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f0d6a14b64
We use the 'do not blend' option for creating independent frames. We also mark the already independent frames as 'do not blend'. This bounds the maximum number of frames that need to be decoded to decode a given frame, thus leading to a much better decoding performance. Change-Id: I7cef98af2b53751ec36993fd2bd54f7f4c4aad2b
110 lines
3.6 KiB
Groff
110 lines
3.6 KiB
Groff
.\" Hey, EMACS: -*- nroff -*-
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.TH GIF2WEBP 1 "February 01, 2013"
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.SH NAME
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gif2webp \- Convert a GIF image to WebP
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.SH SYNOPSIS
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.B gif2webp
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.RI [ options ] " input_file.gif \-o output_file.webp
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.br
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.SH DESCRIPTION
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This manual page documents the
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.B gif2webp
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command.
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.PP
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\fBgif2webp\fP converts a GIF image to a WebP image.
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.SH OPTIONS
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The basic options are:
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.TP
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.BI \-o " string
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Specify the name of the output WebP file. If omitted, \fBgif2webp\fP will
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perform conversion but only report statistics.
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.TP
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.B \-h, \-help
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Usage information.
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.TP
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.B \-version
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Print the version number (as major.minor.revision) and exit.
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.TP
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.B \-lossy
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Encode the image using lossy compression.
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.TP
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.BI \-q " float
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Specify the compression factor for RGB channels between 0 and 100. The default
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is 75.
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.br
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In case of lossless compression (default), a small factor enables faster
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compression speed, but produces a larger file. Maximum compression is achieved
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by using a value of 100.
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.br
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In case of lossy compression (specified by the \-lossy option), a small factor
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produces a smaller file with lower quality. Best quality is achieved by using a
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value of 100.
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.TP
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.BI \-m " int
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Specify the compression method to use. This parameter controls the
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trade off between encoding speed and the compressed file size and quality.
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Possible values range from 0 to 6. Default value is 4.
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When higher values are used, the encoder will spend more time inspecting
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additional encoding possibilities and decide on the quality gain.
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Lower value can result is faster processing time at the expense of
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larger file size and lower compression quality.
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.TP
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.BI \-kmax " int
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Relevant only for animated images with large number of frames (>50).
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Specify the maximum distance between consecutive key frames (independently
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decodable frames) in the output image. The tool will insert some key frames into
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the output image as needed so that this criteria is satisfied. A value of 0 will
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turn off insertion of key frames.
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Typical values are in the range 5 to 30. Default value is 9.
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When lower values are used, more frames will be converted to key frames. This
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may lead to smaller number of frames required to decode a frame on average,
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thereby improving the decoding performance. But this may lead to slightly bigger
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file sizes.
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Higher values may lead to worse decoding performance, but smaller file sizes.
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.TP
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.BI \-f " int
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For lossy encoding only (specified by the \-lossy option). Specify the strength
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of the deblocking filter, between 0 (no filtering) and 100 (maximum filtering).
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A value of 0 will turn off any filtering. Higher value will increase the
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strength of the filtering process applied after decoding the picture. The higher
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the value the smoother the picture will appear. Typical values are usually in
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the range of 20 to 50.
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.TP
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.B \-v
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Print extra information.
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.TP
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.B \-quiet
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Do not print anything.
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.SH BUGS
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Please report all bugs to our issue tracker:
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http://code.google.com/p/webp/issues
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.br
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Patches welcome! See this page to get started:
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http://www.webmproject.org/code/contribute/submitting-patches/
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.SH EXAMPLES
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gif2webp picture.gif \-o picture.webp
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.br
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gif2webp \-q 70 picture.gif \-o picture.webp
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.br
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gif2webp \-lossy \-m 3 picture.gif \-o picture_lossy.webp
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.br
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gif2webp \-lossy \-f 50 picture.gif \-o picture.webp
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.SH AUTHORS
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\fBgif2webp\fP was written by the WebP team.
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.br
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The latest source tree is available at http://www.webmproject.org/code
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.PP
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This manual page was written by Urvang Joshi <urvang@google.com>, for the
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Debian project (and may be used by others).
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.SH SEE ALSO
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.BR dwebp (1),
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.BR cwebp (1),
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.BR webpmux (1).
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.br
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Please refer to http://developers.google.com/speed/webp/ for additional
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information.
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