FFmpeg avio_alloc_context函数剖析

Posted 2020-10-19

函数原型
AVIOContext *avio_alloc_context(
                  unsigned char *buffer,
                  int buffer_size,
                  int write_flag,
                  void *opaque,
                  int (*read_packet)(void *opaque, uint8_t *buf, int buf_size),
                  int (*write_packet)(void *opaque, uint8_t *buf, int buf_size),
                  int64_t (*seek)(void *opaque, int64_t offset, int whence))
{
    //创建一个AVIOContext结构体
    AVIOContext *s = av_mallocz(sizeof(AVIOContext));
    if (!s)
        return NULL;
    //初始化AVIOContext结构体
    ffio_init_context(s, buffer, buffer_size, write_flag, opaque,
                  read_packet, write_packet, seek);
    return s;
}

#define BUF_SIZE    1024*16
AVIOContext* pAVIOContext = avio_alloc_context(pAVIOContext, BUF_SIZE, 0, this, ReadInputData, NULL, NULL);
ReadInputData函数将赋值给read_packet，当调用avcodec_send_packet函数，将会从ReadInputData读取指定的的BUF_SIZE
来进行分帧解析


疑问
设置FFmpeg读缓存区的大小，应该怎么设置比较合理