Color conversion and scaling library. More...

Files
file	swscale.h
	external API header

Data Structures
struct	SwsVector

struct	SwsFilter

Macros
#define	SWS_FAST_BILINEAR 1

#define	SWS_BILINEAR 2

#define	SWS_BICUBIC 4

#define	SWS_X 8

#define	SWS_POINT 0x10

#define	SWS_AREA 0x20

#define	SWS_BICUBLIN 0x40

#define	SWS_GAUSS 0x80

#define	SWS_SINC 0x100

#define	SWS_LANCZOS 0x200

#define	SWS_SPLINE 0x400

#define	SWS_SRC_V_CHR_DROP_MASK 0x30000

#define	SWS_SRC_V_CHR_DROP_SHIFT 16

#define	SWS_PARAM_DEFAULT 123456

#define	SWS_PRINT_INFO 0x1000

#define	SWS_FULL_CHR_H_INT 0x2000

#define	SWS_FULL_CHR_H_INP 0x4000

#define	SWS_DIRECT_BGR 0x8000

#define	SWS_ACCURATE_RND 0x40000

#define	SWS_BITEXACT 0x80000

#define	SWS_ERROR_DIFFUSION 0x800000

#define	SWS_MAX_REDUCE_CUTOFF 0.002

#define	SWS_CS_ITU709 1

#define	SWS_CS_FCC 4

#define	SWS_CS_ITU601 5

#define	SWS_CS_ITU624 5

#define	SWS_CS_SMPTE170M 5

#define	SWS_CS_SMPTE240M 7

#define	SWS_CS_DEFAULT 5

#define	SWS_CS_BT2020 9

Functions
unsigned	swscale_version (void)

const char *	swscale_configuration (void)
	Return the libswscale build-time configuration. More...

const char *	swscale_license (void)
	Return the libswscale license. More...

const int *	sws_getCoefficients (int colorspace)
	Return a pointer to yuv<->rgb coefficients for the given colorspace suitable for sws_setColorspaceDetails(). More...

int	sws_isSupportedInput (enum AVPixelFormat pix_fmt)
	Return a positive value if pix_fmt is a supported input format, 0 otherwise. More...

int	sws_isSupportedOutput (enum AVPixelFormat pix_fmt)
	Return a positive value if pix_fmt is a supported output format, 0 otherwise. More...

int	sws_isSupportedEndiannessConversion (enum AVPixelFormat pix_fmt)

struct SwsContext *	sws_alloc_context (void)
	Allocate an empty SwsContext. More...

av_warn_unused_result int	sws_init_context (struct SwsContext sws_context, SwsFilter srcFilter, SwsFilter *dstFilter)
	Initialize the swscaler context sws_context. More...

void	sws_freeContext (struct SwsContext *swsContext)
	Free the swscaler context swsContext. More...

struct SwsContext *	sws_getContext (int srcW, int srcH, enum AVPixelFormat srcFormat, int dstW, int dstH, enum AVPixelFormat dstFormat, int flags, SwsFilter srcFilter, SwsFilter dstFilter, const double *param)
	Allocate and return an SwsContext. More...

int	sws_scale (struct SwsContext c, const uint8_t const srcSlice[], const int srcStride[], int srcSliceY, int srcSliceH, uint8_t *const dst[], const int dstStride[])
	Scale the image slice in srcSlice and put the resulting scaled slice in the image in dst. More...

int	sws_scale_frame (struct SwsContext c, AVFrame dst, const AVFrame *src)
	Scale source data from src and write the output to dst. More...

int	sws_frame_start (struct SwsContext c, AVFrame dst, const AVFrame *src)
	Initialize the scaling process for a given pair of source/destination frames. More...

void	sws_frame_end (struct SwsContext *c)
	Finish the scaling process for a pair of source/destination frames previously submitted with sws_frame_start(). More...

int	sws_send_slice (struct SwsContext *c, unsigned int slice_start, unsigned int slice_height)
	Indicate that a horizontal slice of input data is available in the source frame previously provided to sws_frame_start(). More...

int	sws_receive_slice (struct SwsContext *c, unsigned int slice_start, unsigned int slice_height)
	Request a horizontal slice of the output data to be written into the frame previously provided to sws_frame_start(). More...

unsigned int	sws_receive_slice_alignment (const struct SwsContext *c)

int	sws_setColorspaceDetails (struct SwsContext *c, const int inv_table[4], int srcRange, const int table[4], int dstRange, int brightness, int contrast, int saturation)

int	sws_getColorspaceDetails (struct SwsContext c, int inv_table, int srcRange, int *table, int dstRange, int brightness, int contrast, int *saturation)
	#if LIBSWSCALE_VERSION_MAJOR > 6 More...

