摘要：
tbn = the time base in AVStream that has come from the container tbc = the time base in AVCodecContext for the codec used for a particular stream tbr 阅读全文
摘要：
av_dup_packet函数 av_dup_packet会为destruct指针为av_destruct_packet_nofree的AVPacket新建一个缓冲区，将原有的缓冲区数据拷贝至新缓冲区，置data的值为新缓冲区的地址，同时设置destruct指针为av_destruct_packet 阅读全文