GstVideoScaler: GStreamer Base Plugins 1.0 Library Reference Manual

## GstVideoScaler GstVideoScaler — Utility object for rescaling video frames |

## Functions

void | gst_video_scaler_2d ()
GstVideoScaler * | gst_video_scaler_combine_packed_YUV ()
void | gst_video_scaler_free ()
const gdouble * | gst_video_scaler_get_coeff ()
void | gst_video_scaler_horizontal ()
GstVideoScaler * | gst_video_scaler_new ()
void | gst_video_scaler_vertical ()
guint | gst_video_scaler_get_max_taps ()

## Types and Values

| GstVideoScaler
enum | GstVideoScalerFlags
#define | GST_VIDEO_SCALER_OPT_DITHER_METHOD

## Includes

    #include <gst/video/video.h>

## Description

GstVideoScaler is a utility object for rescaling and resampling video frames using various interpolation / sampling methods.

## Functions

### gst_video_scaler_2d ()

    void
    gst_video_scaler_2d (GstVideoScaler *hscale,
                         GstVideoScaler *vscale,
                         GstVideoFormat format,
                         gpointer src,
                         gint src_stride,
                         gpointer dest,
                         gint dest_stride,
                         guint x,
                         guint y,
                         guint width,
                         guint height);

Scale a rectangle of pixels in `src` with `src_stride` to `dest` with `dest_stride` using the horizontal scaler `hscaler` and the vertical scaler `vscale` .

One or both of `hscale` and `vscale` can be NULL to only perform scaling in one dimension or do a copy without scaling.

`x` and `y` are the coordinates in the destination image to process.

#### Parameters

hscale | a horzontal GstVideoScaler |
vscale | a vertical GstVideoScaler |
format | a GstVideoFormat for `srcs` and `dest` |
src | source pixels |
src_stride | source pixels stride |
dest | destination pixels |
dest_stride | destination pixels stride |
x | the horizontal destination offset |
y | the vertical destination offset |
width | the number of output pixels to scale |
height | the number of output lines to scale |

### gst_video_scaler_combine_packed_YUV ()

    GstVideoScaler *
    gst_video_scaler_combine_packed_YUV (GstVideoScaler *y_scale,
                                         GstVideoScaler *uv_scale,
                                         GstVideoFormat in_format,
                                         GstVideoFormat out_format);

Combine a scaler for Y and UV into one scaler for the packed `format` .

[skip]

#### Parameters

y_scale | a scaler for the Y component |
uv_scale | a scaler for the U and V components |
in_format | the input video format |
out_format | the output video format |

#### Returns

a new horizontal videoscaler for `format` .

Since: 1.6

### gst_video_scaler_free ()

    void
    gst_video_scaler_free (GstVideoScaler *scale);

Free a previously allocated GstVideoScaler `scale` .

#### Parameters

scale | a GstVideoScaler |

### gst_video_scaler_get_coeff ()

    const gdouble *
    gst_video_scaler_get_coeff (GstVideoScaler *scale,
                                guint out_offset,
                                guint *in_offset,
                                guint *n_taps);

For a given pixel at `out_offset` , get the first required input pixel at `in_offset` and the `n_taps` filter coefficients.

Note that for interlaced content, `in_offset` needs to be incremented with 2 to get the next input line.

#### Parameters

scale | a GstVideoScaler |
out_offset | an output offset |
in_offset | result input offset |
n_taps | result n_taps |

#### Returns

an array of `n_tap` gdouble values with filter coefficients.

### gst_video_scaler_horizontal ()

    void
    gst_video_scaler_horizontal (GstVideoScaler *scale,
                                 GstVideoFormat format,
                                 gpointer src,
                                 gpointer dest,
                                 guint dest_offset,
                                 guint width);

Horizontally scale the pixels in `src` to `dest` , starting from `dest_offset` for `width` samples.

#### Parameters

scale | a GstVideoScaler |
format | a GstVideoFormat for `src` and `dest` |
src | source pixels |
dest | destination pixels |
dest_offset | the horizontal destination offset |
width | the number of pixels to scale |

### gst_video_scaler_new ()

    GstVideoScaler *
    gst_video_scaler_new (GstVideoResamplerMethod method,
                          GstVideoScalerFlags flags,
                          guint n_taps,
                          guint in_size,
                          guint out_size,
                          GstStructure *options);

Make a new `method` video scaler. `in_size` source lines/pixels will be scaled to `out_size` destination lines/pixels.

`n_taps` specifies the amount of pixels to use from the source for one output pixel. If n_taps is 0, this function chooses a good value automatically based on the `method` and `in_size` /`out_size` .

[skip]

#### Parameters

method | a GstVideoResamplerMethod |
flags | GstVideoScalerFlags |
n_taps | number of taps to use |
in_size | number of source elements |
out_size | number of destination elements |
options | extra options. | [allow-none]

#### Returns

a GstVideoScaler

### gst_video_scaler_vertical ()

    void
    gst_video_scaler_vertical (GstVideoScaler *scale,
                               GstVideoFormat format,
                               gpointer src_lines[],
                               gpointer dest,
                               guint dest_offset,
                               guint width);

Vertically combine `width` pixels in the lines in `src_lines` to `dest` . `dest` is the location of the target line at `dest_offset` and `srcs` are the input lines for `dest_offset` , as obtained with `gst_video_scaler_get_info()`.

#### Parameters

scale | a GstVideoScaler |
format | a GstVideoFormat for `srcs` and `dest` |
src_lines | source pixels lines |
dest | destination pixels |
dest_offset | the vertical destination offset |
width | the number of pixels to scale |

### gst_video_scaler_get_max_taps ()

    guint
    gst_video_scaler_get_max_taps (GstVideoScaler *scale);

Get the maximum number of taps for `scale` .

#### Parameters

scale | a GstVideoScaler |

#### Returns

the maximum number of taps

## Types and Values

### GstVideoScaler

    typedef struct _GstVideoScaler GstVideoScaler;

### enum GstVideoScalerFlags

Different scale flags.

#### Members

GST_VIDEO_SCALER_FLAG_NONE | no flags |
GST_VIDEO_SCALER_FLAG_INTERLACED | Set up a scaler for interlaced content |

### GST_VIDEO_SCALER_OPT_DITHER_METHOD

    #define GST_VIDEO_SCALER_OPT_DITHER_METHOD   "GstVideoScaler.dither-method"

GST_TYPE_VIDEO_DITHER_METHOD, The dither method to use for propagating quatization errors.