SwsVector *	sws_allocVec (int length)
	Allocate and return an uninitialized vector with length coefficients. More...

SwsVector *	sws_getGaussianVec (double variance, double quality)
	Return a normalized Gaussian curve used to filter stuff quality = 3 is high quality, lower is lower quality. More...

void	sws_scaleVec (SwsVector *a, double scalar)
	Scale all the coefficients of a by the scalar value. More...

void	sws_normalizeVec (SwsVector *a, double height)
	Scale all the coefficients of a so that their sum equals height. More...

void	sws_freeVec (SwsVector *a)

SwsFilter *	sws_getDefaultFilter (float lumaGBlur, float chromaGBlur, float lumaSharpen, float chromaSharpen, float chromaHShift, float chromaVShift, int verbose)

void	sws_freeFilter (SwsFilter *filter)

struct SwsContext *	sws_getCachedContext (struct SwsContext context, int srcW, int srcH, enum AVPixelFormat srcFormat, int dstW, int dstH, enum AVPixelFormat dstFormat, int flags, SwsFilter srcFilter, SwsFilter dstFilter, const double param)
	Check if context can be reused, otherwise reallocate a new one. More...

void	sws_convertPalette8ToPacked32 (const uint8_t src, uint8_t dst, int num_pixels, const uint8_t *palette)
	Convert an 8-bit paletted frame into a frame with a color depth of 32 bits. More...

void	sws_convertPalette8ToPacked24 (const uint8_t src, uint8_t dst, int num_pixels, const uint8_t *palette)
	Convert an 8-bit paletted frame into a frame with a color depth of 24 bits. More...

const AVClass *	sws_get_class (void)
	Get the AVClass for swsContext. More...

Detailed Description

Color conversion and scaling library.

Return the LIBSWSCALE_VERSION_INT constant.

Macro Definition Documentation

◆ SWS_FAST_BILINEAR

#define SWS_FAST_BILINEAR 1

Definition at line 65 of file swscale.h.

◆ SWS_BILINEAR

#define SWS_BILINEAR 2

Examples: scaling_video.c.

Definition at line 66 of file swscale.h.

◆ SWS_BICUBIC

#define SWS_BICUBIC 4

Definition at line 67 of file swscale.h.

◆ SWS_X

#define SWS_X 8

Definition at line 68 of file swscale.h.

◆ SWS_POINT

#define SWS_POINT 0x10

Definition at line 69 of file swscale.h.

◆ SWS_AREA

#define SWS_AREA 0x20

Definition at line 70 of file swscale.h.

◆ SWS_BICUBLIN

#define SWS_BICUBLIN 0x40

Definition at line 71 of file swscale.h.

◆ SWS_GAUSS

#define SWS_GAUSS 0x80

Definition at line 72 of file swscale.h.

◆ SWS_SINC

#define SWS_SINC 0x100

Definition at line 73 of file swscale.h.

◆ SWS_LANCZOS

#define SWS_LANCZOS 0x200

Definition at line 74 of file swscale.h.

◆ SWS_SPLINE

#define SWS_SPLINE 0x400

Definition at line 75 of file swscale.h.

◆ SWS_SRC_V_CHR_DROP_MASK

#define SWS_SRC_V_CHR_DROP_MASK 0x30000

Definition at line 77 of file swscale.h.

◆ SWS_SRC_V_CHR_DROP_SHIFT

#define SWS_SRC_V_CHR_DROP_SHIFT 16

Definition at line 78 of file swscale.h.

◆ SWS_PARAM_DEFAULT

#define SWS_PARAM_DEFAULT 123456

Definition at line 80 of file swscale.h.

