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.TH "yuvfps" "1" "8 Jan 2006" "MJPEG Linux Square" "MJPEG tools manual"
.SH NAME
yuvfps \- Converts to a different frame rate
.SH SYNOPSIS
.B yuvfps
.RB [ -r
.IR Num:Den ]
.RB [ -s
.IR Num:Den ]
.RB [ -i
.IR Interlacing ]
.RB [ -I
.IR Interlacing ]
.RB [ -c ]
.RB [ -n ]
.RB [ -w ]
.RB [ -v\ 0 - 2 ]
.RB [ -h ]
.SH DESCRIPTION
\fByuvfps\fP 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. \fByuvfps\fP 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.
\fByuvfps\fP 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, \fByuvfps\fP can also change the interlacing mode of the stream.
\fByuvfps\fP 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).
.SH OPTIONS
.TP
.B -r \fBNum:Den\fP
.IP
Specifies the resulting stream frame rate.
.TP
.B -s \fBNum:Den\fP
.IP
Ignores the frame rate in the input stream and assumes this frame rate for the
input stream.
.TP
.B -i \fBInterlacing\fP
.IP
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).
.IP
p - progressive (non-interlaced)
.br
t - top-field first
.br
b - bottom-field first
.TP
.B -I \fBInterlacing\fP
.IP
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.
.TP
.B -c
.IP
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.
.TP
.B -n
.IP
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.
.TP
.B -w
.IP
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.
.TP
.B \-v " [0,1,2]"
.IP
Set verbosity level.
0 = warnings and error messages only.
1 = add informative messages, like the framerate conversation information.
2 = add chatty debugging message, too.
.SH AUTHOR
This man page was written by Alfonso García-Patiño Barbolani.
.br
Johannes Lehtinen added information about the weighted average resampling
mode and the related options.
.br
If you have questions, remarks, problems or you just want to contact
the developers, the main mailing list for the MJPEG\-tools is:
\fImjpeg\-users@lists.sourceforge.net\fP
.TP
For more info, see our website at
.I http://mjpeg.sourceforge.net/
.SH SEE ALSO
.BR yuvscaler (1),
.BR mjpegtools (1),
.BR lavpipe (1),
.BR lav2yuv (1)
.BR mpeg2enc (1)
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