neulab/tldr huggingface dataset:
Gcal Copyright (c) 1994, 95, 96, 1997, 2000 Thomas Esken
This software doesn't claim completeness, correctness or usability.  On principle I will not be liable for any damages or losses (implicit or explicit), which result from using or handling my software.  If you use this software, you agree without any exception to this agreement, which binds you LEGALLY !!
Gcal is free software and distributed under the terms of the `GNU General Public License'; published by the `Free Software Foundation'; version 2 or (at your option) any later version.
Any suggestions, improvements, extensions, bug reports, donations, proposals for contract work, and so forth are welcome!  If you like this tool, I'd appreciate a postcard from you!
Enjoy it   =8^)
------------------------oOO      \\\_''/      OOo--------------------------- Thomas Esken               O     (/o-o\)     O  eMail: esken@gmx.net Im Hagenfeld 84                 ((  ^  ))       Phone: +49 251 232585 D-48147 Muenster; Germany    \____) ~ (____/    MotD : 2old2live, 2young2die
tcal(1), txt2gcal(1), gcal2txt(1), cal(1), calendar(1).
check-language-support(1)    General Commands Manual   check-language-support(1)
check-language-support - returns the list of missing packages in order to provide a complete language environment
check-language-support [options]
-l LANGUAGE, --language=LANGUAGE target language code - if omitted, check for all languages on the system
-d DATADIR, --datadir=DATADIR use an alternative data directory instead of the default /usr/share/language-selector
-a, --all check all available languages
--show-installed show installed packages as well as missing ones
This manpage has been written by Arne Goetje <arne@ubuntu.com>
FFMPEG(1)                                                              FFMPEG(1)
ffmpeg - ffmpeg video converter
ffmpeg [global_options] {[input_file_options] -i input_url} ... {[output_file_options] output_url} ...
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
The format option may be needed for raw input files.
The transcoding process in ffmpeg for each output can be described by the following diagram:
_______              ______________ |       |            |              | | input |  demuxer   | encoded data |   decoder | file  | ---------> | packets      | -----+ |_______|            |______________|      | v _________ |         | | decoded | | frames  | |_________| ________             ______________       | |        |           |              |      | | output | <-------- | encoded data | <----+ | file   |   muxer   | packets      |   encoder |________|           |______________|
ffmpeg calls the libavformat library (containing demuxers) to read input files and get packets containing encoded data from them. When there are multiple input files, ffmpeg tries to keep them synchronized by tracking lowest timestamp on any active input stream.
Encoded packets are then passed to the decoder (unless streamcopy is selected for the stream, see further for a description). The decoder produces uncompressed frames (raw video/PCM audio/...) which can be processed further by filtering (see next section). After filtering, the frames are passed to the encoder, which encodes them and outputs encoded packets. Finally those are passed to the muxer, which writes the encoded packets to the output file.
Filtering Before encoding, ffmpeg can process raw audio and video frames using filters from the libavfilter library. Several chained filters form a filter graph. ffmpeg distinguishes between two types of filtergraphs: simple and complex.
Simple filtergraphs
Simple filtergraphs are those that have exactly one input and output, both of the same type. In the above diagram they can be represented by simply inserting an additional step between decoding and encoding:
_________                        ______________ |         |                      |              | | decoded |                      | encoded data | | frames  |\                   _ | packets      | |_________| \                  /||______________| \   __________   / simple     _\||          | /  encoder filtergraph   | filtered |/ | frames   | |__________|
Simple filtergraphs are configured with the per-stream -filter option (with -vf and -af aliases for video and audio respectively).  A simple filtergraph for video can look for example like this:
_______        _____________        _______        ________ |       |      |             |      |       |      |        | | input | ---> | deinterlace | ---> | scale | ---> | output | |_______|      |_____________|      |_______|      |________|
Note that some filters change frame properties but not frame contents. E.g. the "fps" filter in the example above changes number of frames, but does not touch the frame contents. Another example is the "setpts" filter, which only sets timestamps and otherwise passes the frames unchanged.
Complex filtergraphs
Complex filtergraphs are those which cannot be described as simply a linear processing chain applied to one stream. This is the case, for example, when the graph has more than one input and/or output, or when output stream type is different from input. They can be represented with the following diagram:
_________ |         | | input 0 |\                    __________ |_________| \                  |          | \   _________    /| output 0 | \ |         |  / |__________| _________     \| complex | / |         |     |         |/ | input 1 |---->| filter  |\ |_________|     |         | \   __________ /| graph   |  \ |          | / |         |   \| output 1 | _________   /  |_________|    |__________| |         | / | input 2 |/ |_________|
Complex filtergraphs are configured with the -filter_complex option. Note that this option is global, since a complex filtergraph, by its nature, cannot be unambiguously associated with a single stream or file.
The -lavfi option is equivalent to -filter_complex.
A trivial example of a complex filtergraph is the "overlay" filter, which has two video inputs and one video output, containing one video overlaid on top of the other. Its audio counterpart is the "amix" filter.