◆ SWS_PRINT_INFO

#define SWS_PRINT_INFO 0x1000

Definition at line 82 of file swscale.h.

◆ SWS_FULL_CHR_H_INT

#define SWS_FULL_CHR_H_INT 0x2000

Definition at line 86 of file swscale.h.

◆ SWS_FULL_CHR_H_INP

#define SWS_FULL_CHR_H_INP 0x4000

Definition at line 88 of file swscale.h.

◆ SWS_DIRECT_BGR

#define SWS_DIRECT_BGR 0x8000

Definition at line 89 of file swscale.h.

◆ SWS_ACCURATE_RND

#define SWS_ACCURATE_RND 0x40000

Definition at line 90 of file swscale.h.

◆ SWS_BITEXACT

#define SWS_BITEXACT 0x80000

Definition at line 91 of file swscale.h.

◆ SWS_ERROR_DIFFUSION

#define SWS_ERROR_DIFFUSION 0x800000

Definition at line 92 of file swscale.h.

◆ SWS_MAX_REDUCE_CUTOFF

#define SWS_MAX_REDUCE_CUTOFF 0.002

Definition at line 94 of file swscale.h.

◆ SWS_CS_ITU709

#define SWS_CS_ITU709 1

Definition at line 96 of file swscale.h.

◆ SWS_CS_FCC

#define SWS_CS_FCC 4

Definition at line 97 of file swscale.h.

◆ SWS_CS_ITU601

#define SWS_CS_ITU601 5

Definition at line 98 of file swscale.h.

◆ SWS_CS_ITU624

#define SWS_CS_ITU624 5

Definition at line 99 of file swscale.h.

◆ SWS_CS_SMPTE170M

#define SWS_CS_SMPTE170M 5

Definition at line 100 of file swscale.h.

◆ SWS_CS_SMPTE240M

#define SWS_CS_SMPTE240M 7

Definition at line 101 of file swscale.h.

◆ SWS_CS_DEFAULT

#define SWS_CS_DEFAULT 5

Definition at line 102 of file swscale.h.

◆ SWS_CS_BT2020

#define SWS_CS_BT2020 9

Definition at line 103 of file swscale.h.

Function Documentation

◆ swscale_version()

unsigned swscale_version ( void )

◆ swscale_configuration()

const char * swscale_configuration ( void )

Return the libswscale build-time configuration.

◆ swscale_license()

const char * swscale_license ( void )

Return the libswscale license.

◆ sws_getCoefficients()

const int * sws_getCoefficients ( int colorspace )

Return a pointer to yuv<->rgb coefficients for the given colorspace suitable for sws_setColorspaceDetails().

Parameters

colorspace One of the SWS_CS_* macros. If invalid, SWS_CS_DEFAULT is used.

◆ sws_isSupportedInput()

int sws_isSupportedInput ( enum AVPixelFormat pix_fmt )

Return a positive value if pix_fmt is a supported input format, 0 otherwise.

◆ sws_isSupportedOutput()

int sws_isSupportedOutput ( enum AVPixelFormat pix_fmt )

Return a positive value if pix_fmt is a supported output format, 0 otherwise.

◆ sws_isSupportedEndiannessConversion()

int sws_isSupportedEndiannessConversion ( enum AVPixelFormat pix_fmt )

Parameters

[in] pix_fmt the pixel format

Returns: a positive value if an endianness conversion for pix_fmt is supported, 0 otherwise.

◆ sws_alloc_context()

struct SwsContext * sws_alloc_context ( void )

Allocate an empty SwsContext.

This must be filled and passed to sws_init_context(). For filling see AVOptions, options.c and sws_setColorspaceDetails().

◆ sws_init_context()

av_warn_unused_result int sws_init_context	(	struct SwsContext *	sws_context,
		SwsFilter *	srcFilter,
		SwsFilter *	dstFilter
	)

Initialize the swscaler context sws_context.

Returns: zero or positive value on success, a negative value on error

◆ sws_freeContext()

void sws_freeContext ( struct SwsContext * swsContext )

Free the swscaler context swsContext.

If swsContext is NULL, then does nothing.

Examples: muxing.c, and scaling_video.c.

Referenced by close_stream(), and main().

