on linux x86 system, command line terminal,
music on,
“ffmpeg -f pulse -i xxxx(audio dev name,is a loudspeaker) /tmp/xxxx.wav” run perfect ,
“aplay -i /tmp/xxxx.wav” can play Captured speaker sound,

but,
in cpp code,

{
   ...
   AVInputFormat * fmt = av_find_input_format("pluse");
   if(!fmt)
      return -1;
   
   AVFormatContext *ctx = avformat_alloc_context();
   if(!ctx)
     return -1;

   int ret = avformat_open_input(&ctx,"xxxx dev name",fmt,NULL);  //block.......

   ...
}

why ternimal not,code blocking,Does anyone know?