SwsContext Struct Reference

Public Member Functions
	DECLARE_ALIGNED (16, int, table_gV)[256+2 *YUVRGB_TABLE_HEADROOM]
	DECLARE_ALIGNED (16, int32_t, input_rgb2yuv_table)[16+40 *4]
	DECLARE_ALIGNED (8, uint64_t, redDither)
	DECLARE_ALIGNED (8, uint64_t, greenDither)
	DECLARE_ALIGNED (8, uint64_t, blueDither)
	DECLARE_ALIGNED (8, uint64_t, yCoeff)
	DECLARE_ALIGNED (8, uint64_t, vrCoeff)
	DECLARE_ALIGNED (8, uint64_t, ubCoeff)
	DECLARE_ALIGNED (8, uint64_t, vgCoeff)
	DECLARE_ALIGNED (8, uint64_t, ugCoeff)
	DECLARE_ALIGNED (8, uint64_t, yOffset)
	DECLARE_ALIGNED (8, uint64_t, uOffset)
	DECLARE_ALIGNED (8, uint64_t, vOffset)
	DECLARE_ALIGNED (8, uint64_t, esp)
	DECLARE_ALIGNED (8, uint64_t, vRounder)
	DECLARE_ALIGNED (8, uint64_t, u_temp)
	DECLARE_ALIGNED (8, uint64_t, v_temp)
	DECLARE_ALIGNED (8, uint64_t, y_temp)
	DECLARE_ALIGNED (8, ptrdiff_t, uv_off)
	offset (in pixels) between u and v planes
	DECLARE_ALIGNED (8, ptrdiff_t, uv_offx2)
	offset (in bytes) between u and v planes
	DECLARE_ALIGNED (8, uint16_t, dither16)[8]
	DECLARE_ALIGNED (8, uint32_t, dither32)[8]

