<?xml version="1.0" encoding="utf-8" ?><rss version="2.0"><channel><title><![CDATA[itisyang]]></title><description><![CDATA[——大道至简]]></description><link>https://blog.youkuaiyun.com/itisyang</link><language>zh-cn</language><generator>https://blog.youkuaiyun.com/</generator><copyright><![CDATA[Copyright &copy; itisyang]]></copyright><item><title><![CDATA[ffmpeg源码精读2，视频编码]]></title><link>https://blog.youkuaiyun.com/itisyang/article/details/123577609</link><guid>https://blog.youkuaiyun.com/itisyang/article/details/123577609</guid><author>itisyang</author><pubDate>Fri, 18 Mar 2022 16:33:42 +0800</pubDate><description><![CDATA[ffmpeg视频编码例子，解析主要流程。]]></description><category></category></item><item><title><![CDATA[ffmpeg vs2017的一种编译方式]]></title><link>https://blog.youkuaiyun.com/itisyang/article/details/123276483</link><guid>https://blog.youkuaiyun.com/itisyang/article/details/123276483</guid><author>itisyang</author><pubDate>Fri, 04 Mar 2022 14:55:53 +0800</pubDate><description><![CDATA[ffmpeg Windows vs2017编译，下载yasm，安装msys2，编译x264，编译zlib，编译fdk-aac]]></description><category></category></item><item><title><![CDATA[ffmpeg源码精读2，视频解码]]></title><link>https://blog.youkuaiyun.com/itisyang/article/details/122844515</link><guid>https://blog.youkuaiyun.com/itisyang/article/details/122844515</guid><author>itisyang</author><pubDate>Wed, 09 Feb 2022 16:45:46 +0800</pubDate><description><![CDATA[ffmpeg视频解码例子：https://git.ffmpeg.org/gitweb/ffmpeg.git/blob/HEAD:/doc/examples/decode_video.c
从main函数入手，核心接口：avcodec_find_decoder、av_parser_init、avcodec_alloc_context3、avcodec_open2、av_parser_parse2、avcodec_send_packet、avcodec_receive_frame
程序流程：

查找解码器
初始化]]></description><category></category></item><item><title><![CDATA[ffmpeg源码精读1，音视频处理概述]]></title><link>https://blog.youkuaiyun.com/itisyang/article/details/122682558</link><guid>https://blog.youkuaiyun.com/itisyang/article/details/122682558</guid><author>itisyang</author><pubDate>Tue, 25 Jan 2022 13:46:29 +0800</pubDate><description><![CDATA[一个视频包含封装+视频+音频。
简单来说，要处理一个视频分两步。
第一步是解封装（demux）
这一步能获取视频信息，如：编码器、帧率、pts起始值、时长、帧数、像素格式、音频采样格式、码率、宽高、色彩空间、色域、通道、采样率……
获取到了这些视频信息后，就能依据这些信息对视频数据包进行对应的解码操作。
第二步逐帧解码（decode）
通过循环读取视频数据包，根据编码器类型进行解码，会得到图像采样数据（YUV）或音频采样数据（PCM），后续再进行渲染或其他处理（如添加数据、保存等）

...]]></description><category></category></item><item><title><![CDATA[ffmpeg example decode_video 升级方案]]></title><link>https://blog.youkuaiyun.com/itisyang/article/details/107106076</link><guid>https://blog.youkuaiyun.com/itisyang/article/details/107106076</guid><author>itisyang</author><pubDate>Fri, 03 Jul 2020 15:09:29 +0800</pubDate><description><![CDATA[以 MPEG-1 为例的视频解码例子，不含封装，只解析裸流
流程：


视频数据包初始化，av_packet_alloc


查找 MPEG-1 解码器， avcodec_find_decoder


数据解析器初始化，av_parser_init


解码结构初始化，avcodec_alloc_context3


打开解码器，avcodec_open2


打开视频文件，fopen


解码视频帧初始化，av_frame_alloc


循环
读文件，fread
解析数据包，av_parser_pars]]></description><category></category></item><item><title><![CDATA[CFFI - ABI模式与API模式]]></title><link>https://blog.youkuaiyun.com/itisyang/article/details/82079131</link><guid>https://blog.youkuaiyun.com/itisyang/article/details/82079131</guid><author>itisyang</author><pubDate>Sun, 26 Aug 2018 11:32:02 +0800</pubDate><description><![CDATA[CFFI可以在四种模式中使用:“ABI”和“API”级别，每种模式都有 in-line 或 out- line 准备(或编译)

ABI模式从二进制级别访问库，而更快的API模式通过C编译器访问库

在 in-line 模式中，每次导入Python代码时都会设置所有内容 

在 out- line 模式中，有一个单独的准备步骤(可能还有C编译)，它生成一个模块，主程序可以导入该模块



简单例子...]]></description><category></category></item><item><title><![CDATA[CFFI - 简单使用]]></title><link>https://blog.youkuaiyun.com/itisyang/article/details/82078307</link><guid>https://blog.youkuaiyun.com/itisyang/article/details/82078307</guid><author>itisyang</author><pubDate>Sun, 26 Aug 2018 10:14:19 +0800</pubDate><description><![CDATA[使用CFFI作为已经编译好的C库的接口。

