ffmpeg学习十三：图像数据格式的转换与图像的缩放

本文主要是介绍ffmpeg学习十三：图像数据格式的转换与图像的缩放，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

一.实现图像数据格式转换与图像缩放的三个重要函数

ffmpeg实现图像数据格式的转换以及图片的缩放的功能，主要使用swscale.h中的三个函数：
sws_getContext()
sws_scale()
sws_freeContext()
这三个函数的定义如下：
1.sws_getContext() :


/*** 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麓(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);