Public Attributes
const AVClass *	av_class
	info on struct for av_log
SwsFunc	swscale
	Note that src, dst, srcStride, dstStride will be copied in the sws_scale() wrapper so they can be freely modified here.
int	srcW
	Width of source luma/alpha planes.
int	srcH
	Height of source luma/alpha planes.
int	dstH
	Height of destination luma/alpha planes.
int	chrSrcW
	Width of source chroma planes.
int	chrSrcH
	Height of source chroma planes.
int	chrDstW
	Width of destination chroma planes.
int	chrDstH
	Height of destination chroma planes.
int	lumXInc
int	chrXInc
int	lumYInc
int	chrYInc
enum AVPixelFormat	dstFormat
	Destination pixel format.
enum AVPixelFormat	srcFormat
	Source pixel format.
int	dstFormatBpp
	Number of bits per pixel of the destination pixel format.
int	srcFormatBpp
	Number of bits per pixel of the source pixel format.
int	dstBpc
int	srcBpc
int	chrSrcHSubSample
	Binary logarithm of horizontal subsampling factor between luma/alpha and chroma planes in source image.
int	chrSrcVSubSample
	Binary logarithm of vertical subsampling factor between luma/alpha and chroma planes in source image.
int	chrDstHSubSample
	Binary logarithm of horizontal subsampling factor between luma/alpha and chroma planes in destination image.
int	chrDstVSubSample
	Binary logarithm of vertical subsampling factor between luma/alpha and chroma planes in destination image.
int	vChrDrop
	Binary logarithm of extra vertical subsampling factor in source image chroma planes specified by user.
int	sliceDir
	Direction that slices are fed to the scaler (1 = top-to-bottom, -1 = bottom-to-top).
double	param [2]
	Input parameters for scaling algorithms that need them.
struct SwsContext *	cascaded_context [3]
int	cascaded_tmpStride [4]
uint8_t *	cascaded_tmp [4]
int	cascaded1_tmpStride [4]
uint8_t *	cascaded1_tmp [4]
int	cascaded_mainindex
double	gamma_value
int	gamma_flag
int	is_internal_gamma
uint16_t *	gamma
uint16_t *	inv_gamma
int	numDesc
int	descIndex [2]
int	numSlice
struct SwsSlice *	slice
struct SwsFilterDescriptor *	desc
uint32_t	pal_yuv [256]
uint32_t	pal_rgb [256]
uint8_t *	formatConvBuffer
int	needAlpha
int	lumMmxextFilterCodeSize
	Runtime-generated MMXEXT horizontal fast bilinear scaler code size for luma/alpha planes.
int	chrMmxextFilterCodeSize
	Runtime-generated MMXEXT horizontal fast bilinear scaler code size for chroma planes.
uint8_t *	lumMmxextFilterCode
	Runtime-generated MMXEXT horizontal fast bilinear scaler code for luma/alpha planes.
uint8_t *	chrMmxextFilterCode
	Runtime-generated MMXEXT horizontal fast bilinear scaler code for chroma planes.
int	canMMXEXTBeUsed
int	warned_unuseable_bilinear
int	dstY
	Last destination vertical line output from last slice.
int	flags
	Flags passed by the user to select scaler algorithm, optimizations, subsampling, etc...
void *	yuvTable
uint8_t *	table_rV [256+2 *YUVRGB_TABLE_HEADROOM]
uint8_t *	table_gU [256+2 *YUVRGB_TABLE_HEADROOM]
uint8_t *	table_bU [256+2 *YUVRGB_TABLE_HEADROOM]
int *	dither_error [4]
int	contrast
int	brightness
int	saturation
int	srcColorspaceTable [4]
int	dstColorspaceTable [4]
int	srcRange
	0 = MPG YUV range, 1 = JPG YUV range (source image).
int	dstRange
	0 = MPG YUV range, 1 = JPG YUV range (destination image).
int	src0Alpha
int	dst0Alpha
int	srcXYZ
int	dstXYZ
int	src_h_chr_pos
int	dst_h_chr_pos
int	src_v_chr_pos
int	dst_v_chr_pos
int	yuv2rgb_y_offset
int	yuv2rgb_y_coeff
int	yuv2rgb_v2r_coeff
int	yuv2rgb_v2g_coeff
int	yuv2rgb_u2g_coeff
int	yuv2rgb_u2b_coeff
int32_t	lumMmxFilter [4 *MAX_FILTER_SIZE]
int32_t	chrMmxFilter [4 *MAX_FILTER_SIZE]
int	dstW
	Width of destination luma/alpha planes.
int32_t	alpMmxFilter [4 *MAX_FILTER_SIZE]
const uint8_t *	chrDither8
const uint8_t *	lumDither8
int	use_mmx_vfilter
int16_t *	xyzgamma
int16_t *	rgbgamma
int16_t *	xyzgammainv
int16_t *	rgbgammainv
int16_t	xyz2rgb_matrix [3][4]
int16_t	rgb2xyz_matrix [3][4]
yuv2planar1_fn	yuv2plane1
yuv2planarX_fn	yuv2planeX
yuv2interleavedX_fn	yuv2nv12cX
yuv2packed1_fn	yuv2packed1
yuv2packed2_fn	yuv2packed2
yuv2packedX_fn	yuv2packedX
yuv2anyX_fn	yuv2anyX
void(*	lumToYV12 )(uint8_t *dst, const uint8_t *src, const uint8_t *src2, const uint8_t *src3, int width, uint32_t *pal)
	Unscaled conversion of luma plane to YV12 for horizontal scaler.
void(*	alpToYV12 )(uint8_t *dst, const uint8_t *src, const uint8_t *src2, const uint8_t *src3, int width, uint32_t *pal)
	Unscaled conversion of alpha plane to YV12 for horizontal scaler.
void(*	chrToYV12 )(uint8_t *dstU, uint8_t *dstV, const uint8_t *src1, const uint8_t *src2, const uint8_t *src3, int width, uint32_t *pal)
	Unscaled conversion of chroma planes to YV12 for horizontal scaler.
void(*	lumConvertRange )(int16_t *dst, int width)
	Color range conversion function for luma plane if needed.
void(*	chrConvertRange )(int16_t *dst1, int16_t *dst2, int width)
	Color range conversion function for chroma planes if needed.
int	needs_hcscale
	Set if there are chroma planes to be converted.
SwsDither	dither
SwsAlphaBlend	alphablend
Scaled horizontal lines ring buffer.
The horizontal scaler keeps just enough scaled lines in a ring buffer so they may be passed to the vertical scaler. The pointers to the allocated buffers for each line are duplicated in sequence in the ring buffer to simplify indexing and avoid wrapping around between lines inside the vertical scaler code. The wrapping is done before the vertical scaler is called.
int	lastInLumBuf
	Last scaled horizontal luma/alpha line from source in the ring buffer.
int	lastInChrBuf
	Last scaled horizontal chroma line from source in the ring buffer.
int	lumBufIndex
	Index in ring buffer of the last scaled horizontal luma/alpha line from source.
int	chrBufIndex
	Index in ring buffer of the last scaled horizontal chroma line from source.
Horizontal and vertical filters.
To better understand the following fields, here is a pseudo-code of their usage in filtering a horizontal line: for (i = 0; i < width; i++) { dst[i] = 0; for (j = 0; j < filterSize; j++) dst[i] += src[ filterPos[i] + j ] * filter[ filterSize * i + j ]; dst[i] >>= FRAC_BITS; // The actual implementation is fixed-point. }
int16_t *	hLumFilter
	Array of horizontal filter coefficients for luma/alpha planes.
int16_t *	hChrFilter
	Array of horizontal filter coefficients for chroma planes.
int16_t *	vLumFilter
	Array of vertical filter coefficients for luma/alpha planes.
int16_t *	vChrFilter
	Array of vertical filter coefficients for chroma planes.
int32_t *	hLumFilterPos
	Array of horizontal filter starting positions for each dst[i] for luma/alpha planes.
int32_t *	hChrFilterPos
	Array of horizontal filter starting positions for each dst[i] for chroma planes.
int32_t *	vLumFilterPos
	Array of vertical filter starting positions for each dst[i] for luma/alpha planes.
int32_t *	vChrFilterPos
	Array of vertical filter starting positions for each dst[i] for chroma planes.
int	hLumFilterSize
	Horizontal filter size for luma/alpha pixels.
int	hChrFilterSize
	Horizontal filter size for chroma pixels.
int	vLumFilterSize
	Vertical filter size for luma/alpha pixels.
int	vChrFilterSize
	Vertical filter size for chroma pixels.
void(*	readLumPlanar )(uint8_t *dst, const uint8_t *src[4], int width, int32_t *rgb2yuv)
	Functions to read planar input, such as planar RGB, and convert internally to Y/UV/A.
void(*	readChrPlanar )(uint8_t *dstU, uint8_t *dstV, const uint8_t *src[4], int width, int32_t *rgb2yuv)
void(*	readAlpPlanar )(uint8_t *dst, const uint8_t *src[4], int width, int32_t *rgb2yuv)
void(*	hyscale_fast )(struct SwsContext *c, int16_t *dst, int dstWidth, const uint8_t *src, int srcW, int xInc)
	Scale one horizontal line of input data using a bilinear filter to produce one line of output data. More...
void(*	hcscale_fast )(struct SwsContext *c, int16_t *dst1, int16_t *dst2, int dstWidth, const uint8_t *src1, const uint8_t *src2, int srcW, int xInc)
void(*	hyScale )(struct SwsContext *c, int16_t *dst, int dstW, const uint8_t *src, const int16_t *filter, const int32_t *filterPos, int filterSize)
	Scale one horizontal line of input data using a filter over the input lines, to produce one (differently sized) line of output data. More...
void(*	hcScale )(struct SwsContext *c, int16_t *dst, int dstW, const uint8_t *src, const int16_t *filter, const int32_t *filterPos, int filterSize)