库譬如 piapprox.dll (Windows) 或 libpiapprox.so (Linux and others) 或者 libpiapprox.dylib (OS X)

库里面有个函数 float pi_approx(int n)

| 版权声明：itisyang，未经博主允许不得转载。https://blog.youkuaiyun.com/itisy...]]></description><category></category></item><item><title><![CDATA[CFFI - 简介]]></title><link>https://blog.youkuaiyun.com/itisyang/article/details/81489923</link><guid>https://blog.youkuaiyun.com/itisyang/article/details/81489923</guid><author>itisyang</author><pubDate>Tue, 07 Aug 2018 22:36:56 +0800</pubDate><description><![CDATA[CFFI可以通过Python调用C的功能接口，基于一种类C声明，基本可以直接和任何C代码交互。（类C声明通常直接拷贝头文件即可）

CFFI接口基于LuaJIT’s FFI，遵循下面几条原则：


目标是在不学习第三种语言的情况下从Python调用C代码。现有的替代方法要求用户学习特定语言(Cython、SWIG)或API (ctypes)。CFFI设计只要求用户知道C和Python，尽量减少需要...]]></description><category></category></item><item><title><![CDATA[pip缓慢或失败]]></title><link>https://blog.youkuaiyun.com/itisyang/article/details/81431181</link><guid>https://blog.youkuaiyun.com/itisyang/article/details/81431181</guid><author>itisyang</author><pubDate>Sun, 05 Aug 2018 14:52:30 +0800</pubDate><description><![CDATA[原因：


pip官方服务器访问慢
公司内网过滤




处理方法


pypi换源，推荐阿里云镜像



  pip国内的一些镜像


阿里云 https://mirrors.aliyun.com/pypi/simple/ 
中国科技大学 https://pypi.mirrors.ustc.edu.cn/simple/ 
豆瓣(douban) https://pypi.douban.com/si...]]></description><category></category></item><item><title><![CDATA[树莓派教程-连接ssh]]></title><link>https://blog.youkuaiyun.com/itisyang/article/details/80009606</link><guid>https://blog.youkuaiyun.com/itisyang/article/details/80009606</guid><author>itisyang</author><pubDate>Thu, 19 Apr 2018 19:25:42 +0800</pubDate><description><![CDATA[ssh默认连接：ip:22       pi  raspberry

最新的Raspbian 有可能默认关闭了ssh，同时串口可能没有数据输出（或乱码） 
在没有屏幕的时候将很难连接树莓派。 
解决办法： 
在SD卡中烧录好Raspbian 系统之后，在内存卡的根目录创建一个名为ssh的空文件夹



三种ssh连接树莓派的方法 
1. 有路由器的情况 
- 通过网线连接路由器，查看路由器下的设备...]]></description><category></category></item><item><title><![CDATA[树莓派教程-命令行连接wifi]]></title><link>https://blog.youkuaiyun.com/itisyang/article/details/79980517</link><guid>https://blog.youkuaiyun.com/itisyang/article/details/79980517</guid><author>itisyang</author><pubDate>Tue, 17 Apr 2018 20:44:45 +0800</pubDate><description><![CDATA[原文链接：https://blog.youkuaiyun.com/itisyang/article/details/79980517

sudo iwlist wlan0 scan列出所有可连接wifi

sudo vi /etc/wpa_supplicant/wpa_supplicant.conf

在文件的底部添加下面内容：

network={
    ssid=&quot;Your_wifi_ssif&quot;
   ...]]></description><category></category></item><item><title><![CDATA[树莓派教程-串口调试]]></title><link>https://blog.youkuaiyun.com/itisyang/article/details/79968592</link><guid>https://blog.youkuaiyun.com/itisyang/article/details/79968592</guid><author>itisyang</author><pubDate>Mon, 16 Apr 2018 23:41:20 +0800</pubDate><description><![CDATA[原文链接：https://blog.youkuaiyun.com/itisyang/article/details/79968592



最新的Raspbian串口连接没有数据输出

使用ssh连接树莓派之后 
- sudo raspi-config 
- Interfacing Options 
- Serial 
打开串口登录树莓派



正常情况串口四根线连接：


VCC-5V
GND-GND
TX...]]></description><category></category></item><item><title><![CDATA[树莓派教程-搭建文件下载服务器二]]></title><link>https://blog.youkuaiyun.com/itisyang/article/details/69802893</link><guid>https://blog.youkuaiyun.com/itisyang/article/details/69802893</guid><author>itisyang</author><pubDate>Sun, 09 Apr 2017 10:57:44 +0800</pubDate><description><![CDATA[原文链接：http://blog.youkuaiyun.com/itisyang/article/details/69802893 
本文使用原生的nginx，相对于使用openresty少了编译过程，并且更加轻量化 
- 树莓派3 
- nginx