Stream copy Stream copy is a mode selected by supplying the "copy" parameter to the -codec option. It makes ffmpeg omit the decoding and encoding step for the specified stream, so it does only demuxing and muxing. It is useful for changing the container format or modifying container-level metadata. The diagram above will, in this case, simplify to this:
_______              ______________            ________ |       |            |              |          |        | | input |  demuxer   | encoded data |  muxer   | output | | file  | ---------> | packets      | -------> | file   | |_______|            |______________|          |________|
Since there is no decoding or encoding, it is very fast and there is no quality loss. However, it might not work in some cases because of many factors. Applying filters is obviously also impossible, since filters work on uncompressed data.
ffmpeg provides the "-map" option for manual control of stream selection in each output file. Users can skip "-map" and let ffmpeg perform automatic stream selection as described below. The "-vn / -an / -sn / -dn" options can be used to skip inclusion of video, audio, subtitle and data streams respectively, whether manually mapped or automatically selected, except for those streams which are outputs of complex filtergraphs.
Description The sub-sections that follow describe the various rules that are involved in stream selection.  The examples that follow next show how these rules are applied in practice.
While every effort is made to accurately reflect the behavior of the program, FFmpeg is under continuous development and the code may have changed since the time of this writing.
Automatic stream selection
In the absence of any map options for a particular output file, ffmpeg inspects the output format to check which type of streams can be included in it, viz. video, audio and/or subtitles. For each acceptable stream type, ffmpeg will pick one stream, when available, from among all the inputs.
It will select that stream based upon the following criteria:
•   for video, it is the stream with the highest resolution,
•   for audio, it is the stream with the most channels,
•   for subtitles, it is the first subtitle stream found but there's a caveat.  The output format's default subtitle encoder can be either text-based or image-based, and only a subtitle stream of the same type will be chosen.
In the case where several streams of the same type rate equally, the stream with the lowest index is chosen.
Data or attachment streams are not automatically selected and can only be included using "-map".
Manual stream selection
When "-map" is used, only user-mapped streams are included in that output file, with one possible exception for filtergraph outputs described below.
If there are any complex filtergraph output streams with unlabeled pads, they will be added to the first output file. This will lead to a fatal error if the stream type is not supported by the output format. In the absence of the map option, the inclusion of these streams leads to the automatic stream selection of their types being skipped. If map options are present, these filtergraph streams are included in addition to the mapped streams.
Complex filtergraph output streams with labeled pads must be mapped once and exactly once.
Stream handling is independent of stream selection, with an exception for subtitles described below. Stream handling is set via the "-codec" option addressed to streams within a specific output file. In particular, codec options are applied by ffmpeg after the stream selection process and thus do not influence the latter. If no "-codec" option is specified for a stream type, ffmpeg will select the default encoder registered by the output file muxer.
An exception exists for subtitles. If a subtitle encoder is specified for an output file, the first subtitle stream found of any type, text or image, will be included. ffmpeg does not validate if the specified encoder can convert the selected stream or if the converted stream is acceptable within the output format. This applies generally as well: when the user sets an encoder manually, the stream selection process cannot check if the encoded stream can be muxed into the output file.  If it cannot, ffmpeg will abort and all output files will fail to be processed.
Examples The following examples illustrate the behavior, quirks and limitations of ffmpeg's stream selection methods.
They assume the following three input files.
input file 'A.avi' stream 0: video 640x360 stream 1: audio 2 channels
input file 'B.mp4' stream 0: video 1920x1080 stream 1: audio 2 channels stream 2: subtitles (text) stream 3: audio 5.1 channels stream 4: subtitles (text)
input file 'C.mkv' stream 0: video 1280x720 stream 1: audio 2 channels stream 2: subtitles (image)
Example: automatic stream selection
ffmpeg -i A.avi -i B.mp4 out1.mkv out2.wav -map 1:a -c:a copy out3.mov
There are three output files specified, and for the first two, no "-map" options are set, so ffmpeg will select streams for these two files automatically.
out1.mkv is a Matroska container file and accepts video, audio and subtitle streams, so ffmpeg will try to select one of each type.For video, it will select "stream 0" from B.mp4, which has the highest resolution among all the input video streams.For audio, it will select "stream 3" from B.mp4, since it has the greatest number of channels.For subtitles, it will select "stream 2" from B.mp4, which is the first subtitle stream from among A.avi and B.mp4.
out2.wav accepts only audio streams, so only "stream 3" from B.mp4 is selected.
For out3.mov, since a "-map" option is set, no automatic stream selection will occur. The "-map 1:a" option will select all audio streams from the second input B.mp4. No other streams will be included in this output file.
For the first two outputs, all included streams will be transcoded. The encoders chosen will be the default ones registered by each output format, which may not match the codec of the selected input streams.
For the third output, codec option for audio streams has been set to "copy", so no decoding-filtering-encoding operations will occur, or can occur.  Packets of selected streams shall be conveyed from the input file and muxed within the output file.
Example: automatic subtitles selection
ffmpeg -i C.mkv out1.mkv -c:s dvdsub -an out2.mkv
Although out1.mkv is a Matroska container file which accepts subtitle streams, only a video and audio stream shall be selected. The subtitle stream of C.mkv is image-based and the default subtitle encoder of the Matroska muxer is text-based, so a transcode operation for the subtitles is expected to fail and hence the stream isn't selected. However, in out2.mkv, a subtitle encoder is specified in the command and so, the subtitle stream is selected, in addition to the video stream. The presence of "-an" disables audio stream selection for out2.mkv.