◆ sws_getContext()

struct SwsContext * sws_getContext	(	int	srcW,
		int	srcH,
		enum AVPixelFormat	srcFormat,
		int	dstW,
		int	dstH,
		enum AVPixelFormat	dstFormat,
		int	flags,
		SwsFilter *	srcFilter,
		SwsFilter *	dstFilter,
		const double *	param
	)

Allocate and return an SwsContext.

You need it to perform scaling/conversion operations using sws_scale().

Parameters

srcW	the width of the source image
srcH	the height of the source image
srcFormat	the source image format
dstW	the width of the destination image
dstH	the height of the destination image
dstFormat	the destination image format
flags	specify which algorithm and options to use for rescaling
param	extra parameters to tune the used scaler For SWS_BICUBIC param[0] and [1] tune the shape of the basis function, param[0] tunes f(1) and param[1] f´(1) For SWS_GAUSS param[0] tunes the exponent and thus cutoff frequency For SWS_LANCZOS param[0] tunes the width of the window function

Returns: a pointer to an allocated context, or NULL in case of error

Note: this function is to be removed after a saner alternative is written

Examples: muxing.c, and scaling_video.c.

Referenced by get_video_frame(), and main().

◆ sws_scale()

int sws_scale	(	struct SwsContext *	c,
		const uint8_t *const	srcSlice[],
		const int	srcStride[],
		int	srcSliceY,
		int	srcSliceH,
		uint8_t *const	dst[],
		const int	dstStride[]
	)

Scale the image slice in srcSlice and put the resulting scaled slice in the image in dst.

A slice is a sequence of consecutive rows in an image.

Slices have to be provided in sequential order, either in top-bottom or bottom-top order. If slices are provided in non-sequential order the behavior of the function is undefined.

Parameters

c	the scaling context previously created with sws_getContext()
srcSlice	the array containing the pointers to the planes of the source slice
srcStride	the array containing the strides for each plane of the source image
srcSliceY	the position in the source image of the slice to process, that is the number (counted starting from zero) in the image of the first row of the slice
srcSliceH	the height of the source slice, that is the number of rows in the slice
dst	the array containing the pointers to the planes of the destination image
dstStride	the array containing the strides for each plane of the destination image

Returns: the height of the output slice

Examples: muxing.c, and scaling_video.c.

Referenced by get_video_frame(), and main().

◆ sws_scale_frame()

int sws_scale_frame	(	struct SwsContext *	c,
		AVFrame *	dst,
		const AVFrame *	src
	)

Scale source data from src and write the output to dst.

This is merely a convenience wrapper around

sws_frame_start()
sws_send_slice(0, src->height)
sws_receive_slice(0, dst->height)
sws_frame_end()

Parameters

dst	The destination frame. See documentation for sws_frame_start() for more details.
src	The source frame.

Returns: 0 on success, a negative AVERROR code on failure

◆ sws_frame_start()

int sws_frame_start	(	struct SwsContext *	c,
		AVFrame *	dst,
		const AVFrame *	src
	)

Initialize the scaling process for a given pair of source/destination frames.

Must be called before any calls to sws_send_slice() and sws_receive_slice().

This function will retain references to src and dst, so they must both use refcounted buffers (if allocated by the caller, in case of dst).

Parameters

dst

The destination frame.

       The data buffers may either be already allocated by the caller or
       left clear, in which case they will be allocated by the scaler.
       The latter may have performance advantages - e.g. in certain cases
       some output planes may be references to input planes, rather than
       copies.

       Output data will be written into this frame in successful
       sws_receive_slice() calls.

src The source frame. The data buffers must be allocated, but the frame data does not have to be ready at this point. Data availability is then signalled by sws_send_slice().

Returns: 0 on success, a negative AVERROR code on failure

See also: sws_frame_end()

◆ sws_frame_end()

void sws_frame_end ( struct SwsContext * c )

Finish the scaling process for a pair of source/destination frames previously submitted with sws_frame_start().

Must be called after all sws_send_slice() and sws_receive_slice() calls are done, before any new sws_frame_start() calls.

