文件操作 - avifdec.1.md

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% AVIFDEC(1) | General Commands Manual
%
% 2022-04-30

# NAME

avifdec - decompress an AVIF file to an image file

# SYNOPSIS

**avifdec** [_options_] _input.avif_ _output._[_jpg_|_jpeg_|_png_|_y4m_]

**avifdec** **\--info** _input.avif_

# DESCRIPTION

**avifdec** decompresses an AVIF file to an image file.
Output format can be either JPEG, PNG or YUV4MPEG2 (Y4M).

# OPTIONS

**-h**, **\--help**
:   Show syntax help.

**-V**, **\--version**
:   Show the version number.

**-j**, **\--jobs** _J_
:   Number of jobs (worker threads).
    1 or less means single-threaded.
    Default is 1.
    Use **all** to use all available cores.

**-c**, **\--codec** _C_
:   AV1 codec to use.
    Possible values depend on the codecs enabled at build time (see **\--help**
    or **\--version** for the available codecs).
    Default is auto-selected from the available codecs.

Possible values are:

:   - **aom**
        - **dav1d**
        - **libgav1**

**-d**, **\--depth** _D_
:   Output PNG depth.
    Ignored when the output format is JPEG (always 8 bits per channel) or Y4M
    (input depth is retained).

Possible values are:

:   - **8**
        - **16**

**-q**, **\--quality** _Q_
:   Output JPEG quality in the range **0**-**100**.
    Default is 90.
    Ignored if the output format is not JPEG.

**\--png-compress** _L_
:   Output PNG compression level in the range **0**-**9** (fastest to maximum
    compression).
    Default is libpng's built-in default.
    Ignored if the output format is not PNG.

**-u**, **\--upsampling** _U_
:   Chroma upsampling method.
    Ignored unless the input format is 4:2:0 or 4:2:2.

Possible values are:

:   - **automatic** (default)
        - **fastest**
        - **best**
        - **nearest**
        - **bilinear**

**-r**, **\--raw-color**
:   Output raw RGB values instead of multiplying by alpha when saving to opaque
    formats.
    This is available if the output format is JPEG, and not applicable to y4m.

**\--index** _I_
:   When decoding an image sequence or progressive image, specify which frame
    index to decode.
    Default is 0.

**\--progressive**
:   Enable progressive AVIF processing.
    If a progressive image is encountered and **\--progressive** is passed,
    **avifdec** will use **\--index** to choose which layer to decode (in
    progressive order).

**\--no-strict**
:   Disable strict decoding, which disables strict validation checks and errors.

**-i**, **\--info**
:   Decode all frames and display all image information instead of saving to
    disk.

**\--ignore-icc**
:   If the input file contains an embedded ICC profile, ignore it (no-op if
    absent).

**\--size-limit** _C_
:   Specifies the image size limit (in total pixels) that should be tolerated.
    Default is 268,435,456 pixels (16,384 by 16,384 pixels for a square image).

**\--dimension-limit** _C_
:   Specifies the image dimension limit (width or height) that should be
    tolerated.
    Default is 32,768. Set it to 0 to ignore the limit.

**\--**
:   Signals the end of options. Everything after this is interpreted as file names.

# EXAMPLES

Decompress an AVIF file to a PNG file:
:   $ **avifdec input.avif output.png**

# REPORTING BUGS

Bugs can be reported on GitHub at:
:   <https://github.com/AOMediaCodec/libavif/issues>

# SEE ALSO

**avifenc**(1)

文件操作 - avifdec.1.md

文件: /usr/local/src/libavif-0.11.1/doc/avifdec.1.md

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