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Diffstat (limited to 'ffmpeg/doc/ffmpeg.texi')
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1 files changed, 168 insertions, 56 deletions
diff --git a/ffmpeg/doc/ffmpeg.texi b/ffmpeg/doc/ffmpeg.texi index ca5d652..0a930ce 100644 --- a/ffmpeg/doc/ffmpeg.texi +++ b/ffmpeg/doc/ffmpeg.texi @@ -16,26 +16,26 @@ ffmpeg [@var{global_options}] @{[@var{input_file_options}] -i @file{input_file}@ @chapter Description @c man begin DESCRIPTION -ffmpeg is a very fast video and audio converter that can also grab from +@command{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 +@command{ffmpeg} 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 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 -different types (video/audio/subtitle/attachment/data). Allowed number and/or -types of streams can be limited by the container format. Selecting, which -streams from which inputs go into output, is done either automatically or with -the @code{-map} option (see the Stream selection chapter). +Each input or output file 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 @code{-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 @code{0}, the second is @code{1} etc. Similarly, streams +the first input file is @code{0}, the second is @code{1}, etc. Similarly, streams within a file are referred to by their indices. E.g. @code{2:3} refers to the -fourth stream in the third input file. See also the Stream specifiers chapter. +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 @@ -50,7 +50,7 @@ options apply ONLY to the next input or output file and are reset between files. @itemize @item -To set the video bitrate of the output file to 64kbit/s: +To set the video bitrate of the output file to 64 kbit/s: @example ffmpeg -i input.avi -b:v 64k -bufsize 64k output.avi @end example @@ -96,14 +96,14 @@ 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 +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. @section Filtering Before encoding, @command{ffmpeg} can process raw audio and video frames using filters from the libavfilter library. Several chained filters form a filter -graph. @command{ffmpeg} distinguishes between two types of filtergraphs - +graph. @command{ffmpeg} distinguishes between two types of filtergraphs: simple and complex. @subsection Simple filtergraphs @@ -139,7 +139,7 @@ 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 +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: @@ -164,7 +164,7 @@ input. They can be represented with the following diagram: @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 +Note that this option is global, since a complex filtergraph, by its nature, cannot be unambiguously associated with a single stream or file. The @option{-lavfi} option is equivalent to @option{-filter_complex}. @@ -178,7 +178,7 @@ Stream copy is a mode selected by supplying the @code{copy} parameter to the @option{-codec} option. It makes @command{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: +diagram above will, in this case, simplify to this: @example _______ ______________ ________ @@ -190,7 +190,7 @@ diagram above will in this case simplify to this: @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 +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 @@ -198,14 +198,14 @@ filters is obviously also impossible, since filters work on uncompressed data. @chapter Stream selection @c man begin STREAM SELECTION -By default ffmpeg includes only one stream of each type (video, audio, subtitle) +By default, @command{ffmpeg} includes only one stream of each type (video, audio, subtitle) present in the input files and adds them to each output file. It picks the -"best" of each based upon the following criteria; for video it is the stream -with the highest resolution, for audio the stream with the most channels, for -subtitle it's the first subtitle stream. In the case where several streams of -the same type rate equally, the lowest numbered stream is chosen. +"best" of each 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. In the case where several streams of +the same type rate equally, the stream with the lowest index is chosen. -You can disable some of those defaults by using @code{-vn/-an/-sn} options. For +You can disable some of those