Demuxers
********

Demuxers are configured elements in FFmpeg which allow to read the multimedia streams from a particular type of file.

When you configure your FFmpeg build, all the supported demuxers are enabled by default. You can list all available ones using the configure option "--list-demuxers".

You can disable all the demuxers using the configure option "--disable-demuxers", and selectively enable a single demuxer with the option "--enable-demuxer=DEMUXER", or disable it with the option "--disable-demuxer=DEMUXER".

The option "-formats" of the ff* tools will display the list of enabled demuxers.

The description of some of the currently available demuxers follows.

image2
======

Image file demuxer.

This demuxer reads from a list of image files specified by a pattern. The syntax and meaning of the pattern is specified by the option PATTERN_TYPE.

The pattern may contain a suffix which is used to automatically determine the format of the images contained in the files.

The size, the pixel format, and the format of each image must be the same for all the files in the sequence.

This demuxer accepts the following options:

framerate
     Set the framerate for the video stream. It defaults to 25.

loop
     If set to 1, loop over the input. Default value is 0.

pattern_type
     Select the pattern type used to interpret the provided filename.

     PATTERN_TYPE accepts one of the following values.

     sequence
          Select a sequence pattern type, used to specify a sequence of files indexed by sequential numbers.

          A sequence pattern may contain the string "%d" or "%0Nd", which specifies the position of the characters representing a sequential number in each filename matched by the pattern. If the form "%d0Nd" is used, the string representing the number in each filename is 0-padded and N is the total number of 0-padded digits representing the number. The literal character '%' can be specified in the pattern with the string "%%".

          If the sequence pattern contains "%d" or "%0Nd", the first filename of the file list specified by the pattern must contain a number inclusively contained between START_NUMBER and START_NUMBER+START_NUMBER_RANGE-1, and all the following numbers must be sequential.

          For example the pattern "img-%03d.bmp" will match a sequence of filenames of the form img-001.bmp, img-002.bmp, ..., img-010.bmp, etc.; the pattern "i%%m%%g-%d.jpg" will match a sequence of filenames of the form i%m%g-1.jpg, i%m%g-2.jpg, ..., i%m%g-10.jpg, etc.

          Note that the pattern must not necessarily contain "%d" or "%0Nd", for example to convert a single image file img.jpeg you can employ the command:

               ffmpeg -i img.jpeg img.png

     glob
          Select a glob wildcard pattern type.

          The pattern is interpreted like a glob() pattern. This is only selectable if libavformat was compiled with globbing support.

     glob_sequence (deprecated, will be removed)
          Select a mixed glob wildcard/sequence pattern.

          If your version of libavformat was compiled with globbing support, and the provided pattern contains at least one glob meta character among %*?[]{} that is preceded by an unescaped "%", the pattern is interpreted like a glob() pattern, otherwise it is interpreted like a sequence pattern.

          All glob special characters %*?[]{} must be prefixed with "%". To escape a literal "%" you shall use "%%".

          For example the pattern foo-%*.jpeg will match all the filenames prefixed by "foo-" and terminating with ".jpeg", and foo-%?%?%?.jpeg will match all the filenames prefixed with "foo-", followed by a sequence of three characters, and terminating with ".jpeg".

          This pattern type is deprecated in favor of GLOB and SEQUENCE.

     Default value is GLOB_SEQUENCE.

pixel_format
     Set the pixel format of the images to read. If not specified the pixel format is guessed from the first image file in the sequence.

start_number
     Set the index of the file matched by the image file pattern to start to read from. Default value is 0.

start_number_range
     Set the index interval range to check when looking for the first image file in the sequence, starting from START_NUMBER. Default value is 5.

video_size
     Set the video size of the images to read. If not specified the video size is guessed from the first image file in the sequence.

Examples
--------

  * Use ffmpeg for creating a video from the images in the file sequence img-001.jpeg, img-002.jpeg, ..., assuming an input frame rate of 10 frames per second:

          ffmpeg -i 'img-%03d.jpeg' -r 10 out.mkv

  * As above, but start by reading from a file with index 100 in the sequence:

          ffmpeg -start_number 100 -i 'img-%03d.jpeg' -r 10 out.mkv

  * Read images matching the "*.png" glob pattern , that is all the files terminating with the ".png" suffix:

          ffmpeg -pattern_type glob -i "*.png" -r 10 out.mkv

applehttp
=========

Apple HTTP Live Streaming demuxer.

This demuxer presents all AVStreams from all variant streams. The id field is set to the bitrate variant index number. By setting the discard flags on AVStreams (by pressing 'a' or 'v' in ffplay), the caller can decide which variant streams to actually receive. The total bitrate of the variant that the stream belongs to is available in a metadata key named "variant_bitrate".

sbg
===

SBaGen script demuxer.

This demuxer reads the script language used by SBaGen http://uazu.net/sbagen/ to generate binaural beats sessions. A SBG script looks like that:

     -SE
     a: 300-2.5/3 440+4.5/0
     b: 300-2.5/0 440+4.5/3
     off: -
     NOW      == a
     +0:07:00 == b
     +0:14:00 == a
     +0:21:00 == b
     +0:30:00    off

A SBG script can mix absolute and relative timestamps. If the script uses either only absolute timestamps (including the script start time) or only relative ones, then its layout is fixed, and the conversion is straightforward. On the other hand, if the script mixes both kind of timestamps, then the NOW reference for relative timestamps will be taken from the current time of day at the time the script is read, and the script layout will be frozen according to that reference. That means that if the script is directly played, the actual times will match the absolute timestamps up to the sound controller's clock accuracy, but if the user somehow pauses the playback or seeks, all times will be shifted accordingly.

concat
======

Virtual concatenation script demuxer.

This demuxer reads a list of files and other directives from a text file and demuxes them one after the other, as if all their packet had been muxed together.

The timestamps in the files are adjusted so that the first file starts at 0 and each next file starts where the previous one finishes. Note that it is done globally and may cause gaps if all streams do not have exactly the same length.

All files must have the same streams (same codecs, same time base, etc.).

This script format can currently not be probed, it must be specified explicitly.

Syntax
------

The script is a text file in extended-ASCII, with one directive per line. Empty lines, leading spaces and lines starting with '#' are ignored. The following directive is recognized:

file PATH
     Path to a file to read; special characters and spaces must be escaped with backslash or single quotes.

tedcaptions
===========

JSON captions used for TED Talks (http://www.ted.com/).

TED does not provide links to the captions, but they can be guessed from the page. The file tools/bookmarklets.html from the FFmpeg source tree contains a bookmarklet to expose them.

This demuxer accepts the following option:

start_time
     Set the start time of the TED talk, in milliseconds. The default is 15000 (15s). It is used to sync the captions with the downloadable videos, because they include a 15s intro.

Example: convert the captions to a format most players understand:

     ffmpeg -i http://www.ted.com/talks/subtitles/id/1/lang/en talk1-en.srt