[PD] udpreceive~/udpsend~ block size and broadcast streaming issues

PH via Pd-list pd-list at lists.iem.at
Thu Jun 19 02:50:14 CEST 2014

Hello everyone,

I had a question about udpreceive~ and udpsend~ objects from mrpeach externals. Here’s my problem:

I’m running a simple iOS application with libpd and udpreceive~ objects in the patch. The audio is sent from a computer with udpsend~ object, with only one channel currently being used. Whenever I stream to a single IP address everything works fine with almost unnoticeable latency. However, when I try to broadcast to multiple addresses in the network (as shown in udpsend~ help patch), I get two kinds of errors:

– On OS X, block size >= 512 triggers “Message too long (40)” error. It happens only on OS X (tried the same patch on ubuntu, and this error didn’t reappear), one of the possible solutions I found was to use smaller block size, but in such case it would cause the second kind of error

– On a client I get "udpreceive~: bad header tag (1)” error with incrementing numbers in the error. At first, I thought the libpd implementation was to blame, but it also happened when I run the same send and receive patches on two different computers running Pd-extended and connected over a local wireless network.

Is there any way to safely stream to multiple objects through one udpsend~ object? Also, what might be the source of bad header tag errors?

Best regards,

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