Example: unlabeled filtergraph outputs
ffmpeg -i A.avi -i C.mkv -i B.mp4 -filter_complex "overlay" out1.mp4 out2.srt
A filtergraph is setup here using the "-filter_complex" option and consists of a single video filter. The "overlay" filter requires exactly two video inputs, but none are specified, so the first two available video streams are used, those of A.avi and C.mkv. The output pad of the filter has no label and so is sent to the first output file out1.mp4. Due to this, automatic selection of the video stream is skipped, which would have selected the stream in B.mp4. The audio stream with most channels viz. "stream 3" in B.mp4, is chosen automatically. No subtitle stream is chosen however, since the MP4 format has no default subtitle encoder registered, and the user hasn't specified a subtitle encoder.
The 2nd output file, out2.srt, only accepts text-based subtitle streams. So, even though the first subtitle stream available belongs to C.mkv, it is image-based and hence skipped.  The selected stream, "stream 2" in B.mp4, is the first text-based subtitle stream.
Example: labeled filtergraph outputs
ffmpeg -i A.avi -i B.mp4 -i C.mkv -filter_complex "[1:v]hue=s=0[outv];overlay;aresample" \ -map '[outv]' -an        out1.mp4 \ out2.mkv \ -map '[outv]' -map 1:a:0 out3.mkv
The above command will fail, as the output pad labelled "[outv]" has been mapped twice.  None of the output files shall be processed.
ffmpeg -i A.avi -i B.mp4 -i C.mkv -filter_complex "[1:v]hue=s=0[outv];overlay;aresample" \ -an        out1.mp4 \ out2.mkv \ -map 1:a:0 out3.mkv
This command above will also fail as the hue filter output has a label, "[outv]", and hasn't been mapped anywhere.
The command should be modified as follows,
ffmpeg -i A.avi -i B.mp4 -i C.mkv -filter_complex "[1:v]hue=s=0,split=2[outv1][outv2];overlay;aresample" \ -map '[outv1]' -an        out1.mp4 \ out2.mkv \ -map '[outv2]' -map 1:a:0 out3.mkv
The video stream from B.mp4 is sent to the hue filter, whose output is cloned once using the split filter, and both outputs labelled. Then a copy each is mapped to the first and third output files.
The overlay filter, requiring two video inputs, uses the first two unused video streams. Those are the streams from A.avi and C.mkv. The overlay output isn't labelled, so it is sent to the first output file out1.mp4, regardless of the presence of the "-map" option.
The aresample filter is sent the first unused audio stream, that of A.avi. Since this filter output is also unlabelled, it too is mapped to the first output file. The presence of "-an" only suppresses automatic or manual stream selection of audio streams, not outputs sent from filtergraphs. Both these mapped streams shall be ordered before the mapped stream in out1.mp4.
The video, audio and subtitle streams mapped to "out2.mkv" are entirely determined by automatic stream selection.
out3.mkv consists of the cloned video output from the hue filter and the first audio stream from B.mp4.
Main options -f fmt (input/output) Force input or output file format. The format is normally auto detected for input files and guessed from the file extension for output files, so this option is not needed in most cases.
-i url (input) input file url
-y (global) Overwrite output files without asking.
-n (global) Do not overwrite output files, and exit immediately if a specified output file already exists.
-stream_loop number (input) Set number of times input stream shall be looped. Loop 0 means no loop, loop -1 means infinite loop.
-c[:stream_specifier] codec (input/output,per-stream) -codec[:stream_specifier] codec (input/output,per-stream) Select an encoder (when used before an output file) or a decoder (when used before an input file) for one or more streams. codec is the name of a decoder/encoder or a special value "copy" (output only) to indicate that the stream is not to be re-encoded.
ffmpeg -i INPUT -map 0 -c:v libx264 -c:a copy OUTPUT
encodes all video streams with libx264 and copies all audio streams.
For each stream, the last matching "c" option is applied, so
ffmpeg -i INPUT -map 0 -c copy -c:v:1 libx264 -c:a:137 libvorbis OUTPUT
will copy all the streams except the second video, which will be encoded with libx264, and the 138th audio, which will be encoded with libvorbis.
-t duration (input/output) When used as an input option (before "-i"), limit the duration of data read from the input file.
When used as an output option (before an output url), stop writing the output after its duration reaches duration.
duration must be a time duration specification, see the Time duration section in the ffmpeg-utils(1) manual.
-to and -t are mutually exclusive and -t has priority.
-to position (input/output) Stop writing the output or reading the input at position.  position must be a time duration specification, see the Time duration section in the ffmpeg-utils(1) manual.
-fs limit_size (output) Set the file size limit, expressed in bytes. No further chunk of bytes is written after the limit is exceeded. The size of the output file is slightly more than the requested file size.
-ss position (input/output) When used as an input option (before "-i"), seeks in this input file to position. Note that in most formats it is not possible to seek exactly, so ffmpeg will seek to the closest seek point before position.  When transcoding and -accurate_seek is enabled (the default), this extra segment between the seek point and position will be decoded and discarded. When doing stream copy or when -noaccurate_seek is used, it will be preserved.
