avconv reads from an arbitrary number of input "files" (which can be regular
files, pipes, network streams, grabbing devices, etc.), specified by the
@code{-i} option, and writes to an arbitrary number of output "files", which are
-specified by a plain output filename. Anything found on the commandline which
+specified by a plain output filename. Anything found on the command line which
cannot be interpreted as an option is considered to be an output filename.
Each input or output file can in principle contain any number of streams of
@c man end DESCRIPTION
+@chapter Detailed description
+@c man begin DETAILED DESCRIPTION
+
+The transcoding process in @command{avconv} for each output can be described by
+the following diagram:
+
+@example
+ _______ ______________ _________ ______________ ________
+| | | | | | | | | |
+| input | demuxer | encoded data | decoder | decoded | encoder | encoded data | muxer | output |
+| file | ---------> | packets | ---------> | frames | ---------> | packets | -------> | file |
+|_______| |______________| |_________| |______________| |________|
+
+@end example
+
+@command{avconv} calls the libavformat library (containing demuxers) to read
+input files and get packets containing encoded data from them. When there are
+multiple input files, @command{avconv} 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 again. Finally those are
+passed to the muxer, which writes the encoded packets to the output file.
+
+@section Filtering
+Before encoding, @command{avconv} can process raw audio and video frames using
+filters from the libavfilter library. Several chained filters form a filter
+graph. @command{avconv} distinguishes between two types of filtergraphs -
+simple and complex.
+
+@subsection 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:
+
+@example
+ _________ __________ ______________
+| | | | | |
+| decoded | simple filtergraph | filtered | encoder | encoded data |
+| frames | -------------------> | frames | ---------> | packets |
+|_________| |__________| |______________|
+
+@end example
+
+Simple filtergraphs are configured with the per-stream @option{-filter} option
+(with @option{-vf} and @option{-af} aliases for video and audio respectively).
+A simple filtergraph for video can look for example like this:
+
+@example
+ _______ _____________ _______ _____ ________
+| | | | | | | | | |
+| input | ---> | deinterlace | ---> | scale | ---> | fps | ---> | output |
+|_______| |_____________| |_______| |_____| |________|
+
+@end example
+
+Note that some filters change frame properties but not frame contents. E.g. the
+@code{fps} filter in the example above changes number of frames, but does not
+touch the frame contents. Another example is the @code{setpts} filter, which
+only sets timestamps and otherwise passes the frames unchanged.
+
+@subsection Complex filtergraphs
+Complex filtergraphs are those which cannot be described as simply a linear
+processing chain applied to one stream. This is the case e.g. 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:
+
+@example
+ _________
+| |
+| input 0 |\ __________
+|_________| \ | |
+ \ _________ /| output 0 |
+ \ | | / |__________|
+ _________ \| complex | /
+| | | |/
+| input 1 |---->| filter |\
+|_________| | | \ __________
+ /| graph | \ | |
+ / | | \| output 1 |
+ _________ / |_________| |__________|
+| | /
+| input 2 |/
+|_________|
+
+@end example
+
+Complex filtergraphs are configured with the @option{-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.
+
+A trivial example of a complex filtergraph is the @code{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 @code{amix} filter.
+
+@section Stream copy
+Stream copy is a mode selected by supplying the @code{copy} parameter to the
+@option{-codec} option. It makes @command{avconv} 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:
+
+@example
+ _______ ______________ ________
+| | | | | |
+| input | demuxer | encoded data | muxer | output |
+| file | ---------> | packets | -------> | file |
+|_______| |______________| |________|
+
+@end example
+
+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.
+
+@c man end DETAILED DESCRIPTION
+
@chapter Stream selection
@c man begin STREAM SELECTION
avconv -i in.avi -metadata title="my title" out.flv
@end example
-To set the language of the second stream:
+To set the language of the first audio stream:
@example
-avconv -i INPUT -metadata:s:1 language=eng OUTPUT
+avconv -i INPUT -metadata:s:a:0 language=eng OUTPUT
@end example
@item -target @var{type} (@emph{output})
@var{filter_graph} is a description of the filter graph to apply to
the stream. Use @code{-filters} to show all the available filters
(including also sources and sinks).
+
+See also the @option{-filter_complex} option if you want to create filter graphs
+with multiple inputs and/or outputs.
