Re: [Csnd] Receiving array blob via OSC in Python

An osc blob is just a char buffer. It’s up to the receiver to convert it to usable data. The format is “documented” in the source code of OSCsend:

          ar = (ARRAYDAT *) p->arg[i];
          size = 0;
          for(j=0; j < ar->dimensions; j++) {
            size += (int32_t)ar->sizes[j]*sizeof(MYFLT);
          if(buffersize + size + 12 > bsize) {
            aux_realloc(csound, buffersize + size + 128, &p->aux);
            out = (char *) p->aux.auxp;
            bsize = p->aux.size;
          data = size + 8;
          byteswap((char *)&data,4);
          buffersize += 4;
          buffersize += 4;
          buffersize += ar->dimensions*4;
          buffersize += size;

From there, the format seems to be:

  • Total byte size of the data (int32)
  • dimensions (number of dimensions, int32)
  • sizes (array of int32 with size given by the dimensions)
  • the array data itself, as double (8 bytes per element)


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Thanks for this Eduardo. At the receiving end it looks like 96 chars, which seem to be the same no matter the number of dimensions and size of array I send.

Which is strange if the blob should be able to contain arrays of different sizes and dimensions.

I will ask the guy developing the library if he can explain it to me.

Best, Andreas