When used as an output option (before an output url), decodes but discards input until the timestamps reach position.
position must be a time duration specification, see the Time duration section in the ffmpeg-utils(1) manual.
-sseof position (input) Like the "-ss" option but relative to the "end of file". That is negative values are earlier in the file, 0 is at EOF.
-itsoffset offset (input) Set the input time offset.
offset must be a time duration specification, see the Time duration section in the ffmpeg-utils(1) manual.
The offset is added to the timestamps of the input files. Specifying a positive offset means that the corresponding streams are delayed by the time duration specified in offset.
-itsscale scale (input,per-stream) Rescale input timestamps. scale should be a floating point number.
-timestamp date (output) Set the recording timestamp in the container.
date must be a date specification, see the Date section in the ffmpeg-utils(1) manual.
-metadata[:metadata_specifier] key=value (output,per-metadata) Set a metadata key/value pair.
An optional metadata_specifier may be given to set metadata on streams, chapters or programs. See "-map_metadata" documentation for details.
This option overrides metadata set with "-map_metadata". It is also possible to delete metadata by using an empty value.
For example, for setting the title in the output file:
ffmpeg -i in.avi -metadata title="my title" out.flv
To set the language of the first audio stream:
ffmpeg -i INPUT -metadata:s:a:0 language=eng OUTPUT
-disposition[:stream_specifier] value (output,per-stream) Sets the disposition for a stream.
This option overrides the disposition copied from the input stream. It is also possible to delete the disposition by setting it to 0.
The following dispositions are recognized:
default dub original comment lyrics karaoke forced hearing_impaired visual_impaired clean_effects attached_pic captions descriptions dependent metadata
For example, to make the second audio stream the default stream:
ffmpeg -i in.mkv -c copy -disposition:a:1 default out.mkv
To make the second subtitle stream the default stream and remove the default disposition from the first subtitle stream:
ffmpeg -i in.mkv -c copy -disposition:s:0 0 -disposition:s:1 default out.mkv
To add an embedded cover/thumbnail:
ffmpeg -i in.mp4 -i IMAGE -map 0 -map 1 -c copy -c:v:1 png -disposition:v:1 attached_pic out.mp4
Not all muxers support embedded thumbnails, and those who do, only support a few formats, like JPEG or PNG.
-program [title=title:][program_num=program_num:]st=stream[:st=stream...] (output) Creates a program with the specified title, program_num and adds the specified stream(s) to it.
-target type (output) Specify target file type ("vcd", "svcd", "dvd", "dv", "dv50"). type may be prefixed with "pal-", "ntsc-" or "film-" to use the corresponding standard. All the format options (bitrate, codecs, buffer sizes) are then set automatically. You can just type:
ffmpeg -i myfile.avi -target vcd /tmp/vcd.mpg
Nevertheless you can specify additional options as long as you know they do not conflict with the standard, as in:
ffmpeg -i myfile.avi -target vcd -bf 2 /tmp/vcd.mpg
The parameters set for each target are as follows.
<pal>: -f vcd -muxrate 1411200 -muxpreload 0.44 -packetsize 2324 -s 352x288 -r 25 -codec:v mpeg1video -g 15 -b:v 1150k -maxrate:v 1150v -minrate:v 1150k -bufsize:v 327680 -ar 44100 -ac 2 -codec:a mp2 -b:a 224k
<ntsc>: -f vcd -muxrate 1411200 -muxpreload 0.44 -packetsize 2324 -s 352x240 -r 30000/1001 -codec:v mpeg1video -g 18 -b:v 1150k -maxrate:v 1150v -minrate:v 1150k -bufsize:v 327680 -ar 44100 -ac 2 -codec:a mp2 -b:a 224k
<film>: -f vcd -muxrate 1411200 -muxpreload 0.44 -packetsize 2324 -s 352x240 -r 24000/1001 -codec:v mpeg1video -g 18 -b:v 1150k -maxrate:v 1150v -minrate:v 1150k -bufsize:v 327680 -ar 44100 -ac 2 -codec:a mp2 -b:a 224k
SVCD
<pal>: -f svcd -packetsize 2324 -s 480x576 -pix_fmt yuv420p -r 25 -codec:v mpeg2video -g 15 -b:v 2040k -maxrate:v 2516k -minrate:v 0 -bufsize:v 1835008 -scan_offset 1 -ar 44100 -codec:a mp2 -b:a 224k
<ntsc>: -f svcd -packetsize 2324 -s 480x480 -pix_fmt yuv420p -r 30000/1001 -codec:v mpeg2video -g 18 -b:v 2040k -maxrate:v 2516k -minrate:v 0 -bufsize:v 1835008 -scan_offset 1 -ar 44100 -codec:a mp2 -b:a 224k
<film>: -f svcd -packetsize 2324 -s 480x480 -pix_fmt yuv420p -r 24000/1001 -codec:v mpeg2video -g 18 -b:v 2040k -maxrate:v 2516k -minrate:v 0 -bufsize:v 1835008 -scan_offset 1 -ar 44100 -codec:a mp2 -b:a 224k
<pal>: -f dvd -muxrate 10080k -packetsize 2048 -s 720x576 -pix_fmt yuv420p -r 25 -codec:v mpeg2video -g 15 -b:v 6000k -maxrate:v 9000k -minrate:v 0 -bufsize:v 1835008 -ar 48000 -codec:a ac3 -b:a 448k
<ntsc>: -f dvd -muxrate 10080k -packetsize 2048 -s 720x480 -pix_fmt yuv420p -r 30000/1001 -codec:v mpeg2video -g 18 -b:v 6000k -maxrate:v 9000k -minrate:v 0 -bufsize:v 1835008 -ar 48000 -codec:a ac3 -b:a 448k
<film>: -f dvd -muxrate 10080k -packetsize 2048 -s 720x480 -pix_fmt yuv420p -r 24000/1001 -codec:v mpeg2video -g 18 -b:v 6000k -maxrate:v 9000k -minrate:v 0 -bufsize:v 1835008 -ar 48000 -codec:a ac3 -b:a 448k
<pal>: -f dv -s 720x576 -pix_fmt yuv420p -r 25 -ar 48000 -ac 2
<ntsc>: -f dv -s 720x480 -pix_fmt yuv411p -r 30000/1001 -ar 48000 -ac 2
<film>: -f dv -s 720x480 -pix_fmt yuv411p -r 24000/1001 -ar 48000 -ac 2
The "dv50" target is identical to the "dv" target except that the pixel format set is "yuv422p" for all three standards.
