GstVideoResampler: GStreamer Base Plugins 1.0 Library Reference Manual

GstVideoResampler

GstVideoResampler — Utility structure for resampler information

Functions

void	gst_video_resampler_clear ()
gboolean	gst_video_resampler_init ()

Types and Values

struct	GstVideoResampler
enum	GstVideoResamplerFlags
enum	GstVideoResamplerMethod
#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

Includes

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

Description

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

Functions

gst_video_resampler_clear ()

void
gst_video_resampler_clear (GstVideoResampler *resampler);

Clear a previously initialized GstVideoResampler resampler .

Parameters

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);

Types and Values

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.

Members

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

Different resampler flags.

Members

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

Different subsampling and upsampling methods

Members

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_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.