gavl
Typedefs | Functions
Scaler
Video

Video scaler. More...

Typedefs

typedef struct gavl_video_scaler_s gavl_video_scaler_t
 Opaque scaler structure.

Functions

GAVL_PUBLIC gavl_video_scaler_tgavl_video_scaler_create ()
 Create a video scaler.
GAVL_PUBLIC void gavl_video_scaler_destroy (gavl_video_scaler_t *scaler)
 Destroy a video scaler.
GAVL_PUBLIC gavl_video_options_tgavl_video_scaler_get_options (gavl_video_scaler_t *scaler)
 gets options of a scaler
GAVL_PUBLIC int gavl_video_scaler_init (gavl_video_scaler_t *scaler, const gavl_video_format_t *src_format, const gavl_video_format_t *dst_format)
 Initialize a video scaler.
GAVL_PUBLIC int gavl_video_scaler_init_convolve (gavl_video_scaler_t *scaler, const gavl_video_format_t *format, int h_radius, const float *h_coeffs, int v_radius, const float *v_coeffs)
 Initialize a video scaler as a generic convolver.
GAVL_PUBLIC void gavl_video_scaler_scale (gavl_video_scaler_t *scaler, const gavl_video_frame_t *input_frame, gavl_video_frame_t *output_frame)
 Scale video.

Detailed Description

Video scaler.

The scaler does the elementary operation to take a rectangular area of the source image and scale it into a specified rectangular area of the destination image. The source rectangle has floating point coordinates, the destination rectangle must have integer coordinates, which are aligned to chroma subsampling factors.

The internal scale tables are created for each plane and field separately. This means that:

You can use the scaler directly (through gavl_video_scaler_t). The generic video converter (gavl_video_converter_t) will create an internal scaler if necessary.


Typedef Documentation

typedef struct gavl_video_scaler_s gavl_video_scaler_t

Opaque scaler structure.

You don't want to know what's inside.


Function Documentation

GAVL_PUBLIC gavl_video_scaler_t* gavl_video_scaler_create ( )

Create a video scaler.

Returns:
A newly allocated video scaler
GAVL_PUBLIC void gavl_video_scaler_destroy ( gavl_video_scaler_t scaler)

Destroy a video scaler.

Parameters:
scalerA video scaler
GAVL_PUBLIC gavl_video_options_t* gavl_video_scaler_get_options ( gavl_video_scaler_t scaler)

gets options of a scaler

Parameters:
scalerA video scaler

After you called this, you can use the gavl_video_options_set_*() functions to change the options. Options will become valid with the next call to gavl_video_scaler_init

GAVL_PUBLIC int gavl_video_scaler_init ( gavl_video_scaler_t scaler,
const gavl_video_format_t src_format,
const gavl_video_format_t dst_format 
)

Initialize a video scaler.

Parameters:
scalerA video scaler
src_formatInput format
dst_formatOutput format
Returns:
If something goes wrong (should never happen), -1 is returned.

You should have equal pixelformats in the source and destination. This function can be called multiple times with one instance.

GAVL_PUBLIC int gavl_video_scaler_init_convolve ( gavl_video_scaler_t scaler,
const gavl_video_format_t format,
int  h_radius,
const float *  h_coeffs,
int  v_radius,
const float *  v_coeffs 
)

Initialize a video scaler as a generic convolver.

Parameters:
scalerA video scaler
formatFormat (must be the same for input and output)
h_radiusHorizontal radius
h_coeffsHorizontal coefficients
v_radiusVertical radius
v_coeffsVertical coefficients
Returns:
If something goes wrong (should never happen), -1 is returned.

This initialized a scaler for use as a generic convolver. The h_radius and v_radius arguments denote the numbers of pixels, which are taken in both left and right from the center pixel, i.e. a value of 1 will result in a 3-tap filter. The coefficients must be given for ALL taps (the convolver does not assume the coeffitients to be symmetric)

This function can be called multiple times with one instance.

GAVL_PUBLIC void gavl_video_scaler_scale ( gavl_video_scaler_t scaler,
const gavl_video_frame_t input_frame,
gavl_video_frame_t output_frame 
)

Scale video.

Parameters:
scalerA video scaler
input_frameInput frame
output_frameOutput frame