@item -pre[:@var{stream_specifier}] @var{preset_name} (@emph{output,per-stream})
Specify the preset for matching stream(s).
@item -vframes @var{number} (@emph{output})
Set the number of video frames to record. This is an alias for @code{-frames:v}.
@item -r[:@var{stream_specifier}] @var{fps} (@emph{input/output,per-stream})
-Set frame rate (Hz value, fraction or abbreviation), (default = 25).
+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 @var{fps}.
+
+As an output option, duplicate or drop input frames to achieve constant output
+frame rate @var{fps} (note that this actually causes the @code{fps} filter to be
+inserted to the end of the corresponding filtergraph).
+
@item -s[:@var{stream_specifier}] @var{size} (@emph{input/output,per-stream})
-Set frame size. The format is @samp{wxh} (default - same as source).
-The following abbreviations are recognized:
+Set frame size.
+
+As an input option, this is a shortcut for the @option{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 @code{scale} video filter to the
+@emph{end} of the corresponding filtergraph. Please use the @code{scale} filter
+directly to insert it at the beginning or some other place.
+
+The format is @samp{wxh} (default - same as source). The following
+abbreviations are recognized:
@table @samp
@item sqcif
128x96
@item -vn (@emph{output})
Disable video recording.
-@item -bt @var{tolerance}
-Set video bitrate tolerance (in bits, default 4000k).
-Has a minimum value of: (target_bitrate/target_framerate).
-In 1-pass mode, bitrate tolerance specifies how far ratecontrol is
-willing to deviate from the target average bitrate value. This is
-not related to min/max bitrate. Lowering tolerance too much has
-an adverse effect on quality.
-@item -maxrate @var{bitrate}
-Set max video bitrate (in bit/s).
-Requires -bufsize to be set.
-@item -minrate @var{bitrate}
-Set min video bitrate (in bit/s).
-Most useful in setting up a CBR encode:
-@example
-avconv -i myfile.avi -b 4000k -minrate 4000k -maxrate 4000k -bufsize 1835k out.m2v
-@end example
-It is of little use elsewise.
-@item -bufsize @var{size}
-Set video buffer verifier buffer size (in bits).
+
@item -vcodec @var{codec} (@emph{output})
Set the video codec. This is an alias for @code{-codec:v}.
-@item -same_quant
-Use same quantizer as source (implies VBR).
-Note that this is NOT SAME QUALITY. Do not use this option unless you know you
-need it.
-
-@item -pass @var{n}
+@item -pass[:@var{stream_specifier}] @var{n} (@emph{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),
avconv -i foo.mov -c:v libxvid -pass 1 -an -f rawvideo -y /dev/null
@end example
-@item -passlogfile @var{prefix} (@emph{global})
+@item -passlogfile[:@var{stream_specifier}] @var{prefix} (@emph{output,per-stream})
Set two-pass log file name prefix to @var{prefix}, the default file name
prefix is ``av2pass''. The complete file name will be
@file{PREFIX-N.log}, where N is a number specific to the output
pixel formats.
@item -sws_flags @var{flags} (@emph{input/output})
Set SwScaler flags.
-@item -g @var{gop_size}
-Set the group of pictures size.
@item -vdt @var{n}
Discard threshold.
-@item -qmin @var{q}
-minimum video quantizer scale (VBR)
-@item -qmax @var{q}
-maximum video quantizer scale (VBR)
-@item -qdiff @var{q}
-maximum difference between the quantizer scales (VBR)
-@item -qblur @var{blur}
-video quantizer scale blur (VBR) (range 0.0 - 1.0)
-@item -qcomp @var{compression}
-video quantizer scale compression (VBR) (default 0.5).