Member Data Documentation

hyScale

void(* SwsContext::hyScale) (struct SwsContext *c, int16_t *dst, int dstW, const uint8_t *src, const int16_t *filter, const int32_t *filterPos, int filterSize)

Scale one horizontal line of input data using a filter over the input lines, to produce one (differently sized) line of output data.

Parameters

dst	pointer to destination buffer for horizontally scaled data. If the number of bits per component of one destination pixel (SwsContext->dstBpc) is <= 10, data will be 15 bpc in 16 bits (int16_t) width. Else (i.e. SwsContext->dstBpc == 16), data will be 19bpc in 32 bits (int32_t) width.
dstW	width of destination image
src	pointer to source data to be scaled. If the number of bits per component of a source pixel (SwsContext->srcBpc) is 8, this is 8bpc in 8 bits (uint8_t) width. Else (i.e. SwsContext->dstBpc > 8), this is native depth in 16 bits (uint16_t) width. In other words, for 9-bit YUV input, this is 9bpc, for 10-bit YUV input, this is 10bpc, and for 16-bit RGB or YUV, this is 16bpc.
filter	filter coefficients to be used per output pixel for scaling. This contains 14bpp filtering coefficients. Guaranteed to contain dstW * filterSize entries.
filterPos	position of the first input pixel to be used for each output pixel during scaling. Guaranteed to contain dstW entries.
filterSize	the number of input coefficients to be used (and thus the number of input pixels to be used) for creating a single output pixel. Is aligned to 4 (and input coefficients thus padded with zeroes) to simplify creating SIMD code.

hyscale_fast

void(* SwsContext::hyscale_fast) (struct SwsContext *c, int16_t *dst, int dstWidth, const uint8_t *src, int srcW, int xInc)

Scale one horizontal line of input data using a bilinear filter to produce one line of output data.

Compared to SwsContext->hScale(), please take note of the following caveats when using these:

• Scaling is done using only 7 bits instead of 14-bit coefficients.
• You can use no more than 5 input pixels to produce 4 output pixels. Therefore, this filter should not be used for downscaling by more than ~20% in width (because that equals more than 5/4th downscaling and thus more than 5 pixels input per 4 pixels output).
• In general, bilinear filters create artifacts during downscaling (even when <20%), because one output pixel will span more than one input pixel, and thus some pixels will need edges of both neighbor pixels to interpolate the output pixel. Since you can use at most two input pixels per output pixel in bilinear scaling, this is impossible and thus downscaling by any size will create artifacts. To enable this type of scaling, set SWS_FLAG_FAST_BILINEAR in SwsContext->flags.

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The documentation for this struct was generated from the following file:

• libswscale/swscale_internal.h