NAME
yuvfps - Converts to a different frame rate
SYNOPSIS
yuvfps [-r Num:Den] [-s Num:Den] [-i Interlacing] [-I Interlacing] [-c]
[-n] [-w] [-v 0-2] [-h]
DESCRIPTION
yuvfps is a general (UP or DOWN) resampling utility that is provided to
allow the generation of video streams with the frame rates required for
each standard video format. yuvfps reads a YUV4MPEG stream from the
standard input and outputs a YUV4MPEG stream to the standard output in
which frames from the original ones are skipped (downsampling) or
duplicated (upsampling). This allows for other mjpegtools that require
a specific frame rate to process the stream.
yuvfps uses by default Bresenham’s algorithm to do the resampling so
that the new video stream is similar to the original one. Note,
however, that downscaling is a non-reversible operation because frames
are dropped. Moreover, the resulting video stream may not have the
exact same duration as the original one if the new frame rate is not a
whole multiple of the original rate.
As an alternative to simply dropping or duplicating frames each output
frame/field can be produced as a weighted average of the two temporally
closest input frames/fields. In this mode, yuvfps can also change the
interlacing mode of the stream.
yuvfps also can "fix" the framerate specified in the YUV4MPEG header.
This allows for the generation of effects (fast-forwarding, slow
motion) and also when the source stream has some framerate that is very
close, but not exactly, the rate required for some standard video (for
example, 24.9 vs 25).
OPTIONS
-r Num:Den
Specifies the resulting stream frame rate.
-s Num:Den
Ignores the frame rate in the input stream and assumes this
frame rate for the input stream.
-i Interlacing
Specifies the interlacing mode of the resulting stream. The
interlacing mode can be changed only when using the weighted
average resampling mode (the -w option).
p - progressive (non-interlaced)
t - top-field first
b - bottom-field first
-I Interlacing
Ignores the interlacing mode information in the input stream and
assumes this interlacing mode for the input stream. The
possible values are the same as for the -i option.
-c
Changes the stream header frame rate and interlacing mode in the
output stream but copies frames from the original stream without
changes. The -r and -i options specify the frame rate and
interlacing mode for the output stream header.
-n
By default yuvfps tries to find a normalized framerate. Some
programs create framerates like: 29969909:1000000 which is
actually th typical NTSC framerate of 30000:1001. yuvfps prints
out the normalizes values and the original when it starts. If
you think the normalized value is not correct and want yuvfps to
use the original given number you have to add that option. So
yuvfps does not try to normalize the values.
-w
Produce each output frame/field as a weighted average of the two
temporally closest input frames/fields instead of simply
dropping or duplicating frames. The blending of two adjacent
frames/fields reduces visible stepping compared to the default
drop/duplicate algorithm but as a drawback it makes fast moving
objects appear blurred and is much slower.
-v [0,1,2]
Set verbosity level.
0 = warnings and error messages only.
1 = add informative messages, like the framerate conversation
information.
2 = add chatty debugging message, too.
AUTHOR
This man page was written by Alfonso García-Patiño Barbolani.
Johannes Lehtinen added information about the weighted average
resampling mode and the related options.
If you have questions, remarks, problems or you just want to contact
the developers, the main mailing list for the MJPEG-tools is:
mjpeg-users@lists.sourceforge.net
For more info, see our website at
http://mjpeg.sourceforge.net/
SEE ALSO
yuvscaler(1), mjpegtools(1), lavpipe(1), lav2yuv(1) mpeg2enc(1)