public static extern void av_bprint_channel_layout(AVBPrint* bp, int nb_channels, ulong channel_layout);
 public static extern int avio_read_to_bprint(AVIOContext* h, AVBPrint* pb, uint max_size);
 public static extern int avio_read_to_bprint(AVIOContext* @h, AVBPrint* @pb, ulong @max_size);