Any user-set value for a parameter above will override the target preset value. In that case, the output may not comply with the target standard.
-dn (input/output) As an input option, blocks all data streams of a file from being filtered or being automatically selected or mapped for any output. See "-discard" option to disable streams individually.
As an output option, disables data recording i.e. automatic selection or mapping of any data stream. For full manual control see the "-map" option.
-dframes number (output) Set the number of data frames to output. This is an obsolete alias for "-frames:d", which you should use instead.
-frames[:stream_specifier] framecount (output,per-stream) Stop writing to the stream after framecount frames.
-q[:stream_specifier] q (output,per-stream) -qscale[:stream_specifier] q (output,per-stream) Use fixed quality scale (VBR). The meaning of q/qscale is codec- dependent.  If qscale is used without a stream_specifier then it applies only to the video stream, this is to maintain compatibility with previous behavior and as specifying the same codec specific value to 2 different codecs that is audio and video generally is not what is intended when no stream_specifier is used.
-filter[:stream_specifier] filtergraph (output,per-stream) Create the filtergraph specified by filtergraph and use it to filter the stream.
filtergraph is a description of the filtergraph to apply to the stream, and must have a single input and a single output of the same type of the stream. In the filtergraph, the input is associated to the label "in", and the output to the label "out". See the ffmpeg- filters manual for more information about the filtergraph syntax.
See the -filter_complex option if you want to create filtergraphs with multiple inputs and/or outputs.
-filter_script[:stream_specifier] filename (output,per-stream) This option is similar to -filter, the only difference is that its argument is the name of the file from which a filtergraph description is to be read.
-filter_threads nb_threads (global) Defines how many threads are used to process a filter pipeline. Each pipeline will produce a thread pool with this many threads available for parallel processing.  The default is the number of available CPUs.
-pre[:stream_specifier] preset_name (output,per-stream) Specify the preset for matching stream(s).
-stats (global) Print encoding progress/statistics. It is on by default, to explicitly disable it you need to specify "-nostats".
-stats_period time (global) Set period at which encoding progress/statistics are updated. Default is 0.5 seconds.
-progress url (global) Send program-friendly progress information to url.
Progress information is written periodically and at the end of the encoding process. It is made of "key=value" lines. key consists of only alphanumeric characters. The last key of a sequence of progress information is always "progress".
The update period is set using "-stats_period".
-stdin Enable interaction on standard input. On by default unless standard input is used as an input. To explicitly disable interaction you need to specify "-nostdin".
Disabling interaction on standard input is useful, for example, if ffmpeg is in the background process group. Roughly the same result can be achieved with "ffmpeg ... < /dev/null" but it requires a shell.
-debug_ts (global) Print timestamp information. It is off by default. This option is mostly useful for testing and debugging purposes, and the output format may change from one version to another, so it should not be employed by portable scripts.
See also the option "-fdebug ts".
-attach filename (output) Add an attachment to the output file. This is supported by a few formats like Matroska for e.g. fonts used in rendering subtitles. Attachments are implemented as a specific type of stream, so this option will add a new stream to the file. It is then possible to use per-stream options on this stream in the usual way. Attachment streams created with this option will be created after all the other streams (i.e. those created with "-map" or automatic mappings).
Note that for Matroska you also have to set the mimetype metadata tag:
ffmpeg -i INPUT -attach DejaVuSans.ttf -metadata:s:2 mimetype=application/x-truetype-font out.mkv
(assuming that the attachment stream will be third in the output file).
-dump_attachment[:stream_specifier] filename (input,per-stream) Extract the matching attachment stream into a file named filename. If filename is empty, then the value of the "filename" metadata tag will be used.
E.g. to extract the first attachment to a file named 'out.ttf':
ffmpeg -dump_attachment:t:0 out.ttf -i INPUT
To extract all attachments to files determined by the "filename" tag:
ffmpeg -dump_attachment:t "" -i INPUT
Technical note -- attachments are implemented as codec extradata, so this option can actually be used to extract extradata from any stream, not just attachments.
