mirror of https://git.ffmpeg.org/ffmpeg.git
302 lines
10 KiB
Plaintext
302 lines
10 KiB
Plaintext
@chapter Demuxers
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@c man begin DEMUXERS
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Demuxers are configured elements in FFmpeg which allow to read the
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multimedia streams from a particular type of file.
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When you configure your FFmpeg build, all the supported demuxers
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are enabled by default. You can list all available ones using the
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configure option @code{--list-demuxers}.
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You can disable all the demuxers using the configure option
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@code{--disable-demuxers}, and selectively enable a single demuxer with
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the option @code{--enable-demuxer=@var{DEMUXER}}, or disable it
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with the option @code{--disable-demuxer=@var{DEMUXER}}.
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The option @code{-formats} of the ff* tools will display the list of
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enabled demuxers.
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The description of some of the currently available demuxers follows.
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@section applehttp
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Apple HTTP Live Streaming demuxer.
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This demuxer presents all AVStreams from all variant streams.
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The id field is set to the bitrate variant index number. By setting
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the discard flags on AVStreams (by pressing 'a' or 'v' in ffplay),
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the caller can decide which variant streams to actually receive.
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The total bitrate of the variant that the stream belongs to is
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available in a metadata key named "variant_bitrate".
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@section concat
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Virtual concatenation script demuxer.
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This demuxer reads a list of files and other directives from a text file and
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demuxes them one after the other, as if all their packet had been muxed
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together.
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The timestamps in the files are adjusted so that the first file starts at 0
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and each next file starts where the previous one finishes. Note that it is
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done globally and may cause gaps if all streams do not have exactly the same
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length.
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All files must have the same streams (same codecs, same time base, etc.).
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@subsection Syntax
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The script is a text file in extended-ASCII, with one directive per line.
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Empty lines, leading spaces and lines starting with '#' are ignored. The
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following directive is recognized:
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@table @option
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@item @code{file @var{path}}
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Path to a file to read; special characters and spaces must be escaped with
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backslash or single quotes.
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All subsequent directives apply to that file.
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@item @code{ffconcat version 1.0}
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Identify the script type and version. It also sets the @option{safe} option
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to 1 if it was to its default -1.
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To make FFmpeg recognize the format automatically, this directive must
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appears exactly as is (no extra space or byte-order-mark) on the very first
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line of the script.
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@item @code{duration @var{dur}}
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Duration of the file. This information can be specified from the file;
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specifying it here may be more efficient or help if the information from the
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file is not available or accurate.
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@end table
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@subsection Options
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This demuxer accepts the following option:
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@table @option
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@item safe
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If set to 1, reject unsafe file paths. A file path is considered safe if it
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does not contain a protocol specification and is relative and all components
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only contain characters from the portable character set (letters, digits,
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period, underscore and hyphen) and have no period at the beginning of a
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component.
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If set to 0, any file name is accepted.
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The default is -1, it is equivalent to 1 if the format was automatically
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probed and 0 otherwise.
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@end table
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@section image2
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Image file demuxer.
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This demuxer reads from a list of image files specified by a pattern.
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The syntax and meaning of the pattern is specified by the
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option @var{pattern_type}.
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The pattern may contain a suffix which is used to automatically
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determine the format of the images contained in the files.
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The size, the pixel format, and the format of each image must be the
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same for all the files in the sequence.
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This demuxer accepts the following options:
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@table @option
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@item framerate
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Set the framerate for the video stream. It defaults to 25.
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@item loop
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If set to 1, loop over the input. Default value is 0.
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@item pattern_type
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Select the pattern type used to interpret the provided filename.
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@var{pattern_type} accepts one of the following values.
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@table @option
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@item sequence
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Select a sequence pattern type, used to specify a sequence of files
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indexed by sequential numbers.
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A sequence pattern may contain the string "%d" or "%0@var{N}d", which
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specifies the position of the characters representing a sequential
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number in each filename matched by the pattern. If the form
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"%d0@var{N}d" is used, the string representing the number in each
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filename is 0-padded and @var{N} is the total number of 0-padded
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digits representing the number. The literal character '%' can be
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specified in the pattern with the string "%%".
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If the sequence pattern contains "%d" or "%0@var{N}d", the first filename of
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the file list specified by the pattern must contain a number
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inclusively contained between @var{start_number} and
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@var{start_number}+@var{start_number_range}-1, and all the following
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numbers must be sequential.
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For example the pattern "img-%03d.bmp" will match a sequence of
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filenames of the form @file{img-001.bmp}, @file{img-002.bmp}, ...,
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@file{img-010.bmp}, etc.; the pattern "i%%m%%g-%d.jpg" will match a
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sequence of filenames of the form @file{i%m%g-1.jpg},
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@file{i%m%g-2.jpg}, ..., @file{i%m%g-10.jpg}, etc.
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Note that the pattern must not necessarily contain "%d" or
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"%0@var{N}d", for example to convert a single image file
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@file{img.jpeg} you can employ the command:
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@example
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ffmpeg -i img.jpeg img.png
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@end example
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@item glob
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Select a glob wildcard pattern type.
