From b00a4e3bfc1786276c956ce55fabbdc9a34732c1 Mon Sep 17 00:00:00 2001 From: Anton Khirnov Date: Sat, 10 Dec 2022 09:25:50 +0100 Subject: doc/ffmpeg: improve -r documentation Explain different behavior for encoding and streamcopy. --- doc/ffmpeg.texi | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) diff --git a/doc/ffmpeg.texi b/doc/ffmpeg.texi index 65634b82cf..67b3294256 100644 --- a/doc/ffmpeg.texi +++ b/doc/ffmpeg.texi @@ -877,9 +877,20 @@ This is not the same as the @option{-framerate} option used for some input forma like image2 or v4l2 (it used to be the same in older versions of FFmpeg). If in doubt use @option{-framerate} instead of the input option @option{-r}. -As an output option, duplicate or drop input frames to achieve constant output +As an output option: +@table @option +@item video encoding +Duplicate or drop frames right before encoding them to achieve constant output frame rate @var{fps}. +@item video streamcopy +Indicate to the muxer that @var{fps} is the stream frame rate. No data is +dropped or duplicated in this case. This may produce invalid files if @var{fps} +does not match the actual stream frame rate as determined by packet timestamps. +See also the @code{setts} bitstream filter. + +@end table + @item -fpsmax[:@var{stream_specifier}] @var{fps} (@emph{output,per-stream}) Set maximum frame rate (Hz value, fraction or abbreviation). -- cgit v1.2.3