Video Options -vframes number (output) Set the number of video frames to output. This is an obsolete alias for "-frames:v", which you should use instead.
-r[:stream_specifier] fps (input/output,per-stream) Set frame rate (Hz value, fraction or abbreviation).
As an input option, ignore any timestamps stored in the file and instead generate timestamps assuming constant frame rate fps.  This is not the same as the -framerate option used for some input formats like image2 or v4l2 (it used to be the same in older versions of FFmpeg).  If in doubt use -framerate instead of the input option -r.
As an output option, duplicate or drop input frames to achieve constant output frame rate fps.
-fpsmax[:stream_specifier] fps (output,per-stream) Set maximum frame rate (Hz value, fraction or abbreviation).
Clamps output frame rate when output framerate is auto-set and is higher than this value.  Useful in batch processing or when input framerate is wrongly detected as very high.  It cannot be set together with "-r". It is ignored during streamcopy.
-s[:stream_specifier] size (input/output,per-stream) Set frame size.
As an input option, this is a shortcut for the video_size private option, recognized by some demuxers for which the frame size is either not stored in the file or is configurable -- e.g. raw video or video grabbers.
As an output option, this inserts the "scale" video filter to the end of the corresponding filtergraph. Please use the "scale" filter directly to insert it at the beginning or some other place.
The format is wxh (default - same as source).
-aspect[:stream_specifier] aspect (output,per-stream) Set the video display aspect ratio specified by aspect.
aspect can be a floating point number string, or a string of the form num:den, where num and den are the numerator and denominator of the aspect ratio. For example "4:3", "16:9", "1.3333", and "1.7777" are valid argument values.
If used together with -vcodec copy, it will affect the aspect ratio stored at container level, but not the aspect ratio stored in encoded frames, if it exists.
-vn (input/output) As an input option, blocks all video streams of a file from being filtered or being automatically selected or mapped for any output. See "-discard" option to disable streams individually.
As an output option, disables video recording i.e. automatic selection or mapping of any video stream. For full manual control see the "-map" option.
-vcodec codec (output) Set the video codec. This is an alias for "-codec:v".
-pass[:stream_specifier] n (output,per-stream) Select the pass number (1 or 2). It is used to do two-pass video encoding. The statistics of the video are recorded in the first pass into a log file (see also the option -passlogfile), and in the second pass that log file is used to generate the video at the exact requested bitrate.  On pass 1, you may just deactivate audio and set output to null, examples for Windows and Unix:
ffmpeg -i foo.mov -c:v libxvid -pass 1 -an -f rawvideo -y NUL ffmpeg -i foo.mov -c:v libxvid -pass 1 -an -f rawvideo -y /dev/null
-passlogfile[:stream_specifier] prefix (output,per-stream) Set two-pass log file name prefix to prefix, the default file name prefix is ``ffmpeg2pass''. The complete file name will be PREFIX-N.log, where N is a number specific to the output stream
-vf filtergraph (output) Create the filtergraph specified by filtergraph and use it to filter the stream.
This is an alias for "-filter:v", see the -filter option.
-autorotate Automatically rotate the video according to file metadata. Enabled by default, use -noautorotate to disable it.
-autoscale Automatically scale the video according to the resolution of first frame.  Enabled by default, use -noautoscale to disable it. When autoscale is disabled, all output frames of filter graph might not be in the same resolution and may be inadequate for some encoder/muxer. Therefore, it is not recommended to disable it unless you really know what you are doing.  Disable autoscale at your own risk.
Advanced Video options -pix_fmt[:stream_specifier] format (input/output,per-stream) Set pixel format. Use "-pix_fmts" to show all the supported pixel formats.  If the selected pixel format can not be selected, ffmpeg will print a warning and select the best pixel format supported by the encoder.  If pix_fmt is prefixed by a "+", ffmpeg will exit with an error if the requested pixel format can not be selected, and automatic conversions inside filtergraphs are disabled.  If pix_fmt is a single "+", ffmpeg selects the same pixel format as the input (or graph output) and automatic conversions are disabled.
-sws_flags flags (input/output) Set SwScaler flags.
-rc_override[:stream_specifier] override (output,per-stream) Rate control override for specific intervals, formatted as "int,int,int" list separated with slashes. Two first values are the beginning and end frame numbers, last one is quantizer to use if positive, or quality factor if negative.
-ilme Force interlacing support in encoder (MPEG-2 and MPEG-4 only).  Use this option if your input file is interlaced and you want to keep the interlaced format for minimum losses.  The alternative is to deinterlace the input stream by use of a filter such as "yadif" or "bwdif", but deinterlacing introduces losses.
-psnr Calculate PSNR of compressed frames.
-vstats Dump video coding statistics to vstats_HHMMSS.log.
-vstats_file file Dump video coding statistics to file.
-vstats_version file Specifies which version of the vstats format to use. Default is 2.
version = 1 :
"frame= %5d q= %2.1f PSNR= %6.2f f_size= %6d s_size= %8.0fkB time= %0.3f br= %7.1fkbits/s avg_br= %7.1fkbits/s"
version > 1:
"out= %2d st= %2d frame= %5d q= %2.1f PSNR= %6.2f f_size= %6d s_size= %8.0fkB time= %0.3f br= %7.1fkbits/s avg_br= %7.1fkbits/s"
-top[:stream_specifier] n (output,per-stream) top=1/bottom=0/auto=-1 field first
-dc precision Intra_dc_precision.