defaults by using the @code{-vn/-an/-sn} options. For full manual control, use the @code{-map} option, which disables the defaults just described. @@ -214,7 +214,7 @@ described. @chapter Options @c man begin OPTIONS -@include avtools-common-opts.texi +@include fftools-common-opts.texi @section Main options @@ -222,7 +222,7 @@ described. @item -f @var{fmt} (@emph{input/output}) Force input or output file format. The format is normally auto detected for input -files and guessed from file extension for output files, so this option is not +files and guessed from the file extension for output files, so this option is not needed in most cases. @item -i @var{filename} (@emph{input}) @@ -232,7 +232,8 @@ input file name Overwrite output files without asking. @item -n (@emph{global}) -Do not overwrite output files but exit if file exists. +Do not overwrite output files, and exit immediately if a specified +output file already exists. @item -c[:@var{stream_specifier}] @var{codec} (@emph{input/output,per-stream}) @itemx -codec[:@var{stream_specifier}] @var{codec} (@emph{input/output,per-stream}) @@ -271,9 +272,15 @@ Set the file size limit, expressed in bytes. @item -ss @var{position} (@emph{input/output}) When used as an input option (before @code{-i}), seeks in this input file to -@var{position}. When used as an output option (before an output filename), -decodes but discards input until the timestamps reach @var{position}. This is -slower, but more accurate. +@var{position}. Note the in most formats it is not possible to seek exactly, so +@command{ffmpeg} will seek to the closest seek point before @var{position}. +When transcoding and @option{-accurate_seek} is enabled (the default), this +extra segment between the seek point and @var{position} will be decoded and +discarded. When doing stream copy or when @option{-noaccurate_seek} is used, it +will be preserved. + +When used as an output option (before an output filename), decodes but discards +input until the timestamps reach @var{position}. @var{position} may be either in seconds or in @code{hh:mm:ss[.xxx]} form. @@ -341,23 +348,33 @@ Stop writing to the stream after @var{framecount} frames. @item -q[:@var{stream_specifier}] @var{q} (@emph{output,per-stream}) @itemx -qscale[:@var{stream_specifier}] @var{q} (@emph{output,per-stream}) -Use fixed quality scale (VBR). The meaning of @var{q} is +Use fixed quality scale (VBR). The meaning of @var{q}/@var{qscale} is codec-dependent. +If @var{qscale} is used without a @var{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. @anchor{filter_option} -@item -filter[:@var{stream_specifier}] @var{filter_graph} (@emph{output,per-stream}) -Create the filter graph specified by @var{filter_graph} and use it to +@item -filter[:@var{stream_specifier}] @var{filtergraph} (@emph{output,per-stream}) +Create the filtergraph specified by @var{filtergraph} and use it to filter the stream. -@var{filter_graph} is a description of the filter graph to apply to +@var{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 filter graph, the input is associated +same type of the stream. In the filtergraph, the input is associated to the label @code{in}, and the output to the label @code{out}. See the ffmpeg-filters manual for more information about the filtergraph syntax. See the @ref{filter_complex_option,,-filter_complex option} if you -want to create filter graphs with multiple inputs and/or outputs. +want to create filtergraphs with multiple inputs and/or outputs. + +@item -filter_script[:@var{stream_specifier}] @var{filename} (@emph{output,per-stream}) +This option is similar to @option{-filter}, the only difference is that its +argument is the name of the file from which a filtergraph description is to be +read. @item -pre[:@var{stream_specifier}] @var{preset_name} (@emph{output,per-stream}) Specify the preset for matching stream(s). @@ -462,6 +479,10 @@ form @var{num}:@var{den}, where @var{num} and @var{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 @option{-vcodec copy}, it will affect the aspect ratio +stored at container level, but not the aspect ratio stored in encoded +frames, if it exists. + @item -vn (@emph{output}) Disable video recording. @@ -490,8 +511,8 @@ stream @item -vlang @var{code} Set the ISO 639 language code (3 letters) of the current video