-Constant of ratecontrol equation. Recommended range for default rc_eq: 0.0-1.0
-
-@item -lmin @var{lambda}
-minimum video lagrange factor (VBR)
-@item -lmax @var{lambda}
-max video lagrange factor (VBR)
-@item -mblmin @var{lambda}
-minimum macroblock quantizer scale (VBR)
-@item -mblmax @var{lambda}
-maximum macroblock quantizer scale (VBR)
-
-These four options (lmin, lmax, mblmin, mblmax) use 'lambda' units,
-but you may use the QP2LAMBDA constant to easily convert from 'q' units:
-@example
-avconv -i src.ext -lmax 21*QP2LAMBDA dst.ext
-@end example
-
-@item -rc_init_cplx @var{complexity}
-initial complexity for single pass encoding
-@item -b_qfactor @var{factor}
-qp factor between P- and B-frames
-@item -i_qfactor @var{factor}
-qp factor between P- and I-frames
-@item -b_qoffset @var{offset}
-qp offset between P- and B-frames
-@item -i_qoffset @var{offset}
-qp offset between P- and I-frames
-@item -rc_eq @var{equation}
-Set rate control equation (see section "Expression Evaluation")
-(default = @code{tex^qComp}).
-
-When computing the rate control equation expression, besides the
-standard functions defined in the section "Expression Evaluation", the
-following functions are available:
-@table @var
-@item bits2qp(bits)
-@item qp2bits(qp)
-@end table
-
-and the following constants are available:
-@table @var
-@item iTex
-@item pTex
-@item tex
-@item mv
-@item fCode
-@item iCount
-@item mcVar
-@item var
-@item isI
-@item isP
-@item isB
-@item avgQP
-@item qComp
-@item avgIITex
-@item avgPITex
-@item avgPPTex
-@item avgBPTex
-@item avgTex
-@end table
@item -rc_override[:@var{stream_specifier}] @var{override} (@emph{output,per-stream})
rate control override for specific intervals
-@item -me_method @var{method}
-Set motion estimation method to @var{method}.
-Available methods are (from lowest to best quality):
-@table @samp
-@item zero
-Try just the (0, 0) vector.
-@item phods
-@item log
-@item x1
-@item hex
-@item umh
-@item epzs
-(default method)
-@item full
-exhaustive search (slow and marginally better than epzs)
-@end table
-
-@item -er @var{n}
-Set error resilience to @var{n}.
-@table @samp
-@item 1
-FF_ER_CAREFUL (default)
-@item 2
-FF_ER_COMPLIANT
-@item 3
-FF_ER_AGGRESSIVE
-@item 4
-FF_ER_VERY_AGGRESSIVE
-@end table
-
-@item -ec @var{bit_mask}
-Set error concealment to @var{bit_mask}. @var{bit_mask} is a bit mask of
-the following values:
-@table @samp
-@item 1
-FF_EC_GUESS_MVS (default = enabled)
-@item 2
-FF_EC_DEBLOCK (default = enabled)
-@end table
-
-@item -bf @var{frames}
-Use 'frames' B-frames (supported for MPEG-1, MPEG-2 and MPEG-4).
-@item -mbd @var{mode}
-macroblock decision
-@table @samp
-@item 0
-FF_MB_DECISION_SIMPLE: Use mb_cmp (cannot change it yet in avconv).
-@item 1
-FF_MB_DECISION_BITS: Choose the one which needs the fewest bits.
-@item 2
-FF_MB_DECISION_RD: rate distortion
-@end table
-
-@item -bug @var{param}
-Work around encoder bugs that are not auto-detected.
-@item -strict @var{strictness}
-How strictly to follow the standards.
@item -deinterlace
Deinterlace pictures.
+This option is deprecated since the deinterlacing is very low quality.
+Use the yadif filter with @code{-filter:v yadif}.
@item -vstats
Dump video coding statistics to @file{vstats_HHMMSS.log}.
@item -vstats_file @var{file}
@item -sample_fmt[:@var{stream_specifier}] @var{sample_fmt} (@emph{output,per-stream})
Set the audio sample format. Use @code{-sample_fmts} to get a list
of supported sample formats.
+@item -af @var{filter_graph} (@emph{output})
+@var{filter_graph} is a description of the filter graph to apply to
+the input audio.
+Use the option "-filters" to show all the available filters (including
+also sources and sinks). This is an alias for @code{-filter:a}.
@end table
@section Advanced Audio options:
@table @option
@item -atag @var{fourcc/tag} (@emph{output})
Force audio tag/fourcc. This is an alias for @code{-tag:a}.
-@item -audio_service_type @var{type}
-Set the type of service that the audio stream contains.
