zscale
Scale (resize) the input video, using the z.lib library: https://github.com/sekrit-twc/zimg. To enable compilation of this filter, you need to configure FFmpeg with --enable-libzimg.
The zscale filter forces the output display aspect ratio to be the same as the input, by changing the output sample aspect ratio.
If the input image format is different from the format requested by the next filter, the zscale filter will convert the input to the requested format.
Options
The filter accepts the following options.
- 'width, w'
- 'height, h'
-
Set the output video dimension expression. Default value is the input dimension.
If the width or w value is 0, the input width is used for the output. If the height or h value is 0, the input height is used for the output.
If one and only one of the values is -n with n >= 1, the zscale filter will use a value that maintains the aspect ratio of the input image, calculated from the other specified dimension. After that it will, however, make sure that the calculated dimension is divisible by n and adjust the value if necessary.
If both values are -n with n >= 1, the behavior will be identical to both values being set to 0 as previously detailed.
See below for the list of accepted constants for use in the dimension expression.
- 'size, s'
-
Set the video size. For the syntax of this option, check the (ffmpeg-utils)"Video size" section in the ffmpeg-utils manual.
- 'dither, d'
-
Set the dither type.
Possible values are:
- none
- ordered
- random
- error_diffusion
- ordered
Default is none.
- none
- 'filter, f'
-
Set the resize filter type.
Possible values are:
- point
- bilinear
- bicubic
- spline16
- spline36
- lanczos
- bilinear
Default is bilinear.
- point
- 'range, r'
-
Set the color range.
Possible values are:
- input
- limited
- full
- limited
Default is same as input.
- input
- 'primaries, p'
-
Set the color primaries.
Possible values are:
- input
- 709
- unspecified
- 170m
- 240m
- 2020
- 709
Default is same as input.
- input
- 'transfer, t'
-
Set the transfer characteristics.
Possible values are:
- input
- 709
- unspecified
- 601
- linear
- 2020_10
- 2020_12
- smpte2084
- iec61966-2-1
- arib-std-b67
- 709
Default is same as input.
- input
- 'matrix, m'
-
Set the colorspace matrix.
Possible value are:
- input
- 709
- unspecified
- 470bg
- 170m
- 2020_ncl
- 2020_cl
- 709
Default is same as input.
- input
- 'rangein, rin'
-
Set the input color range.
Possible values are:
- input
- limited
- full
- limited
Default is same as input.
- input
- 'primariesin, pin'
-
Set the input color primaries.
Possible values are:
- input
- 709
- unspecified
- 170m
- 240m
- 2020
- 709
Default is same as input.
- input
- 'transferin, tin'
-
Set the input transfer characteristics.
Possible values are:
- input
- 709
- unspecified
- 601
- linear
- 2020_10
- 2020_12
- 709
Default is same as input.
- input
- 'matrixin, min'
-
Set the input colorspace matrix.
Possible value are:
- input
- 709
- unspecified
- 470bg
- 170m
- 2020_ncl
- 2020_cl
- 709
- input
- 'chromal, c'
-
Set the output chroma location.
Possible values are:
- input
- left
- center
- topleft
- top
- bottomleft
- bottom
- left
- input
- 'chromalin, cin'
-
Set the input chroma location.
Possible values are:
- input
- left
- center
- topleft
- top
- bottomleft
- bottom
- left
- input
- 'npl'
-
Set the nominal peak luminance.
The values of the 'w' and 'h' options are expressions containing the following constants:
- in_w
- in_h
-
The input width and height
- iw
- ih
-
These are the same as in_w and in_h.
- out_w
- out_h
-
The output (scaled) width and height
- ow
- oh
-
These are the same as out_w and out_h
- a
-
The same as iw / ih
- sar
-
input sample aspect ratio
- dar
-
The input display aspect ratio. Calculated from
(iw / ih) * sar. - hsub
- vsub
-
horizontal and vertical input chroma subsample values. For example for the pixel format "yuv422p" hsub is 2 and vsub is 1.
- ohsub
- ovsub
-
horizontal and vertical output chroma subsample values. For example for the pixel format "yuv422p" hsub is 2 and vsub is 1.
OpenCL Video Filters
Below is a description of the currently available OpenCL video filters.
To enable compilation of these filters you need to configure FFmpeg with --enable-opencl.
Running OpenCL filters requires you to initialize a hardware device and to pass that device to all filters in any filter graph.
- '-init_hw_device opencl[=name][:device[,key=value...]]'
-
Initialise a new hardware device of type opencl called name, using the given device parameters.
- '-filter_hw_device name'
-
Pass the hardware device called name to all filters in any filter graph.
For more detailed information see https://www.ffmpeg.org/ffmpeg.html#Advanced-Video-options
- Example of choosing the first device on the second platform and running avgblur_opencl filter with default parameters on it.
-init_hw_device opencl=gpu:1.0 -filter_hw_device gpu -i INPUT -vf "hwupload, avgblur_opencl, hwdownload" OUTPUT
Since OpenCL filters are not able to access frame data in normal memory, all frame data needs to be uploaded(hwupload) to hardware surfaces connected to the appropriate device before being used and then downloaded(hwdownload) back to normal memory. Note that hwupload will upload to a surface with the same layout as the software frame, so it may be necessary to add a format filter immediately before to get the input into the right format and hwdownload does not support all formats on the output - it may be necessary to insert an additional format filter immediately following in the graph to get the output in a supported format.