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.
Each input or output file 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 refers to the fourth stream in the third input file. 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. 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.
tries to keep them synchronized by tracking lowest timestamp on any active input stream.