-@table @option
-@item ma
-Main Audio Service (default)
-@item ef
-Effects
-@item vi
-Visually Impaired
-@item hi
-Hearing Impaired
-@item di
-Dialogue
-@item co
-Commentary
-@item em
-Emergency
-@item vo
-Voice Over
-@item ka
-Karaoke
-@end table
@end table
@section Subtitle options:
Disable subtitle recording.
@end table
-@section Audio/Video grab options
-
-@table @option
-@item -isync (@emph{global})
-Synchronize read on input.
-@end table
-
@section Advanced options
@table @option
-@item -map [-]@var{input_file_id}[:@var{stream_specifier}][,@var{sync_file_id}[:@var{stream_specifier}]] (@emph{output})
+@item -map [-]@var{input_file_id}[:@var{stream_specifier}][,@var{sync_file_id}[:@var{stream_specifier}]] | @var{[linklabel]} (@emph{output})
Designate one or more input streams as a source for the output file. Each input
stream is identified by the input file index @var{input_file_id} and
A @code{-} character before the stream identifier creates a "negative" mapping.
It disables matching streams from already created mappings.
+An alternative @var{[linklabel]} form will map outputs from complex filter
+graphs (see the @option{-filter_complex} option) to the output file.
+@var{linklabel} must correspond to a defined output link label in the graph.
+
For example, to map ALL streams from the first input file to output
@example
avconv -i INPUT -map 0 output
Note that using this option disables the default mappings for this output file.
-@item -map_metadata[:@var{metadata_type}][:@var{index}] @var{infile}[:@var{metadata_type}][:@var{index}] (@emph{output,per-metadata})
+@item -map_metadata[:@var{metadata_spec_out}] @var{infile}[:@var{metadata_spec_in}] (@emph{output,per-metadata})
Set metadata information of the next output file from @var{infile}. Note that
those are file indices (zero-based), not filenames.
-Optional @var{metadata_type} parameters specify, which metadata to copy - (g)lobal
-(i.e. metadata that applies to the whole file), per-(s)tream, per-(c)hapter or
-per-(p)rogram. All metadata specifiers other than global must be followed by the
-stream/chapter/program index. If metadata specifier is omitted, it defaults to
-global.
+Optional @var{metadata_spec_in/out} parameters specify, which metadata to copy.
+A metadata specifier can have the following forms:
+@table @option
+@item @var{g}
+global metadata, i.e. metadata that applies to the whole file
+
+@item @var{s}[:@var{stream_spec}]
+per-stream metadata. @var{stream_spec} is a stream specifier as described
+in the @ref{Stream specifiers} chapter. In an input metadata specifier, the first
+matching stream is copied from. In an output metadata specifier, all matching
+streams are copied to.
+
+@item @var{c}:@var{chapter_index}
+per-chapter metadata. @var{chapter_index} is the zero-based chapter index.
+
+@item @var{p}:@var{program_index}
+per-program metadata. @var{program_index} is the zero-based program index.
+@end table
+If metadata specifier is omitted, it defaults to global.
By default, global metadata is copied from the first input file,
per-stream and per-chapter metadata is copied along with streams/chapters. These
@example
avconv -i in.ogg -map_metadata 0:s:0 out.mp3
@end example
+
+To do the reverse, i.e. copy global metadata to all audio streams:
+@example
+avconv -i in.mkv -map_metadata:s:a 0:g out.mkv
+@end example
+Note that simple @code{0} would work as well in this example, since global
+metadata is assumed by default.
+
@item -map_chapters @var{input_file_index} (@emph{output})
Copy chapters from input file with index @var{input_file_index} to the next
output file. If no chapter mapping is specified, then chapters are copied from
Dump each input packet to stderr.
@item -hex (@emph{global})
When dumping packets, also dump the payload.
-@item -ps @var{size}
-Set RTP payload size in bytes.
@item -re (@emph{input})
Read input at native frame rate. Mainly used to simulate a grab device.
-@item -threads @var{count}
-Thread count.
@item -vsync @var{parameter}
Video sync method.
@table @option
-@item 0
+@item passthrough
Each frame is passed with its timestamp from the demuxer to the muxer.
-@item 1
+@item cfr
Frames will be duplicated and dropped to achieve exactly the requested
constant framerate.
-@item 2
+@item vfr
Frames are passed through with their timestamp or dropped so as to
prevent 2 frames from having the same timestamp.
-@item -1
+@item auto
Chooses between 1 and 2 depending on muxer capabilities. This is the
default method.
