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Diffstat (limited to 'doc/ffmpeg.texi')
| -rw-r--r-- | doc/ffmpeg.texi | 58 |
1 files changed, 53 insertions, 5 deletions
diff --git a/doc/ffmpeg.texi b/doc/ffmpeg.texi index 801c083705..9bd548ce4e 100644 --- a/doc/ffmpeg.texi +++ b/doc/ffmpeg.texi @@ -2145,14 +2145,62 @@ type -- see the @option{-filter} options. @var{filtergraph} is a description of the filtergraph, as described in the ``Filtergraph syntax'' section of the ffmpeg-filters manual. -Input link labels must refer to either input streams or loopback decoders. For -input streams, use 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. +Inputs to a complex filtergraph may come from different source types, +distinguished by the format of the corresponding link label: +@itemize +@item +To connect an input stream, use @code{[file_index:stream_specifier]} (i.e. the +same syntax as @option{-map}). If @var{stream_specifier} matches multiple +streams, the first one will be used. -For decoders, the link label must be [dec:@var{dec_idx}], where @var{dec_idx} is +@item +To connect a loopback decoder use [dec:@var{dec_idx}], where @var{dec_idx} is the index of the loopback decoder to be connected to given input. +@item +To connect an output from another complex filtergraph, use its link label. E.g +the following example: + +@example +ffmpeg -i input.mkv \ + -filter_complex '[0:v]scale=size=hd1080,split=outputs=2[for_enc][orig_scaled]' \ + -c:v libx264 -map '[for_enc]' output.mkv \ + -dec 0:0 \ + -filter_complex '[dec:0][orig_scaled]hstack[stacked]' \ + -map '[stacked]' -c:v ffv1 comparison.mkv +@end example + +reads an input video and +@itemize +@item +(line 2) uses a complex filtergraph with one input and two outputs +to scale the video to 1920x1080 and duplicate the result to both +outputs; + +@item +(line 3) encodes one scaled output with @code{libx264} and writes the result to +@file{output.mkv}; + +@item +(line 4) decodes this encoded stream with a loopback decoder; + +@item +(line 5) places the output of the loopback decoder (i.e. the +@code{libx264}-encoded video) side by side with the scaled original input; + +@item +(line 6) combined video is then losslessly encoded and written into +@file{comparison.mkv}. + +@end itemize + +Note that the two filtergraphs cannot be combined into one, because then there +would be a cycle in the transcoding pipeline (filtergraph output goes to +encoding, from there to decoding, then back to the same graph), and such cycles +are not allowed. + +@end itemize + An unlabeled input will be connected to the first unused input stream of the matching type. |