Quick & Dirty -- ffmpeg

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.

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.

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 (see the Stream selection chapter).

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. Also see the Stream specifiers chapter.

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.

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.

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

 ffmpeg -i input.avi -b:v 64k -bufsize 64k output.avi

To force the frame rate of the output file to 24 fps:

 ffmpeg -i input.avi -r 24 output.avi

To 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

Extract Opus from WEBM

This will extract the Opus stream from the Webm container without recoding.

 ffmpeg -i "input-filename.webm" -acodec copy "output-filename.webm"

Convert wav to flac

This will encode to a 176kHz 24-bit sample, stored as 32-bits.

 ffmpeg -i "input-filename.webm" -af aformat=s32:176000 "output-filename.flac"

This will encode to 16-bit and 44.1 kHz.

 ffmpeg -i "input-filename.webm" -af aformat=s16:44100 "output-filename.flac"