ffmpeg从内存读取文件

正常情况，ffmpeg直接从文件读取

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1 2	AVFormatContext * _ctx = NULL; avformat_open_input(&_ctx, _filePath, 0, 0);

 我们也可以自定义从内存读取，这样，可以用于读取一些加密的视频文件

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int fill_iobuffer(void * opaque,uint8_t *buf, int bufsize){          if(!feof(fp_open)){              int true_size=fread(buf,1,bufsize,fp_open);              return true_size;          }else{              return -1;          }      }       AVFormatContext * _ctx = NULL; unsigned char* _iobuffer = (unsigned char*)av_malloc(32768); AVIOContext* _avio = avio_alloc_context(_iobuffer , 32768 , 0 , NULL,fill_iobuffer,NULL,NULL); _ctx->pb = _avio;   fp_open=fopen(_filename,"rb+");    if ((ret = avformat_open_input(&_ctx, "nothing", 0, 0)) < 0) {     printf( "Could not open input file."); }