-vtag fourcc/tag (output) Force video tag/fourcc. This is an alias for "-tag:v".
-qphist (global) Show QP histogram
-vbsf bitstream_filter Deprecated see -bsf
-force_key_frames[:stream_specifier] time[,time...] (output,per-stream) -force_key_frames[:stream_specifier] expr:expr (output,per-stream) -force_key_frames[:stream_specifier] source (output,per-stream) force_key_frames can take arguments of the following form:
time[,time...] If the argument consists of timestamps, ffmpeg will round the specified times to the nearest output timestamp as per the encoder time base and force a keyframe at the first frame having timestamp equal or greater than the computed timestamp. Note that if the encoder time base is too coarse, then the keyframes may be forced on frames with timestamps lower than the specified time. The default encoder time base is the inverse of the output framerate but may be set otherwise via "-enc_time_base".
If one of the times is ""chapters"[delta]", it is expanded into the time of the beginning of all chapters in the file, shifted by delta, expressed as a time in seconds.  This option can be useful to ensure that a seek point is present at a chapter mark or any other designated place in the output file.
For example, to insert a key frame at 5 minutes, plus key frames 0.1 second before the beginning of every chapter:
-force_key_frames 0:05:00,chapters-0.1
expr:expr If the argument is prefixed with "expr:", the string expr is interpreted like an expression and is evaluated for each frame. A key frame is forced in case the evaluation is non-zero.
The expression in expr can contain the following constants:
n   the number of current processed frame, starting from 0
n_forced the number of forced frames
prev_forced_n the number of the previous forced frame, it is "NAN" when no keyframe was forced yet
prev_forced_t the time of the previous forced frame, it is "NAN" when no keyframe was forced yet
t   the time of the current processed frame
For example to force a key frame every 5 seconds, you can specify:
-force_key_frames expr:gte(t,n_forced*5)
To force a key frame 5 seconds after the time of the last forced one, starting from second 13:
-force_key_frames expr:if(isnan(prev_forced_t),gte(t,13),gte(t,prev_forced_t+5))
source If the argument is "source", ffmpeg will force a key frame if the current frame being encoded is marked as a key frame in its source.
Note that forcing too many keyframes is very harmful for the lookahead algorithms of certain encoders: using fixed-GOP options or similar would be more efficient.
-copyinkf[:stream_specifier] (output,per-stream) When doing stream copy, copy also non-key frames found at the beginning.
-init_hw_device type[=name][:device[,key=value...]] Initialise a new hardware device of type type called name, using the given device parameters.  If no name is specified it will receive a default name of the form "type%d".
The meaning of device and the following arguments depends on the device type:
cuda device is the number of the CUDA device.
dxva2 device is the number of the Direct3D 9 display adapter.
vaapi device is either an X11 display name or a DRM render node.  If not specified, it will attempt to open the default X11 display ($DISPLAY) and then the first DRM render node (/dev/dri/renderD128).
vdpau device is an X11 display name.  If not specified, it will attempt to open the default X11 display ($DISPLAY).
qsv device selects a value in MFX_IMPL_*. Allowed values are:
auto sw hw auto_any hw_any hw2 hw3 hw4
If not specified, auto_any is used.  (Note that it may be easier to achieve the desired result for QSV by creating the platform- appropriate subdevice (dxva2 or vaapi) and then deriving a QSV device from that.)
opencl device selects the platform and device as platform_index.device_index.
The set of devices can also be filtered using the key-value pairs to find only devices matching particular platform or device strings.
The strings usable as filters are:
platform_profile platform_version platform_name platform_vendor platform_extensions device_name device_vendor driver_version device_version device_profile device_extensions device_type
The indices and filters must together uniquely select a device.
-init_hw_device opencl:0.1 Choose the second device on the first platform.
-init_hw_device opencl:,device_name=Foo9000 Choose the device with a name containing the string Foo9000.
-init_hw_device opencl:1,device_type=gpu,device_extensions=cl_khr_fp16 Choose the GPU device on the second platform supporting the cl_khr_fp16 extension.
vulkan If device is an integer, it selects the device by its index in a system-dependent list of devices.  If device is any other string, it selects the first device with a name containing that string as a substring.
debug If set to 1, enables the validation layer, if installed.
linear_images If set to 1, images allocated by the hwcontext will be linear and locally mappable.
instance_extensions A plus separated list of additional instance extensions to enable.
device_extensions A plus separated list of additional device extensions to enable.
-init_hw_device vulkan:1 Choose the second device on the system.
-init_hw_device vulkan:RADV Choose the first device with a name containing the string RADV.
-init_hw_device vulkan:0,instance_extensions=VK_KHR_wayland_surface+VK_KHR_xcb_surface Choose the first device and enable the Wayland and XCB instance extensions.
-init_hw_device type[=name]@source Initialise a new hardware device of type type called name, deriving it from the existing device with the name source.
-init_hw_device list List all hardware device types supported in this build of ffmpeg.
