GstVideoResampler

GstVideoResampler — Utility structure for resampler information

Synopsis

#include <gst/video/video-resampler.h>

struct              GstVideoResampler;
enum                GstVideoResamplerFlags;
enum                GstVideoResamplerMethod;
void                gst_video_resampler_clear           (GstVideoResampler *resampler);
gboolean            gst_video_resampler_init            (GstVideoResampler *resampler,
                                                         GstVideoResamplerMethod method,
                                                         GstVideoResamplerFlags flags,
                                                         guint n_phases,
                                                         guint n_taps,
                                                         gdouble shift,
                                                         guint in_size,
                                                         guint out_size,
                                                         GstStructure *options);
#define             GST_VIDEO_RESAMPLER_OPT_CUBIC_B
#define             GST_VIDEO_RESAMPLER_OPT_CUBIC_C
#define             GST_VIDEO_RESAMPLER_OPT_ENVELOPE
#define             GST_VIDEO_RESAMPLER_OPT_MAX_TAPS
#define             GST_VIDEO_RESAMPLER_OPT_SHARPEN
#define             GST_VIDEO_RESAMPLER_OPT_SHARPNESS

Description

GstVideoResampler is a structure which holds the information required to perform various kinds of resampling filtering.

Details

struct GstVideoResampler

struct GstVideoResampler {
  gint in_size;
  gint out_size;
  guint max_taps;
  guint n_phases;
  guint32 *offset;
  guint32 *phase;
  guint32 *n_taps;
  gdouble *taps;
};

A structure holding resampler information.

gint `in_size`;	the input size
gint `out_size`;	the output size
guint `max_taps`;	the maximum number of taps
guint `n_phases`;	the number of phases
guint32 *`offset`;	array with the source offset for each output element
guint32 *`phase`;	array with the phase to use for each output element
guint32 *`n_taps`;	array with new number of taps for each phase
gdouble *`taps`;	the taps for all phases

Since 1.6

enum GstVideoResamplerFlags

typedef enum {
  GST_VIDEO_RESAMPLER_FLAG_NONE                 = (0),
  GST_VIDEO_RESAMPLER_FLAG_HALF_TAPS            = (1 << 0),
} GstVideoResamplerFlags;

Different resampler flags.

`GST_VIDEO_RESAMPLER_FLAG_NONE`	no flags
`GST_VIDEO_RESAMPLER_FLAG_HALF_TAPS`	when no taps are given, half the number of calculated taps. This can be used when making scalers for the different fields of an interlaced picture. Since 1.10

Since 1.6

enum GstVideoResamplerMethod

typedef enum {
  GST_VIDEO_RESAMPLER_METHOD_NEAREST,
  GST_VIDEO_RESAMPLER_METHOD_LINEAR,
  GST_VIDEO_RESAMPLER_METHOD_CUBIC,
  GST_VIDEO_RESAMPLER_METHOD_SINC,
  GST_VIDEO_RESAMPLER_METHOD_LANCZOS
} GstVideoResamplerMethod;

Different subsampling and upsampling methods

`GST_VIDEO_RESAMPLER_METHOD_NEAREST`	Duplicates the samples when upsampling and drops when downsampling
`GST_VIDEO_RESAMPLER_METHOD_LINEAR`	Uses linear interpolation to reconstruct missing samples and averaging to downsample
`GST_VIDEO_RESAMPLER_METHOD_CUBIC`	Uses cubic interpolation
`GST_VIDEO_RESAMPLER_METHOD_SINC`	Uses sinc interpolation
`GST_VIDEO_RESAMPLER_METHOD_LANCZOS`	Uses lanczos interpolation

Since 1.6

gst_video_resampler_clear ()

void                gst_video_resampler_clear           (GstVideoResampler *resampler);

Clear a previously initialized GstVideoResampler resampler.

resampler :

a GstVideoResampler

Since 1.6

gst_video_resampler_init ()

gboolean            gst_video_resampler_init            (GstVideoResampler *resampler,
                                                         GstVideoResamplerMethod method,
                                                         GstVideoResamplerFlags flags,
                                                         guint n_phases,
                                                         guint n_taps,
                                                         gdouble shift,
                                                         guint in_size,
                                                         guint out_size,
                                                         GstStructure *options);

GST_VIDEO_RESAMPLER_OPT_CUBIC_B

#define GST_VIDEO_RESAMPLER_OPT_CUBIC_B      "GstVideoResampler.cubic-b"

G_TYPE_DOUBLE, B parameter of the cubic filter. The B parameter controls the bluriness. Values between 0.0 and 2.0 are accepted. 1/3 is the default.

Below are some values of popular filters: B C Hermite 0.0 0.0 Spline 1.0 0.0 Catmull-Rom 0.0 1/2 Mitchell 1/3 1/3 Robidoux 0.3782 0.3109 Robidoux Sharp 0.2620 0.3690 Robidoux Soft 0.6796 0.1602

GST_VIDEO_RESAMPLER_OPT_CUBIC_C

#define GST_VIDEO_RESAMPLER_OPT_CUBIC_C      "GstVideoResampler.cubic-c"

G_TYPE_DOUBLE, C parameter of the cubic filter. The C parameter controls the Keys alpha value. Values between 0.0 and 2.0 are accepted. 1/3 is the default.

See GST_VIDEO_RESAMPLER_OPT_CUBIC_B for some more common values

GST_VIDEO_RESAMPLER_OPT_ENVELOPE

#define GST_VIDEO_RESAMPLER_OPT_ENVELOPE      "GstVideoResampler.envelope"

G_TYPE_DOUBLE, specifies the size of filter envelope for GST_VIDEO_RESAMPLER_METHOD_LANCZOS. values are clamped between 1.0 and 5.0. 2.0 is the default.

GST_VIDEO_RESAMPLER_OPT_MAX_TAPS

#define GST_VIDEO_RESAMPLER_OPT_MAX_TAPS     "GstVideoResampler.max-taps"

G_TYPE_INT, limits the maximum number of taps to use. 16 is the default.

GST_VIDEO_RESAMPLER_OPT_SHARPEN

#define GST_VIDEO_RESAMPLER_OPT_SHARPEN      "GstVideoResampler.sharpen"

G_TYPE_DOUBLE, specifies sharpening of the filter for GST_VIDEO_RESAMPLER_METHOD_LANCZOS. values are clamped between 0.0 and 1.0. 0.0 is the default.

GST_VIDEO_RESAMPLER_OPT_SHARPNESS

#define GST_VIDEO_RESAMPLER_OPT_SHARPNESS     "GstVideoResampler.sharpness"

G_TYPE_DOUBLE, specifies sharpness of the filter for GST_VIDEO_RESAMPLER_METHOD_LANCZOS. values are clamped between 0.5 and 1.5. 1.0 is the default.

			GStreamer Base Plugins 1.0 Library Reference Manual
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