@end table
the parameter is the maximum samples per second by which the audio is changed.
-async 1 is a special case where only the start of the audio stream is corrected
without any later correction.
+This option has been deprecated. Use the @code{asyncts} audio filter instead.
@item -copyts
Copy timestamps from input to output.
@item -copytb
Copy input stream time base from input to output when stream copying.
-@item -shortest
+@item -shortest (@emph{output})
Finish encoding when the shortest input stream ends.
@item -dts_delta_threshold
Timestamp discontinuity delta threshold.
a comma-separated list of bitstream filters. Use the @code{-bsfs} option
to get the list of bitstream filters.
@example
-avconv -i h264.mp4 -c:v copy -vbsf h264_mp4toannexb -an out.h264
+avconv -i h264.mp4 -c:v copy -bsf:v h264_mp4toannexb -an out.h264
@end example
@example
-avconv -i file.mov -an -vn -sbsf mov2textsub -c:s copy -f rawvideo sub.txt
+avconv -i file.mov -an -vn -bsf:s mov2textsub -c:s copy -f rawvideo sub.txt
@end example
@item -tag[:@var{stream_specifier}] @var{codec_tag} (@emph{output,per-stream})
Force a tag/fourcc for matching streams.
+
+@item -cpuflags mask (@emph{global})
+Set a mask that's applied to autodetected CPU flags. This option is intended
+for testing. Do not use it unless you know what you're doing.
+
+@item -filter_complex @var{filtergraph} (@emph{global})
+Define a complex filter graph, i.e. one with arbitrary number of inputs and/or
+outputs. For simple graphs -- those with one input and one output of the same
+type -- see the @option{-filter} options. @var{filtergraph} is a description of
+the filter graph, as described in @ref{Filtergraph syntax}.
+
+Input link labels must refer to input streams using the
+@code{[file_index:stream_specifier]} syntax (i.e. the same as @option{-map}
+uses). If @var{stream_specifier} matches multiple streams, the first one will be
+used. An unlabeled input will be connected to the first unused input stream of
+the matching type.
+
+Output link labels are referred to with @option{-map}. Unlabeled outputs are
+added to the first output file.
+
+Note that with this option it is possible to use only lavfi sources without
+normal input files.
+
+For example, to overlay an image over video
+@example
+avconv -i video.mkv -i image.png -filter_complex '[0:v][1:v]overlay[out]' -map
+'[out]' out.mkv
+@end example
+Here @code{[0:v]} refers to the first video stream in the first input file,
+which is linked to the first (main) input of the overlay filter. Similarly the
+first video stream in the second input is linked to the second (overlay) input
+of overlay.
+
+Assuming there is only one video stream in each input file, we can omit input
+labels, so the above is equivalent to
+@example
+avconv -i video.mkv -i image.png -filter_complex 'overlay[out]' -map
+'[out]' out.mkv
+@end example
+
+Furthermore we can omit the output label and the single output from the filter
+graph will be added to the output file automatically, so we can simply write
+@example
+avconv -i video.mkv -i image.png -filter_complex 'overlay' out.mkv
+@end example
+
+To generate 5 seconds of pure red video using lavfi @code{color} source:
+@example
+avconv -filter_complex 'color=red' -t 5 out.mkv
+@end example
@end table
@c man end OPTIONS
@item
If your computer is not fast enough, you can speed up the
compression at the expense of the compression ratio. You can use
-'-me zero' to speed up motion estimation, and '-intra' to disable
+'-me zero' to speed up motion estimation, and '-g 0' to disable
motion estimation completely (you have only I-frames, which means it
is about as good as JPEG compression).
The resulting output file @file{test12.avi} will contain first four streams from
the input file in reverse order.
+@item
+To force CBR video output:
+@example
+avconv -i myfile.avi -b 4000k -minrate 4000k -maxrate 4000k -bufsize 1835k out.m2v
+@end example
+
+@item
+The four options lmin, lmax, mblmin and mblmax use 'lambda' units,
+but you may use the QP2LAMBDA constant to easily convert from 'q' units:
+@example
+avconv -i src.ext -lmax 21*QP2LAMBDA dst.ext
+@end example
+
@end itemize
@c man end EXAMPLES
projects / ffmpeg / blobdiff