ffmpeg是一套可以用来记录、转换数字音频、视频，并能将其转化为流的开源计算机程序。它提供了录制、转换以及流化音视频的完整解决方案。

　　ffmpeg is a very fast video and audio converter that can also grab from a live audio/video source. It can also convert between arbitrary sample rates and resize video on the fly with a high quality polyphase filter.

　　翻译：ffmpeg是一个高效的音视频转换器，它也可以抓取在线直播的音视频。它能够实现任意采样率间转换，并且可通过高质量的多相滤波器动态调整视频的大小。

　　ffmpeg reads from an arbitrary number of input "files" (which can be regular files, pipes, network streams, grabbing devices, etc.), specified by the -i option, and writes to an arbitrary number of output "files", which are specified by a plain output url. Anything found on the command line which cannot be interpreted as an option is considered to be an output url.

　　翻译：ffmpeg通过选项-i，读取任意数量的输入文件（常规文件、管道、网络流、抓取设备等），并写入任意数量的输出文件，这些文件就是普通的输出URL。在命令行中出现的任意无法解释为选项的参数将被当作输出URL。

　　Each input or output url can, in principle, contain any number of streams of different types (video/audio/subtitle/attachment/data). The allowed number and/or types of streams may be limited by the container format. Selecting which streams from which inputs will go into which output is either done automatically or with the -map option.

　　翻译：原则上来说，每个输入输出URL都可以包含任意数量不同类型的流（视频/音频/字幕/附件/数据）。允许的流的数量和/或类型可能受限于容器的格式。选择哪个流从哪里输入，将进入那个输出可以自动完成，当然也可以通过-map选项设置。

　　To refer to input files in options, you must use their indices (0-based). E.g. the first input file is 0, the second is 1, etc. Similarly, streams within a file are referred to by their indices. E.g. 2:3 refers to the fourth stream in the third input file.

　　翻译：为了在选项中引入输入文件，必须使用他们的索引，例如：第一个输入文件是0，第二个是1等等。同理，文件的流也通过他们的索引来引用，例如：2:3表示第三个输入文件中的第四个流。

　　As a general rule, options are applied to the next specified file. Therefore, order is important, and you can have the same option on the command line multiple times. Each occurrence is then applied to the next input or output file. Exceptions from this rule are the global options (e.g. verbosity level), which should be specified first.

　　翻译：一般来说，选项应用于下一个指定文件。因此，顺序是重要的，你可以在命令行中多次使用相同的选项，每一次的出现将作用于下一个输入或输出文件。这个规则的例外就是全局选项（例如：冗余等级）应该优先设置。

　　Do not mix input and output files – first specify all input files, then all output files. Also do not mix options which belong to different files. All options apply ONLY to the next input or output file and are reset between files.

　　翻译：不要混合输入和输出文件：首先应该指定所有的输入文件，然后才是所有的输出文件。当然，也不要混合属于不同文件的选项，所有的选项仅仅应用于下一个输入或输出文件，并且在文件间已经被重置了。

　　【命令行】

　　ffmpeg [global_options] {[input_file_options] -i input_url} ... {[output_file_options] output_url} ...【参考命令】

　　To set the video bitrate of the output file to 64 kbit/s:

　　ffmpeg -i input.avi -b:v 64k -bufsize 64k output.aviTo force the frame rate of the output file to 24 fps:

　　ffmpeg -i input.avi -r 24 output.aviTo force the frame rate of the input file (valid for raw formats only) to 1 fps and the frame rate of the output file to 24 fps:

　　ffmpeg -r 1 -i input.m2v -r 24 output.avi码字不易，喜欢的话就点个赞，下呗！您的是我最大的动力，谢谢啦！

　　代码混淆器，神一般存在的源码守护者，你值得拥有

　　Alpine Linux，一定不会使你失望

　　Gradle版本「若依」面世，免费拿走不谢