) 1D=(131072), 2D=(131072, 65536), 3D=(16384, 16384, 16384)
Maximum Layered 1D Texture Size, (num) layers 1D=(32768), 2048 layers
Maximum Layered 2D Texture Size, (num) layers 2D=(32768, 32768), 2048 layers
Total amount of constant memory: 65536 bytes
Total amount of shared memory per block: 49152 bytes
Total number of registers available per block: 65536
Warp size: 32
Maximum number of threads per multiprocessor: 1024
Maximum number of threads per block: 1024
Max dimension size of a thread block (x,y,z): (1024, 1024, 64)
Max dimension size of a grid size (x,y,z): (2147483647, 65535, 65535)
Maximum memory pitch: 2147483647 bytes
Texture alignment: 512 bytes
Concurrent copy and kernel execution: Yes with 3 copy engine(s)
Run time limit on kernels: No
Integrated GPU sharing Host Memory: No
Support host page-locked memory mapping: Yes
Alignment requirement for Surfaces: Yes
Device has ECC support: Disabled
Device supports Unified Addressing (UVA): Yes
Device supports Compute Preemption: Yes
Supports Cooperative Kernel Launch: Yes
Supports MultiDevice Co-op Kernel Launch: Yes
Device PCI Domain ID / Bus ID / location ID: 0 / 1 / 0
Compute Mode:
< Default (multiple host threads can use ::cudaSetDevice() with device simultaneously) >
Device 1: "GeForce RTX 2080 Ti"
CUDA Driver Version / Runtime Version 10.1 / 10.1
CUDA Capability Major/Minor version number: 7.5
Total amount of global memory: 11019 MBytes (11554717696 bytes)
(68) Multiprocessors, ( 64) CUDA Cores/MP: 4352 CUDA Cores
GPU Max Clock rate: 1545 MHz (1.54 GHz)
Memory Clock rate: 7000 Mhz
Memory Bus Width: 352-bit
L2 Cache Size: 5767168 bytes
Maximum Texture Dimension Size (x,y,z) 1D=(131072), 2D=(131072, 65536), 3D=(16384, 16384, 16384)
Maximum Layered 1D Texture Size, (num) layers 1D=(32768), 2048 layers
Maximum Layered 2D Texture Size, (num) layers 2D=(32768, 32768), 2048 layers
Total amount of constant memory: 65536 bytes
Total amount of shared memory per block: 49152 bytes
Total number of registers available per block: 65536
Warp size: 32
Maximum number of threads per multiprocessor: 1024
Maximum number of threads per block: 1024
Max dimension size of a thread block (x,y,z): (1024, 1024, 64)
Max dimension size of a grid size (x,y,z): (2147483647, 65535, 65535)
Maximum memory pitch: 2147483647 bytes
Texture alignment: 512 bytes
Concurrent copy and kernel execution: Yes with 3 copy engine(s)
Run time limit on kernels: No
Integrated GPU sharing Host Memory: No
Support host page-locked memory mapping: Yes
Alignment requirement for Surfaces: Yes
Device has ECC support: Disabled
Device supports Unified Addressing (UVA): Yes
Device supports Compute Preemption: Yes
Supports Cooperative Kernel Launch: Yes
Supports MultiDevice Co-op Kernel Launch: Yes
Device PCI Domain ID / Bus ID / location ID: 0 / 2 / 0
Compute Mode:
< Default (multiple host threads can use ::cudaSetDevice() with device simultaneously) >
> Peer access from GeForce RTX 2080 Ti (GPU0) -> GeForce RTX 2080 Ti (GPU1) : Yes
> Peer access from GeForce RTX 2080 Ti (GPU1) -> GeForce RTX 2080 Ti (GPU0) : Yes
deviceQuery, CUDA Driver = CUDART, CUDA Driver Version = 10.1, CUDA Runtime Version = 10.1, NumDevs = 2
https://github.com/NVIDIA/cuda-samples/tree/master/Samples/deviceQuery
...ffprobe是ffmpeg提供的三大工具之一，用来查看音视频文件的各种信息，比如：封装格式、音频/视频流信息、数据包信息等。
ffprobe的源码是ffprobe.c，开发过程中如果想获取ffprobe查看的信息，可以通过分析源码，获得对应字段。
...