static int get_packetheader(NUTContext *nut, ByteIOContext *bc, int prefix_length, int calculate_checksum) { int64_t start, size, last_size; start= url_ftell(bc) - prefix_length; if(start != nut->packet_start + nut->written_packet_size){ av_log(nut->avf, AV_LOG_ERROR, "get_packetheader called at weird position\n"); return -1; } if(calculate_checksum) init_checksum(bc, update_adler32, 0); size= get_v(bc); last_size= get_v(bc); if(nut->written_packet_size != last_size){ av_log(nut->avf, AV_LOG_ERROR, "packet size missmatch %d != %lld at %lld\n", nut->written_packet_size, last_size, start); return -1; } nut->last_packet_start = nut->packet_start; nut->packet_start = start; nut->written_packet_size= size; return size; }