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FFmpeg/libswscale/swscale.h
Ganesh Ajjanagadde cd8a0a9a9a swscale/swscale: add av_warn_unused_result to sws_init_context 
This should not trigger any warnings; but adds robustness.

Reviewed-by: Michael Niedermayer <michael@niedermayer.cc>
Signed-off-by: Ganesh Ajjanagadde <gajjanagadde@gmail.com>
2015-10-16 17:18:21 -04:00

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/*
* Copyright (C) 2001-2011 Michael Niedermayer <michaelni@gmx.at>
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#ifndef SWSCALE_SWSCALE_H
#define SWSCALE_SWSCALE_H
/**
* @file
* @ingroup libsws
* external API header
*/
#include <stdint.h>
#include "libavutil/avutil.h"
#include "libavutil/log.h"
#include "libavutil/pixfmt.h"
#include "version.h"
/**
* @defgroup libsws Color conversion and scaling
* @{
*
* Return the LIBSWSCALE_VERSION_INT constant.
*/
unsigned swscale_version(void);
/**
* Return the libswscale build-time configuration.
*/
const char *swscale_configuration(void);
/**
* Return the libswscale license.
*/
const char *swscale_license(void);
/* values for the flags, the stuff on the command line is different */
#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
//the following 3 flags are not completely implemented
//internal chrominace subsampling info
#define SWS_FULL_CHR_H_INT 0x2000
//input subsampling info
#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
/**
* Return a pointer to yuv<->rgb coefficients for the given colorspace
* suitable for sws_setColorspaceDetails().
*
* @param colorspace One of the SWS_CS_* macros. If invalid,
* SWS_CS_DEFAULT is used.
*/
const int *sws_getCoefficients(int colorspace);
// when used for filters they must have an odd number of elements
// coeffs cannot be shared between vectors
typedef struct SwsVector {
double *coeff; ///< pointer to the list of coefficients
int length; ///< number of coefficients in the vector
} SwsVector;
// vectors can be shared
typedef struct SwsFilter {
SwsVector *lumH;
SwsVector *lumV;
SwsVector *chrH;
SwsVector *chrV;
} SwsFilter;
struct SwsContext;
/**
* Return a positive value if pix_fmt is a supported input format, 0
* otherwise.
*/
int sws_isSupportedInput(enum AVPixelFormat pix_fmt);
/**
* Return a positive value if pix_fmt is a supported output format, 0
* otherwise.
*/
int sws_isSupportedOutput(enum AVPixelFormat pix_fmt);
/**
* @param[in] pix_fmt the pixel format
* @return a positive value if an endianness conversion for pix_fmt is
* supported, 0 otherwise.
*/
int sws_isSupportedEndiannessConversion(enum AVPixelFormat pix_fmt);
/**
* Allocate an empty SwsContext. This must be filled and passed to
* sws_init_context(). For filling see AVOptions, options.c and
* sws_setColorspaceDetails().
*/
struct SwsContext *sws_alloc_context(void);
/**
* Initialize the swscaler context sws_context.
*
* @return zero or positive value on success, a negative value on
* error
*/
av_warn_unused_result
int sws_init_context(struct SwsContext *sws_context, SwsFilter *srcFilter, SwsFilter *dstFilter);
/**
* Free the swscaler context swsContext.
* If swsContext is NULL, then does nothing.
*/
void sws_freeContext(struct SwsContext *swsContext);
/**
* Allocate and return an SwsContext. You need it to perform
* scaling/conversion operations using sws_scale().
*
* @param srcW the width of the source image
* @param srcH the height of the source image
* @param srcFormat the source image format
* @param dstW the width of the destination image
* @param dstH the height of the destination image
* @param dstFormat the destination image format
* @param flags specify which algorithm and options to use for rescaling
* @param 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
* @return 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
*/
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);
/**
* 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.
*
* @param c the scaling context previously created with
* sws_getContext()
* @param srcSlice the array containing the pointers to the planes of
* the source slice
* @param srcStride the array containing the strides for each plane of
* the source image
* @param 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
* @param srcSliceH the height of the source slice, that is the number
* of rows in the slice
* @param dst the array containing the pointers to the planes of
* the destination image
* @param dstStride the array containing the strides for each plane of
* the destination image
* @return the height of the output slice
*/
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[]);
/**
* @param dstRange flag indicating the while-black range of the output (1=jpeg / 0=mpeg)
* @param srcRange flag indicating the while-black range of the input (1=jpeg / 0=mpeg)
* @param table the yuv2rgb coefficients describing the output yuv space, normally ff_yuv2rgb_coeffs[x]
* @param inv_table the yuv2rgb coefficients describing the input yuv space, normally ff_yuv2rgb_coeffs[x]
* @param brightness 16.16 fixed point brightness correction
* @param contrast 16.16 fixed point contrast correction
* @param saturation 16.16 fixed point saturation correction
* @return -1 if not supported
*/
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);
/**
* @return -1 if not supported
*/
int sws_getColorspaceDetails(struct SwsContext *c, int **inv_table,
int *srcRange, int **table, int *dstRange,
int *brightness, int *contrast, int *saturation);
/**
* Allocate and return an uninitialized vector with length coefficients.
*/
SwsVector *sws_allocVec(int length);
/**
* Return a normalized Gaussian curve used to filter stuff
* quality = 3 is high quality, lower is lower quality.
*/
SwsVector *sws_getGaussianVec(double variance, double quality);
/**
* Allocate and return a vector with length coefficients, all
* with the same value c.
*/
SwsVector *sws_getConstVec(double c, int length);
/**
* Allocate and return a vector with just one coefficient, with
* value 1.0.
*/
SwsVector *sws_getIdentityVec(void);
/**
* Scale all the coefficients of a by the scalar value.
*/
void sws_scaleVec(SwsVector *a, double scalar);
/**
* Scale all the coefficients of a so that their sum equals height.
*/
void sws_normalizeVec(SwsVector *a, double height);
void sws_convVec(SwsVector *a, SwsVector *b);
void sws_addVec(SwsVector *a, SwsVector *b);
void sws_subVec(SwsVector *a, SwsVector *b);
void sws_shiftVec(SwsVector *a, int shift);
/**
* Allocate and return a clone of the vector a, that is a vector
* with the same coefficients as a.
*/
SwsVector *sws_cloneVec(SwsVector *a);
/**
* Print with av_log() a textual representation of the vector a
* if log_level <= av_log_level.
*/
void sws_printVec2(SwsVector *a, AVClass *log_ctx, int log_level);
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);
/**
* 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.
*/
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);
/**
* 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.
*
* @param src source frame buffer
* @param dst destination frame buffer
* @param num_pixels number of pixels to convert
* @param palette array with [256] entries, which must match color arrangement (RGB or BGR) of src
*/
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 24 bits.
*
* With the palette format "ABCD", the destination frame ends up with the format "ABC".
*
* @param src source frame buffer
* @param dst destination frame buffer
* @param num_pixels number of pixels to convert
* @param palette array with [256] entries, which must match color arrangement (RGB or BGR) of src
*/
void sws_convertPalette8ToPacked24(const uint8_t *src, uint8_t *dst, int num_pixels, const uint8_t *palette);
/**
* Get the AVClass for swsContext. It can be used in combination with
* AV_OPT_SEARCH_FAKE_OBJ for examining options.
*
* @see av_opt_find().
*/
const AVClass *sws_get_class(void);
/**
* @}
*/
#endif /* SWSCALE_SWSCALE_H */
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