func: int av_read_packet(AVFormatContext *s,AVPacket *pkt) return ff_read_packet ( s , pkt ) ; int ff_read_packet(AVFormatContext *s,AVPacket *pkt) int ret ; int i ; AVStream * st ; AVPacketList * pktl = s -> raw_packet_buffer ; if ( pktl )  * pkt = pktl -> pkt; st = s -> streams [ pkt -> stream_index ]; if ( st -> request_probe <= 0 )  pkt -> data = ( ( void * ) 0 ); pkt -> size = 0; ret = ( ( s -> iformat -> read_packet ) ( s , pkt ) ); if ( ret < 0 )  if ( ! pktl || ret == - '\v' )  for (i = 0; i < s -> nb_streams; i++) st = s -> streams [ i ]; if ( st -> probe_packets )  probe_codec ( s , st , ( ( void * ) 0 ) ); if ( s -> flags & 0x0100 && pkt -> flags & 0x0002 )  if ( ( pkt -> stream_index ) >= ( ( unsigned int ) ( s -> nb_streams ) ) )  st = s -> streams [ pkt -> stream_index ]; pkt -> dts = wrap_timestamp ( st , pkt -> dts ); pkt -> pts = wrap_timestamp ( st , pkt -> pts ); if ( ! pktl && st -> request_probe <= 0 )  s -> raw_packet_buffer_remaining_size -= pkt -> size; static void probe_codec(AVFormatContext *s,AVStream *st,const AVPacket *pkt) if ( st -> request_probe > 0 )  AVProbeData * pd = & st -> probe_data ; if ( pkt )  uint8_t * new_buf = ( av_realloc ( ( pd -> buf ) , ( pd -> buf_size + pkt -> size + 32 ) ) ) ; if ( ! new_buf )  pd -> buf = new_buf; memcpy ( ( pd -> buf + pd -> buf_size ) , ( pkt -> data ) , ( pkt -> size ) ); pd -> buf_size += pkt -> size; memset ( ( pd -> buf + pd -> buf_size ) , 0 , 32 ); if ( end || ff_log2_c ( ( pd -> buf_size ) ) != ff_log2_c ( ( pd -> buf_size - pkt -> size ) ) )  int score = set_codec_from_probe_data ( s , st , pd ) ; if ( ( st -> codec -> codec_id ) != AV_CODEC_ID_NONE && score > 100 / 4 || end )  pd -> buf_size = 0; av_freep ( ( & pd -> buf ) ); 