X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=doc%2Ffilters.texi;h=e77256e0056f896ae25e1d86eb87109b044fcaf1;hb=6af2480aa62e96fbfa4f2f99b80280ce77dafafd;hp=0314bfaf20a7383d9505f88777d449b8ccaccee2;hpb=a2cd9be212fca02dd3d6ee65cb6ab9f84c5e28e5;p=ffmpeg diff --git a/doc/filters.texi b/doc/filters.texi index 0314bfaf20a..e77256e0056 100644 --- a/doc/filters.texi +++ b/doc/filters.texi @@ -107,10 +107,208 @@ build. Below is a description of the currently available audio filters. +@section aformat + +Convert the input audio to one of the specified formats. The framework will +negotiate the most appropriate format to minimize conversions. + +The filter accepts the following named parameters: +@table @option + +@item sample_fmts +A comma-separated list of requested sample formats. + +@item sample_rates +A comma-separated list of requested sample rates. + +@item channel_layouts +A comma-separated list of requested channel layouts. + +@end table + +If a parameter is omitted, all values are allowed. + +For example to force the output to either unsigned 8-bit or signed 16-bit stereo: +@example +aformat=sample_fmts\=u8\,s16:channel_layouts\=stereo +@end example + +@section amix + +Mixes multiple audio inputs into a single output. + +For example +@example +avconv -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex amix=inputs=3:duration=first:dropout_transition=3 OUTPUT +@end example +will mix 3 input audio streams to a single output with the same duration as the +first input and a dropout transition time of 3 seconds. + +The filter accepts the following named parameters: +@table @option + +@item inputs +Number of inputs. If unspecified, it defaults to 2. + +@item duration +How to determine the end-of-stream. +@table @option + +@item longest +Duration of longest input. (default) + +@item shortest +Duration of shortest input. + +@item first +Duration of first input. + +@end table + +@item dropout_transition +Transition time, in seconds, for volume renormalization when an input +stream ends. The default value is 2 seconds. + +@end table + @section anull Pass the audio source unchanged to the output. +@section asplit + +Split input audio into several identical outputs. + +The filter accepts a single parameter which specifies the number of outputs. If +unspecified, it defaults to 2. + +For example +@example +avconv -i INPUT -filter_complex asplit=5 OUTPUT +@end example +will create 5 copies of the input audio. + +@section asyncts +Synchronize audio data with timestamps by squeezing/stretching it and/or +dropping samples/adding silence when needed. + +The filter accepts the following named parameters: +@table @option + +@item compensate +Enable stretching/squeezing the data to make it match the timestamps. + +@item min_delta +Minimum difference between timestamps and audio data (in seconds) to trigger +adding/dropping samples. + +@item max_comp +Maximum compensation in samples per second. + +@item first_pts +Assume the first pts should be this value. +This allows for padding/trimming at the start of stream. By default, no +assumption is made about the first frame's expected pts, so no padding or +trimming is done. For example, this could be set to 0 to pad the beginning with +silence if an audio stream starts after the video stream. + +@end table + +@section channelsplit +Split each channel in input audio stream into a separate output stream. + +This filter accepts the following named parameters: +@table @option +@item channel_layout +Channel layout of the input stream. Default is "stereo". +@end table + +For example, assuming a stereo input MP3 file +@example +avconv -i in.mp3 -filter_complex channelsplit out.mkv +@end example +will create an output Matroska file with two audio streams, one containing only +the left channel and the other the right channel. + +To split a 5.1 WAV file into per-channel files +@example +avconv -i in.wav -filter_complex +'channelsplit=channel_layout=5.1[FL][FR][FC][LFE][SL][SR]' +-map '[FL]' front_left.wav -map '[FR]' front_right.wav -map '[FC]' +front_center.wav -map '[LFE]' lfe.wav -map '[SL]' side_left.wav -map '[SR]' +side_right.wav +@end example + +@section channelmap +Remap input channels to new locations. + +This filter accepts the following named parameters: +@table @option +@item channel_layout +Channel layout of the output stream. + +@item map +Map channels from input to output. The argument is a comma-separated list of +mappings, each in the @code{@var{in_channel}-@var{out_channel}} or +@var{in_channel} form. @var{in_channel} can be either the name of the input +channel (e.g. FL for front left) or its index in the input channel layout. +@var{out_channel} is the name of the output channel or its index in the output +channel layout. If @var{out_channel} is not given then it is implicitly an +index, starting with zero and increasing by one for each mapping. +@end table + +If no mapping is present, the filter will implicitly map input channels to +output channels preserving index. + +For example, assuming a 5.1+downmix input MOV file +@example +avconv -i in.mov -filter 'channelmap=map=DL-FL\,DR-FR' out.wav +@end example +will create an output WAV file tagged as stereo from the downmix channels of +the input. + +To fix a 5.1 WAV improperly encoded in AAC's native channel order +@example +avconv -i in.wav -filter 'channelmap=1\,2\,0\,5\,3\,4:channel_layout=5.1' out.wav +@end example + +@section join +Join multiple input streams into one multi-channel stream. + +The filter accepts the following named parameters: +@table @option + +@item inputs +Number of input streams. Defaults to 2. + +@item channel_layout +Desired output channel layout. Defaults to stereo. + +@item map +Map channels from inputs to output. The argument is a comma-separated list of +mappings, each in the @code{@var{input_idx}.@var{in_channel}-@var{out_channel}} +form. @var{input_idx} is the 0-based index of the input stream. @var{in_channel} +can be either the name of the input channel (e.g. FL for front left) or its +index in the specified input stream. @var{out_channel} is the name of the output +channel. +@end table + +The filter will attempt to guess the mappings when those are not specified +explicitly. It does so by first trying to find an unused matching input channel +and if that fails it picks the first unused input channel. + +E.g. to join 3 inputs (with properly set channel layouts) +@example +avconv -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex join=inputs=3 OUTPUT +@end example + +To build a 5.1 output from 6 single-channel streams: +@example +avconv -i fl -i fr -i fc -i sl -i sr -i lfe -filter_complex +'join=inputs=6:channel_layout=5.1:map=0.0-FL\,1.0-FR\,2.0-FC\,3.0-SL\,4.0-SR\,5.0-LFE' +out +@end example + @section resample Convert the audio sample format, sample rate and channel layout. This filter is not meant to be used directly, it is inserted automatically by libavfilter @@ -769,6 +967,19 @@ format=yuv420p format=yuv420p:yuv444p:yuv410p @end example +@section fps + +Convert the video to specified constant framerate by duplicating or dropping +frames as necessary. + +This filter accepts the following named parameters: +@table @option + +@item fps +Desired output framerate. + +@end table + @anchor{frei0r} @section frei0r @@ -1967,6 +2178,11 @@ to the pad with identifier "in". Read a video stream from a movie container. +Note that this source is a hack that bypasses the standard input path. It can be +useful in applications that do not support arbitrary filter graphs, but its use +is discouraged in those that do. Specifically in @command{avconv} this filter +should never be used, the @option{-filter_complex} option fully replaces it. + It accepts the syntax: @var{movie_name}[:@var{options}] where @var{movie_name} is the name of the resource to read (not necessarily a file but also a device or a stream accessed through some protocol),