安装nginx


sudo apt-get install nginx




配置

sudo vim /etc/nginx/nginx.conf...]]></description><category></category></item><item><title><![CDATA[树莓派教程-Samba服务器简易配置]]></title><link>https://blog.youkuaiyun.com/itisyang/article/details/69574094</link><guid>https://blog.youkuaiyun.com/itisyang/article/details/69574094</guid><author>itisyang</author><pubDate>Fri, 07 Apr 2017 17:36:28 +0800</pubDate><description><![CDATA[原文链接：http://blog.youkuaiyun.com/itisyang/article/details/69574094



samba安装

sudo apt-get install samba



smb.conf配置，此处配置了两个目录分别是用户home目录和tftp目录

[global] 
workgroup = WORKGROUP 
server string = Samba Ser...]]></description><category></category></item><item><title><![CDATA[树莓派教程-搭建文件下载服务器一]]></title><link>https://blog.youkuaiyun.com/itisyang/article/details/69569553</link><guid>https://blog.youkuaiyun.com/itisyang/article/details/69569553</guid><author>itisyang</author><pubDate>Fri, 07 Apr 2017 17:16:35 +0800</pubDate><description><![CDATA[原文链接：http://blog.youkuaiyun.com/itisyang/article/details/69569553


树莓派3
openresty






下载openresty及编译


下载  
前往官网 https://openresty.org 下载最新的openresty
安装依赖 
sudo apt install libreadline-dev libncurses5-de...]]></description><category></category></item><item><title><![CDATA[Python使用CFFI调用C动态库]]></title><link>https://blog.youkuaiyun.com/itisyang/article/details/54426631</link><guid>https://blog.youkuaiyun.com/itisyang/article/details/54426631</guid><author>itisyang</author><pubDate>Sat, 14 Jan 2017 14:37:30 +0800</pubDate><description><![CDATA[原文链接    https://blog.youkuaiyun.com/itisyang/article/details/54426631

初始化



from cffi import FFI
ffi = FFI()



加载C动态库



lib_IOTCAPIs = ffi.dlopen(&amp;amp;amp;amp;quot;./tutk_lib/libIOTCAPIs.so&amp;amp;amp;amp;quot;)

这种方法加载动态库若是多个库之间有交错调用，则会报错...]]></description><category></category></item><item><title><![CDATA[超轻JSON解析器]]></title><link>https://blog.youkuaiyun.com/itisyang/article/details/53190850</link><guid>https://blog.youkuaiyun.com/itisyang/article/details/53190850</guid><author>itisyang</author><pubDate>Wed, 16 Nov 2016 19:52:13 +0800</pubDate><description><![CDATA[超轻JSON解析器]]></description><category></category></item><item><title><![CDATA[C语言获取命令行输出]]></title><link>https://blog.youkuaiyun.com/itisyang/article/details/53190565</link><guid>https://blog.youkuaiyun.com/itisyang/article/details/53190565</guid><author>itisyang</author><pubDate>Wed, 16 Nov 2016 19:35:35 +0800</pubDate><description><![CDATA[C语言获取命令行输出]]></description><category></category></item><item><title><![CDATA[APUE3学习笔记-第二章-UNIX标准及实现]]></title><link>https://blog.youkuaiyun.com/itisyang/article/details/52207303</link><guid>https://blog.youkuaiyun.com/itisyang/article/details/52207303</guid><author>itisyang</author><pubDate>Sun, 14 Aug 2016 23:28:36 +0800</pubDate><description><![CDATA[——上善若水，大道至简
环境：Ubuntu 1604 LTS
编辑器：Vim
编译器：gcc
材料：UNIX环境高级编程第三版   Advanced Programming in the UNIX® Environment, Third Edition
原文链接：http://blog.youkuaiyun.com/itisyang/article/details/52207303
UNIX标准化ISO C此标]]></description><category></category></item><item><title><![CDATA[APUE3学习笔记-第一章-UNIX基础知识]]></title><link>https://blog.youkuaiyun.com/itisyang/article/details/52139493</link><guid>https://blog.youkuaiyun.com/itisyang/article/details/52139493</guid><author>itisyang</author><pubDate>Sat, 06 Aug 2016 23:43:31 +0800</pubDate><description><![CDATA[——上善若水，大道至简
环境：Ubuntu 1604 LTS
编辑器：Vim
编译器：gcc
材料：UNIX环境高级编程第三版   Advanced Programming in the UNIX® Environment, Third Edition
原文链接：http://blog.youkuaiyun.com/itisyang/article/details/52139493
UNIX体系结构登录在/et]]></description><category></category></item></channel></rss>