VS2012 ffmpeg 没有定义的lrint

在common.h  

#ifndef AVUTIL_COMMON_H
#define AVUTIL_COMMON_H下添加

#define lrint(f) (f>=0?(int32_t)(f+(double)0.5):(int32_t)(f-(double)0.4))
#define lrintf(f) (f>=0?(int32_t)(f+(float)0.5):(int32_t)(f-(float)0.4))
#define llrintf(f) (f>=0?(int64_t)(f+(double)0.5):(int64_t)(f-(double)0.4))
#define llrint(f) (f>=0?(int64_t)(f+(float)0.5):(int64_t)(f-(float)0.4))