Also do not mix options which belong to different files. verbosity level), which should be specified first.ĭo not mix input and output files - first specify all input files, then all output files. Exceptions from this rule are the global options (e.g. Each occurrence is then applied to the next input or output file. Therefore, order is important, and you can have the same option on the command line multiple times. Also see the Stream specifiers chapter.Īs a general rule, options are applied to the next specified file. 2:3 refers to the fourth stream in the third input file. Similarly, streams within a file are referred to by their indices. the first input file is 0, the second is 1, etc. To refer to input files in options, you must use their indices (0-based). Selecting which streams from which inputs will go into which output is either done automatically or with the -map option (see the Stream selection chapter). The allowed number and/or types of streams may be limited by the container format.

Anything found on the command line which cannot be interpreted as an option is considered to be an output url.Įach input or output url can, in principle, contain any number of streams of different types (video/audio/subtitle/attachment/data). It can also convert between arbitrary sample rates and resize video on the fly with a high quality polyphase filter.įfmpeg 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. DESCRIPTIONįfmpeg is a very fast video and audio converter that can also grab from a live audio/video source.

Ffmpeg h264 aac srt