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The pattern is interpreted like a @code{glob()} pattern. This is only
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selectable if libavformat was compiled with globbing support.
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@item glob_sequence @emph{(deprecated, will be removed)}
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Select a mixed glob wildcard/sequence pattern.
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If your version of libavformat was compiled with globbing support, and
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the provided pattern contains at least one glob meta character among
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@code{%*?[]@{@}} that is preceded by an unescaped "%", the pattern is
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interpreted like a @code{glob()} pattern, otherwise it is interpreted
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like a sequence pattern.
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All glob special characters @code{%*?[]@{@}} must be prefixed
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with "%". To escape a literal "%" you shall use "%%".
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For example the pattern @code{foo-%*.jpeg} will match all the
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filenames prefixed by "foo-" and terminating with ".jpeg", and
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@code{foo-%?%?%?.jpeg} will match all the filenames prefixed with
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"foo-", followed by a sequence of three characters, and terminating
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with ".jpeg".
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This pattern type is deprecated in favor of @var{glob} and
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@var{sequence}.
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@end table
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Default value is @var{glob_sequence}.
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@item pixel_format
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Set the pixel format of the images to read. If not specified the pixel
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format is guessed from the first image file in the sequence.
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@item start_number
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Set the index of the file matched by the image file pattern to start
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to read from. Default value is 0.
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@item start_number_range
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Set the index interval range to check when looking for the first image
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file in the sequence, starting from @var{start_number}. Default value
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is 5.
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@item video_size
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Set the video size of the images to read. If not specified the video
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size is guessed from the first image file in the sequence.
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@end table
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@subsection Examples
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@itemize
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@item
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Use @command{ffmpeg} for creating a video from the images in the file
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sequence @file{img-001.jpeg}, @file{img-002.jpeg}, ..., assuming an
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input frame rate of 10 frames per second:
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@example
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ffmpeg -i 'img-%03d.jpeg' -r 10 out.mkv
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@end example
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@item
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As above, but start by reading from a file with index 100 in the sequence:
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@example
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ffmpeg -start_number 100 -i 'img-%03d.jpeg' -r 10 out.mkv
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@end example
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@item
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Read images matching the "*.png" glob pattern , that is all the files
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terminating with the ".png" suffix:
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@example
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ffmpeg -pattern_type glob -i "*.png" -r 10 out.mkv
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@end example
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@end itemize
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@section rawvideo
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Raw video demuxer.
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This demuxer allows to read raw video data. Since there is no header
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specifying the assumed video parameters, the user must specify them
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in order to be able to decode the data correctly.
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This demuxer accepts the following options:
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@table @option
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@item framerate
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Set input video frame rate. Default value is 25.
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@item pixel_format
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Set the input video pixel format. Default value is @code{yuv420p}.
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@item video_size
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Set the input video size. This value must be specified explicitly.
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@end table
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For example to read a rawvideo file @file{input.raw} with
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@command{ffplay}, assuming a pixel format of @code{rgb24}, a video
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size of @code{320x240}, and a frame rate of 10 images per second, use
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the command:
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@example
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ffplay -f rawvideo -pixel_format rgb24 -video_size 320x240 -framerate 10 input.raw
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@end example
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@section sbg
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SBaGen script demuxer.
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This demuxer reads the script language used by SBaGen
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@url{http://uazu.net/sbagen/} to generate binaural beats sessions. A SBG
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script looks like that:
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@example
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-SE
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a: 300-2.5/3 440+4.5/0
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b: 300-2.5/0 440+4.5/3
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off: -
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NOW == a
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+0:07:00 == b
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+0:14:00 == a
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+0:21:00 == b
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+0:30:00 off
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@end example
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A SBG script can mix absolute and relative timestamps. If the script uses
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either only absolute timestamps (including the script start time) or only
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relative ones, then its layout is fixed, and the conversion is
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straightforward. On the other hand, if the script mixes both kind of
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timestamps, then the @var{NOW} reference for relative timestamps will be
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taken from the current time of day at the time the script is read, and the
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script layout will be frozen according to that reference. That means that if
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the script is directly played, the actual times will match the absolute
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timestamps up to the sound controller's clock accuracy, but if the user
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somehow pauses the playback or seeks, all times will be shifted accordingly.
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@section tedcaptions
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JSON captions used for @url{http://www.ted.com/, TED Talks}.
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TED does not provide links to the captions, but they can be guessed from the
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page. The file @file{tools/bookmarklets.html} from the FFmpeg source tree
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contains a bookmarklet to expose them.
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This demuxer accepts the following option:
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@table @option
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@item start_time
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Set the start time of the TED talk, in milliseconds. The default is 15000
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(15s). It is used to sync the captions with the downloadable videos, because
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they include a 15s intro.
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@end table
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Example: convert the captions to a format most players understand:
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@example
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ffmpeg -i http://www.ted.com/talks/subtitles/id/1/lang/en talk1-en.srt
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@end example
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@c man end DEMUXERS
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