Message-Id: <4A619A8D-9BE8-4082-B28E-4F3EC19A6546@holtmann.org>
From: Marcel Holtmann <marcel@holtmann.org>
To: BlueZ development <bluez-devel@lists.sourceforge.net>
In-Reply-To: <loom.20080815T133352-774@post.gmane.org>
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Date: Fri, 15 Aug 2008 19:26:39 +0200
References: <loom.20080815T133352-774@post.gmane.org>
Subject: Re: [Bluez-devel] How to know the packet loss ratio of SCO socket
Reply-To: BlueZ development <bluez-devel@lists.sourceforge.net>
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Sender: bluez-devel-bounces@lists.sourceforge.net
Errors-To: bluez-devel-bounces@lists.sourceforge.net

Hi Jui-Hao,

> as the title said, I am writing a simple server-client socket  
> program for SCO
> connection. While client is sending the SCO packet to server, it  
> attaches a
> sequence number to it. Then I want server to estimate the packet loss.
> [Client program is as the following]
> for (i = 0; i < 48, i++) buf[i] = 0x7f;
> while (1) {
>  *(uint32_t *)buf = htobl(seq);
>  *(uint32_t *)(buf+4) = htobs(48);
>  if (send(sockfd, buf, 48, 0) < 0) break;
>  seq++;
>  usleep(1)
> }
>
> However, on the server side, the data is total different, and I am  
> not able to
> get the sequence number (the hcidump -x also shows different data  
> content as I
> expect. Also, it's weird that the content is repeated)
>
> Is this data encoded? or is there anyway to know the packet loss  
> ratio of the
> SCO connection?

SCO are voice connections and they are CVSD encoded. It is not a  
reliable data transport. Use L2CAP or RFCOMM for that.

Regards

Marcel


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