CentOS安装和使用FFmpeg

$ sudo yum install https://download1.rpmfusion.org/free/el/rpmfusion-free-release-8.noarch.rpm

$ sudo yum install http://rpmfind.net/linux/epel/7/x86_64/Packages/s/SDL2-2.0.10-1.el7.x86_64.rpm

$ sudo yum install ffmpeg ffmpeg-devel

$ rpm -qi ffmpeg
$ ffmpeg -version

ffmpeg [global_options] {[input_file_options] -i input_url} ... {[output_file_options] output_url} ...

<span class="c1"># -r: 抽帧速率，即从视频中每秒钟抽取图片的数量。1代表每秒抽取一帧。</span>
<span class="c1"># -q:v 2  表示输出的图片质量，一般是1到5之间（1 为质量最高）</span>
ffmpeg -i test.mov -r <span class="m">1</span> -f image2 foo-%03d.jpeg
ffmpeg -i test.mov -r <span class="m">1</span> -q:v <span class="m">2</span> -f image2 foo-%03d.jpeg

<span class="c1"># 每一秒输出一帧图像为图片, 图片命名为 out1.png, out2.png, out3.png,依次顺序输出.</span>
ffmpeg -i input.flv -vf <span class="nv">fps</span><span class="o">=</span><span class="m">1</span> out%d.png
<span class="c1"># 每一分钟截一次图,例子中的 %03d 为用来规定每个输出图片的序数将格式化使用3位数.</span>
ffmpeg -i myvideo.avi -vf <span class="nv">fps</span><span class="o">=</span>1/60 img%03d.jpg

<span class="c1"># 实践中前面放方法最常见</span>

<span class="c1"># 耗时0.05s</span>
ffmpeg -ss 00:00:30 -i test.mp4 -vframes <span class="m">1</span> target.jpg

<span class="c1"># 耗时0.56s</span>
ffmpeg -i test.mp4 -ss 00:00:30  -vframes <span class="m">1</span> target.jpg

# 抽取I帧
ffmpeg -i test.mp4 -vf "select=eq(pict_type\,I)"  -vsync vfr -qscale:v 2 -f image2 ./foo-%03d.jpeg

# 抽取P帧
ffmpeg -i test.mp4 -vf "select=eq(pict_type\,P)"  -vsync vfr -qscale:v 2 -f image2 ./foo-%03d.jpeg

# 抽取B帧
ffmpeg -i test.mp4 -vf "select=eq(pict_type\,B)"  -vsync vfr -qscale:v 2 -f image2 ./foo-%03d.jpeg

<span class="c1"># 其中0.6表示帧为新场景的概率</span>
ffmpeg -i test.mp4 -filter:v <span class="s2">"select='gt(scene,0.6)',showinfo"</span> -f null - 2><span class="p">&</span><span class="m">1</span>