◆ sws_send_slice()

int sws_send_slice	(	struct SwsContext *	c,
		unsigned int	slice_start,
		unsigned int	slice_height
	)

Indicate that a horizontal slice of input data is available in the source frame previously provided to sws_frame_start().

The slices may be provided in any order, but may not overlap. For vertically subsampled pixel formats, the slices must be aligned according to subsampling.

Parameters

slice_start	first row of the slice
slice_height	number of rows in the slice

Returns: a non-negative number on success, a negative AVERROR code on failure.

◆ sws_receive_slice()

int sws_receive_slice	(	struct SwsContext *	c,
		unsigned int	slice_start,
		unsigned int	slice_height
	)

Request a horizontal slice of the output data to be written into the frame previously provided to sws_frame_start().

Parameters

slice_start	first row of the slice; must be a multiple of sws_receive_slice_alignment()
slice_height	number of rows in the slice; must be a multiple of sws_receive_slice_alignment(), except for the last slice (i.e. when slice_start+slice_height is equal to output frame height)

Returns: a non-negative number if the data was successfully written into the output AVERROR(EAGAIN) if more input data needs to be provided before the output can be produced another negative AVERROR code on other kinds of scaling failure

◆ sws_receive_slice_alignment()

unsigned int sws_receive_slice_alignment ( const struct SwsContext * c )

Returns: alignment required for output slices requested with sws_receive_slice(). Slice offsets and sizes passed to sws_receive_slice() must be multiples of the value returned from this function.

◆ sws_setColorspaceDetails()

int sws_setColorspaceDetails	(	struct SwsContext *	c,
		const int	inv_table[4],
		int	srcRange,
		const int	table[4],
		int	dstRange,
		int	brightness,
		int	contrast,
		int	saturation
	)

Parameters

dstRange	flag indicating the while-black range of the output (1=jpeg / 0=mpeg)
srcRange	flag indicating the while-black range of the input (1=jpeg / 0=mpeg)
table	the yuv2rgb coefficients describing the output yuv space, normally ff_yuv2rgb_coeffs[x]
inv_table	the yuv2rgb coefficients describing the input yuv space, normally ff_yuv2rgb_coeffs[x]
brightness	16.16 fixed point brightness correction
contrast	16.16 fixed point contrast correction
saturation	16.16 fixed point saturation correction #if LIBSWSCALE_VERSION_MAJOR > 6

Returns: negative error code on error, non negative otherwise #else; -1 if not supported #endif

◆ sws_getColorspaceDetails()

int sws_getColorspaceDetails	(	struct SwsContext *	c,
		int **	inv_table,
		int *	srcRange,
		int **	table,
		int *	dstRange,
		int *	brightness,
		int *	contrast,
		int *	saturation
	)

#if LIBSWSCALE_VERSION_MAJOR > 6

Returns: negative error code on error, non negative otherwise #else; -1 if not supported #endif

◆ sws_allocVec()

SwsVector * sws_allocVec ( int length )

Allocate and return an uninitialized vector with length coefficients.

◆ sws_getGaussianVec()

SwsVector * sws_getGaussianVec	(	double	variance,
		double	quality
	)

Return a normalized Gaussian curve used to filter stuff quality = 3 is high quality, lower is lower quality.

◆ sws_scaleVec()

void sws_scaleVec	(	SwsVector *	a,
		double	scalar
	)

Scale all the coefficients of a by the scalar value.

◆ sws_normalizeVec()

void sws_normalizeVec	(	SwsVector *	a,
		double	height
	)

Scale all the coefficients of a so that their sum equals height.

◆ sws_freeVec()

void sws_freeVec ( SwsVector * a )

◆ sws_getDefaultFilter()

SwsFilter * sws_getDefaultFilter	(	float	lumaGBlur,
		float	chromaGBlur,
		float	lumaSharpen,
		float	chromaSharpen,
		float	chromaHShift,
		float	chromaVShift,
		int	verbose
	)

◆ sws_freeFilter()

void sws_freeFilter ( SwsFilter * filter )

◆ sws_getCachedContext()

struct SwsContext * sws_getCachedContext	(	struct SwsContext *	context,
		int	srcW,
		int	srcH,
		enum AVPixelFormat	srcFormat,
		int	dstW,
		int	dstH,
		enum AVPixelFormat	dstFormat,
		int	flags,
		SwsFilter *	srcFilter,
		SwsFilter *	dstFilter,
		const double *	param
	)

Check if context can be reused, otherwise reallocate a new one.

