[PD] Audio streaming for 3 or more channels?

[Bektur]

I’ve tried the multicast option with same setup, but unfortunately I’m getting the same issue (bad header tag error and distorted sound). 

Just out of curiosity I recorded the audio output I was getting

Best regards,
Bektur

On Jul 25, 2014, at 3:25 AM, Martin Peach <martin.peach at sympatico.ca> wrote:

> Looking through the source code of udpsend~ I don't think broadcast sends a different packet, I'll keep looking.
> Also note that multicast is supported. Have you tried that? It should be more efficient than broadcast.
> (udpsend-help has the messages used by [udpsend~] for multicast, udpsend~-help needs updating).
> 
> Martin
> 
> 
> On 2014-07-24 14:46, Bektur wrote:
>> Thanks for the advice!
>> 
>> I’m sorry for the late reply, but I finally got my hands on a windows machine, and here’s what I got:
>> 
>> - The issue with bad header tag in case of a broadcast is still there, so at least it’s not related to platform-specific implementation
>> - I managed to make it work by creating a set of separate [udpreceive~] objects for each client and they work almost without any noticeable problems with sound
>> 
>> I wish I could use wired connection, but since my clients are mobile devices, so I have to go with Wi-Fi.
>> 
>> Just in case if someone else would be looking for this problem, I think jack.udp is another possible option (since IIRC netjack and jackport don’t have mobile implementations). However, for now libpd + [udpreceive~]/[udpsend~] work well in local wireless networks.
>> 
>> Best regards,
>> Bektur
>> 
>> On Jul 21, 2014, at 11:06 PM, Martin Peach <martin.peach at sympatico.ca> wrote:
>> 
>>> On 2014-07-21 12:50, Bektur wrote:
>>>> 
>>>>> 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.
>>>> 
>>>> 
>>>> I haven’t found any workaround for this yet, but I’m planning to try reproducing these issues on a windows machine with ASIO drivers.
>>> 
>>> I suppose if you do it over a wired connection it will work better. Probably the WiFi is dropping packets and retransmitting, so things get out of sync. I don't know how broadcast UDP is implemented in WiFi, but I imagine it involves sending copies of the same packet to each receiver rather than a single packet addressed to multiple receivers.
>>> 
>>> Martin
>> 
>> 
>> 
> 

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