-filter_hw_device name Pass the hardware device called name to all filters in any filter graph.  This can be used to set the device to upload to with the "hwupload" filter, or the device to map to with the "hwmap" filter. Other filters may also make use of this parameter when they require a hardware device.  Note that this is typically only required when the input is not already in hardware frames - when it is, filters will derive the device they require from the context of the frames they receive as input.
This is a global setting, so all filters will receive the same device.
-hwaccel[:stream_specifier] hwaccel (input,per-stream) Use hardware acceleration to decode the matching stream(s). The allowed values of hwaccel are:
none Do not use any hardware acceleration (the default).
auto Automatically select the hardware acceleration method.
vdpau Use VDPAU (Video Decode and Presentation API for Unix) hardware acceleration.
dxva2 Use DXVA2 (DirectX Video Acceleration) hardware acceleration.
vaapi Use VAAPI (Video Acceleration API) hardware acceleration.
qsv Use the Intel QuickSync Video acceleration for video transcoding.
Unlike most other values, this option does not enable accelerated decoding (that is used automatically whenever a qsv decoder is selected), but accelerated transcoding, without copying the frames into the system memory.
For it to work, both the decoder and the encoder must support QSV acceleration and no filters must be used.
This option has no effect if the selected hwaccel is not available or not supported by the chosen decoder.
Note that most acceleration methods are intended for playback and will not be faster than software decoding on modern CPUs. Additionally, ffmpeg will usually need to copy the decoded frames from the GPU memory into the system memory, resulting in further performance loss. This option is thus mainly useful for testing.
-hwaccel_device[:stream_specifier] hwaccel_device (input,per-stream) Select a device to use for hardware acceleration.
This option only makes sense when the -hwaccel option is also specified.  It can either refer to an existing device created with -init_hw_device by name, or it can create a new device as if -init_hw_device type:hwaccel_device were called immediately before.
-hwaccels List all hardware acceleration methods supported in this build of ffmpeg.
Audio Options -aframes number (output) Set the number of audio frames to output. This is an obsolete alias for "-frames:a", which you should use instead.
-ar[:stream_specifier] freq (input/output,per-stream) Set the audio sampling frequency. For output streams it is set by default to the frequency of the corresponding input stream. For input streams this option only makes sense for audio grabbing devices and raw demuxers and is mapped to the corresponding demuxer options.
-aq q (output) Set the audio quality (codec-specific, VBR). This is an alias for -q:a.
-ac[:stream_specifier] channels (input/output,per-stream) Set the number of audio channels. For output streams it is set by default to the number of input audio channels. For input streams this option only makes sense for audio grabbing devices and raw demuxers and is mapped to the corresponding demuxer options.
-an (input/output) As an input option, blocks all audio streams of a file from being filtered or being automatically selected or mapped for any output. See "-discard" option to disable streams individually.
As an output option, disables audio recording i.e. automatic selection or mapping of any audio stream. For full manual control see the "-map" option.
-acodec codec (input/output) Set the audio codec. This is an alias for "-codec:a".
-sample_fmt[:stream_specifier] sample_fmt (output,per-stream) Set the audio sample format. Use "-sample_fmts" to get a list of supported sample formats.
-af filtergraph (output) Create the filtergraph specified by filtergraph and use it to filter the stream.
This is an alias for "-filter:a", see the -filter option.
Advanced Audio options -atag fourcc/tag (output) Force audio tag/fourcc. This is an alias for "-tag:a".
-absf bitstream_filter Deprecated, see -bsf
-guess_layout_max channels (input,per-stream) If some input channel layout is not known, try to guess only if it corresponds to at most the specified number of channels. For example, 2 tells to ffmpeg to recognize 1 channel as mono and 2 channels as stereo but not 6 channels as 5.1. The default is to always try to guess. Use 0 to disable all guessing.
Subtitle options -scodec codec (input/output) Set the subtitle codec. This is an alias for "-codec:s".
-sn (input/output) As an input option, blocks all subtitle streams of a file from being filtered or being automatically selected or mapped for any output. See "-discard" option to disable streams individually.
As an output option, disables subtitle recording i.e. automatic selection or mapping of any subtitle stream. For full manual control see the "-map" option.
-sbsf bitstream_filter Deprecated, see -bsf
Advanced Subtitle options -fix_sub_duration Fix subtitles durations. For each subtitle, wait for the next packet in the same stream and adjust the duration of the first to avoid overlap. This is necessary with some subtitles codecs, especially DVB subtitles, because the duration in the original packet is only a rough estimate and the end is actually marked by an empty subtitle frame. Failing to use this option when necessary can result in exaggerated durations or muxing failures due to non-monotonic timestamps.
Note that this option will delay the output of all data until the next subtitle packet is decoded: it may increase memory consumption and latency a lot.
-canvas_size size Set the size of the canvas used to render subtitles.
Advanced options -map [-]input_file_id[:stream_specifier][?][,sync_file_id[:stream_specifier]] | [linklabel] (output) Designate one or more input streams as a source for the output file. Each input stream is identified by the input file index input_file_id and the input stream index input_stream_id within the input file. Both indices start at 0. If specified, sync_file_id:stream_specifier sets which input stream is used as a presentation sync reference.