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· 2 min read

将 webm 格式转换成 mp4 格式命令:

# 默认使用的是最高质量的转换设置
ffmpeg -i input.webm output.mp4

# 如果你想要更小的文件大小，可以通过添加比特率参数来降低质量， -b:v 是视频比特率，-b:a 是音频比特率
ffmpeg -i input.webm -b:v 1M -b:a 192k output.mp4

如果上述命令返回以下错误:

[libx264 @ 0x558605199840] height not divisible by 2 (1364x1015)
Error initializing output stream 0:0 -- Error while opening encoder for output stream #0:0 - maybe incorrect parameters such as bit_rate, rate, width or height

是由于视频的宽度或高度不能被2整除。H.264 编码（在 MP4 文件中常用）需要视频的宽度和高度都能被2整除。为了修复这个错误，你可以在FFmpeg命令中加入-vf "pad=ceil(iw/2)2:ceil(ih/2)2"来强制视频的宽度和高度都是偶数。 这个设置将自动将宽度和高度调整到最接近的偶数。命令如下：

ffmpeg -i input.webm -vf "pad=ceil(iw/2)*2:ceil(ih/2)*2" output.mp4

· 15 min read

在 Chrome 浏览器中使用以下代码:

document.body.addEventListener("touchmove", (e) => {
    console.log(e);
})

会在控制台看到一个警告信息:

[Violation] Added non-passive event listener to a scroll-blocking 'touchmove' event. Consider marking event handler as 'passive' to make the page more responsive. See https://www.chromestatus.com/feature/5745543795965952

· One min read

Gradle 默认使用 ~/.gradle 目录存放资源, 通过修改环境变量 GRADLE_USER_HOME 可以修改默认目录:

~/.bashrc
export GRADLE_USER_HOME="/dta/programs/gradle"

使用阿里云镜像​

创建文件 $GRADLE_USER_HOME/init.gradle, 内容如下:

allprojects{
    repositories {
        def ALIYUN_REPOSITORY_URL = 'https://maven.aliyun.com/repository/public'
        def ALIYUN_JCENTER_URL = 'https://maven.aliyun.com/repository/public'
        def ALIYUN_GOOGLE_URL = 'https://maven.aliyun.com/repository/google'
        def ALIYUN_GRADLE_PLUGIN_URL = 'https://maven.aliyun.com/repository/gradle-plugin'
        all { ArtifactRepository repo ->
            if(repo instanceof MavenArtifactRepository){
                def url = repo.url.toString()
                if (url.startsWith('https://repo1.maven.org/maven2/')) {
                    project.logger.lifecycle "Repository ${repo.url} replaced by $ALIYUN_REPOSITORY_URL."
                    remove repo
                }
                if (url.startsWith('https://jcenter.bintray.com/')) {
                    project.logger.lifecycle "Repository ${repo.url} replaced by $ALIYUN_JCENTER_URL."
                    remove repo
                }
                if (url.startsWith('https://dl.google.com/dl/android/maven2/')) {
                    project.logger.lifecycle "Repository ${repo.url} replaced by $ALIYUN_GOOGLE_URL."
                    remove repo
                }
                if (url.startsWith('https://plugins.gradle.org/m2/')) {
                    project.logger.lifecycle "Repository ${repo.url} replaced by $ALIYUN_GRADLE_PLUGIN_URL."
                    remove repo
                }
            }
        }
        maven { url ALIYUN_REPOSITORY_URL }
        maven { url ALIYUN_JCENTER_URL }
        maven { url ALIYUN_GOOGLE_URL }
        maven { url ALIYUN_GRADLE_PLUGIN_URL }
    }
}