stream. -@item -vf @var{filter_graph} (@emph{output}) -Create the filter graph specified by @var{filter_graph} and use it to +@item -vf @var{filtergraph} (@emph{output}) +Create the filtergraph specified by @var{filtergraph} and use it to filter the stream. This is an alias for @code{-filter:v}, see the @ref{filter_option,,-filter option}. @@ -507,7 +528,7 @@ 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 @var{pix_fmt} is prefixed by a @code{+}, ffmpeg will exit with an error if the requested pixel format can not be selected, and automatic conversions -inside filter graphs are disabled. +inside filtergraphs are disabled. If @var{pix_fmt} is a single @code{+}, ffmpeg selects the same pixel format as the input (or graph output) and automatic conversions are disabled. @@ -522,10 +543,6 @@ 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. -@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 -ilme Force interlacing support in encoder (MPEG-2 and MPEG-4 only). Use this option if your input file is interlaced and you want @@ -604,6 +621,42 @@ would be more efficient. @item -copyinkf[:@var{stream_specifier}] (@emph{output,per-stream}) When doing stream copy, copy also non-key frames found at the beginning. + +@item -hwaccel[:@var{stream_specifier}] @var{hwaccel} (@emph{input,per-stream}) +Use hardware acceleration to decode the matching stream(s). The allowed values +of @var{hwaccel} are: +@table @option +@item none +Do not use any hardware acceleration (the default). + +@item auto +Automatically select the hardware acceleration method. + +@item vdpau +Use VDPAU (Video Decode and Presentation API for Unix) hardware acceleration. +@end table + +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, @command{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. + +@item -hwaccel_device[:@var{stream_specifier}] @var{hwaccel_device} (@emph{input,per-stream}) +Select a device to use for hardware acceleration. + +This option only makes sense when the @option{-hwaccel} option is also +specified. Its exact meaning depends on the specific hardware acceleration +method chosen. + +@table @option +@item vdpau +For VDPAU, this option specifies the X11 display/screen to use. If this option +is not specified, the value of the @var{DISPLAY} environment variable is used +@end table @end table @section Audio Options @@ -631,8 +684,8 @@ Set the audio codec. This is an alias for @code{-codec:a}. Set the audio sample format. Use @code{-sample_fmts} to get a list of supported sample formats. -@item -af @var{filter_graph} (@emph{output}) -Create the filter graph specified by @var{filter_graph} and use it to +@item -af @var{filtergraph} (@emph{output}) +Create the filtergraph specified by @var{filtergraph} and use it to filter the stream. This is an alias for @code{-filter:a}, see the @ref{filter_option,,-filter option}. @@ -865,13 +918,12 @@ Dump each input packet to stderr. When dumping packets, also dump the payload. @item -re (@emph{input}) Read input at native frame rate. Mainly used to simulate a grab device. +or live input stream (e.g. when reading from a file). Should not be used +with actual grab devices or live input streams (where it can cause packet +loss). By default @command{ffmpeg} attempts to read the input(s) as fast as possible. This option will slow down the reading of the input(s) to the native frame rate -of the input(s). It is useful for real-time output (e.g. live streaming). If -your input(s) is coming from some other live streaming source (through HTTP or -UDP for example) the server might already be in real-time, thus the option will -likely not be required. On the other hand, this is meaningful if your input(s) -is a file you are trying to push in real-time. +of the input(s). It is useful for real-time output (e.g. live streaming). @item -loop_input Loop over the input stream. Currently it works only for image streams. This option is used for automatic FFserver testing. @@ -890,7 +942,7 @@ Newly added values will have to be specified as strings always. Each frame is passed with its timestamp from the demuxer to the muxer. @item 1, cfr Frames will be duplicated and dropped to achieve exactly the requested -constant framerate. +constant frame rate. @item 2, vfr Frames are passed through with their timestamp or dropped so