If context is NULL, just calls sws_getContext() to get a new context. Otherwise, checks if the parameters are the ones already saved in context. If that is the case, returns the current context. Otherwise, frees context and gets a new context with the new parameters.

Be warned that srcFilter and dstFilter are not checked, they are assumed to remain the same.

◆ sws_convertPalette8ToPacked32()

void sws_convertPalette8ToPacked32	(	const uint8_t *	src,
		uint8_t *	dst,
		int	num_pixels,
		const uint8_t *	palette
	)

Convert an 8-bit paletted frame into a frame with a color depth of 32 bits.

The output frame will have the same packed format as the palette.

Parameters

src	source frame buffer
dst	destination frame buffer
num_pixels	number of pixels to convert
palette	array with [256] entries, which must match color arrangement (RGB or BGR) of src

◆ sws_convertPalette8ToPacked24()

void sws_convertPalette8ToPacked24	(	const uint8_t *	src,
		uint8_t *	dst,
		int	num_pixels,
		const uint8_t *	palette
	)

Convert an 8-bit paletted frame into a frame with a color depth of 24 bits.

With the palette format "ABCD", the destination frame ends up with the format "ABC".

Parameters

src	source frame buffer
dst	destination frame buffer
num_pixels	number of pixels to convert
palette	array with [256] entries, which must match color arrangement (RGB or BGR) of src

◆ sws_get_class()

const AVClass * sws_get_class ( void )

Get the AVClass for swsContext.

It can be used in combination with AV_OPT_SEARCH_FAKE_OBJ for examining options.

See also: av_opt_find().

Files

Data Structures

Macros

Functions

Detailed Description

Macro Definition Documentation

◆ SWS_FAST_BILINEAR

◆ SWS_BILINEAR

◆ SWS_BICUBIC

◆ SWS_X

◆ SWS_POINT

◆ SWS_AREA

◆ SWS_BICUBLIN

◆ SWS_GAUSS

◆ SWS_SINC

◆ SWS_LANCZOS

◆ SWS_SPLINE

◆ SWS_SRC_V_CHR_DROP_MASK

◆ SWS_SRC_V_CHR_DROP_SHIFT

◆ SWS_PARAM_DEFAULT

◆ SWS_PRINT_INFO

◆ SWS_FULL_CHR_H_INT

◆ SWS_FULL_CHR_H_INP

◆ SWS_DIRECT_BGR

◆ SWS_ACCURATE_RND

◆ SWS_BITEXACT

◆ SWS_ERROR_DIFFUSION

◆ SWS_MAX_REDUCE_CUTOFF

◆ SWS_CS_ITU709

◆ SWS_CS_FCC

◆ SWS_CS_ITU601

◆ SWS_CS_ITU624

◆ SWS_CS_SMPTE170M

◆ SWS_CS_SMPTE240M

◆ SWS_CS_DEFAULT

◆ SWS_CS_BT2020

Function Documentation

◆ swscale_version()

◆ swscale_configuration()

◆ swscale_license()

◆ sws_getCoefficients()

◆ sws_isSupportedInput()

◆ sws_isSupportedOutput()

◆ sws_isSupportedEndiannessConversion()

◆ sws_alloc_context()

◆ sws_init_context()

◆ sws_freeContext()

◆ sws_getContext()

◆ sws_scale()

◆ sws_scale_frame()

◆ sws_frame_start()

◆ sws_frame_end()

◆ sws_send_slice()

◆ sws_receive_slice()

◆ sws_receive_slice_alignment()

◆ sws_setColorspaceDetails()

◆ sws_getColorspaceDetails()

◆ sws_allocVec()

◆ sws_getGaussianVec()

◆ sws_scaleVec()

◆ sws_normalizeVec()

◆ sws_freeVec()

◆ sws_getDefaultFilter()

◆ sws_freeFilter()

◆ sws_getCachedContext()

◆ sws_convertPalette8ToPacked32()

◆ sws_convertPalette8ToPacked24()

◆ sws_get_class()