yuvfps.1

Motion JPEG编解码器源代码

.TH "yuvfps" "1" "19 November 2002" "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 [ -c ]
.RB [ -n ]
.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 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.
  
\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 -c 
.IP
Changes the stream header frame rate in the output stream, but copies withouth
changing the frames from the original stream. with the -r option you tell yuvfps which framerate should be set. 
.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 -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 \-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 Garc韆-Pati駉 Barbolani.
.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\[e-mail]\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)