as to prevent 2 frames from having the same timestamp. @@ -999,10 +1051,10 @@ ffmpeg -i input.mpg -timecode 01:02:03.04 -r 30000/1001 -s ntsc output.mpg @anchor{filter_complex_option} @item -filter_complex @var{filtergraph} (@emph{global}) -Define a complex filter graph, i.e. one with arbitrary number of inputs and/or +Define a complex filtergraph, 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 the ``Filtergraph syntax'' section of the +the filtergraph, as described in the ``Filtergraph syntax'' section of the ffmpeg-filters manual. Input link labels must refer to input streams using the @@ -1046,9 +1098,30 @@ ffmpeg -filter_complex 'color=c=red' -t 5 out.mkv @end example @item -lavfi @var{filtergraph} (@emph{global}) -Define a complex filter graph, i.e. one with arbitrary number of inputs and/or +Define a complex filtergraph, i.e. one with arbitrary number of inputs and/or outputs. Equivalent to @option{-filter_complex}. +@item -filter_complex_script @var{filename} (@emph{global}) +This option is similar to @option{-filter_complex}, the only difference is that +its argument is the name of the file from which a complex filtergraph +description is to be read. + +@item -accurate_seek (@emph{input}) +This option enables or disables accurate seeking in input files with the +@option{-ss} option. It is enabled by default, so seeking is accurate when +transcoding. Use @option{-noaccurate_seek} to disable it, which may be useful +e.g. when copying some streams and transcoding the others. + +@item -override_ffserver (@emph{global}) +Overrides the input specifications from @command{ffserver}. Using this +option you can map any input stream to @command{ffserver} and control +many aspects of the encoding from @command{ffmpeg}. Without this +option @command{ffmpeg} will transmit to @command{ffserver} what is +requested by @command{ffserver}. + +The option is intended for cases where features are needed that cannot be +specified to @command{ffserver} but can be to @command{ffmpeg}. + @end table As a special exception, you can use a bitmap subtitle stream as input: it @@ -1106,7 +1179,7 @@ then it will search for the file @file{libvpx-1080p.ffpreset}. @itemize @item -For streaming at very low bitrate application, use a low frame rate +For streaming at very low bitrates, use a low frame rate and a small GOP size. This is especially true for RealVideo where the Linux player does not seem to be very fast, so it can miss frames. An example is: @@ -1185,14 +1258,14 @@ standard mixer. Grab the X11 display with ffmpeg via @example -ffmpeg -f x11grab -s cif -r 25 -i :0.0 /tmp/out.mpg +ffmpeg -f x11grab -video_size cif -framerate 25 -i :0.0 /tmp/out.mpg @end example 0.0 is display.screen number of your X11 server, same as the DISPLAY environment variable. @example -ffmpeg -f x11grab -s cif -r 25 -i :0.0+10,20 /tmp/out.mpg +ffmpeg -f x11grab -video_size cif -framerate 25 -i :0.0+10,20 /tmp/out.mpg @end example 0.0 is display.screen number of your X11 server, same as the DISPLAY environment @@ -1351,9 +1424,42 @@ ffmpeg -i src.ext -lmax 21*QP2LAMBDA dst.ext @end itemize @c man end EXAMPLES +@include config.texi +@ifset config-all +@ifset config-avutil +@include utils.texi +@end ifset +@ifset config-avcodec +@include codecs.texi +@include bitstream_filters.texi +@end ifset +@ifset config-avformat +@include formats.texi +@include protocols.texi +@end ifset +@ifset config-avdevice +@include devices.texi +@end ifset +@ifset config-swresample +@include resampler.texi +@end ifset +@ifset config-swscale +@include scaler.texi +@end ifset +@ifset config-avfilter +@include filters.texi +@end ifset +@end ifset + @chapter See Also @ifhtml +@ifset config-all +@url{ffmpeg.html,ffmpeg} +@end ifset +@ifset config-not-all +@url{ffmpeg-all.html,ffmpeg-all}, +@end ifset @url{ffplay.html,ffplay}, @url{ffprobe.html,ffprobe}, @url{ffserver.html,ffserver}, @url{ffmpeg-utils.html,ffmpeg-utils}, @url{ffmpeg-scaler.html,ffmpeg-scaler}, @@ -1367,6 +1473,12 @@ ffmpeg -i src.ext -lmax 21*QP2LAMBDA dst.ext @end ifhtml @ifnothtml +@ifset config-all +ffmpeg(1), +@end ifset +@ifset config-not-all +ffmpeg-all(1), +@end ifset ffplay(1), ffprobe(1), ffserver(1), ffmpeg-utils(1), ffmpeg-scaler(1), ffmpeg-resampler(1), ffmpeg-codecs(1), ffmpeg-bitstream-filters(1), ffmpeg-formats(1), |